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0000-0001-7351-0827
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James Cook University
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Publisher: Springer Science and Business Media LLC
Date: 2018
Publisher: Medpharm Publications
Date: 24-02-2014
Abstract: Fowl adenovirus (FAdV) is a member of the genus Aviadenovirus and causes a number of economically important poultry diseases. One of these diseases, inclusion body hepatitis (IBH), has a worldwide distribution and is characterised by acute mortality (5% – 20%) in production chickens. The disease was first described in the United States of America in 1963 and has also been reported in Canada, the United Kingdom, Australia, France and Ireland, but until now, not in South Africa. Adenoviruses isolated from the first outbreak of IBH in South Africa were able to reproduce the disease in chicken embryo livers. The aim of the present study was to characterise the viruses and determine the pathogenicity of the FAdV strains responsible for the first reported case of IBH in South Africa. Polymerase chain reaction (PCR) lification of the L1 loop region of the fowl adenovirus hexon gene using degenerate primer pair hexon A/B was used to identify the viruses that were isolated. Restriction fragment length polymorphism (RFLP) of the lification products was used for the differentiation of 14 isolates of fowl adenovirus. Sequencing of the PCR products followed by amino acid comparison and phylogenetic analysis using the L1 loop region of the hexon protein was done to determine the identity of the isolates. Amino acid sequences of the hexon genes of all the South African isolates were compared with those of reference strains representing FAdV species. Amino acid comparison of 12 South Africa field isolates to FAdV reference strains revealed a high sequence identity ( 93.33%) with reference strains T8-A and 764. Two of the isolates had high sequence identity (93.40%) with reference strains P7-A, C2B and SR48. Phylogenetic analysis of the L1 loop region of the hexon protein of all 14 South African isolates was consistent with their RFLP clusters. The mortality rates of embryos challenged with 106 egg infective doses (EID50) FAdV 2 were 80% – 87% and mortality rates for embryos challenged with 105.95 (EID50) FAdV 8b were 65% – 80%.
Publisher: Springer Science and Business Media LLC
Date: 23-08-2014
DOI: 10.1007/S10493-013-9721-7
Abstract: Lumpy skin disease is a debilitating cattle disease caused by the lumpy skin disease virus (LSDV), belonging to the genus Capripoxvirus. Epidemics of the disease usually occur in summer, when insect activity is high. Limited information is available on how LSDV persists during inter-epidemic periods. Transmission of LSDV by mosquitoes such as Aedes aegypti has been shown to be mechanical, there is no carrier state in cattle and the role of wildlife in the epidemiology of the disease seems to be of minor importance. Recent studies in ticks have shown transstadial persistence of LSDV in Rhipicephalus appendiculatus and Amblyomma hebraeum as well as transovarial persistence of the virus in Rhipicephalus decoloratus, R. appendiculatus and A. hebraeum. The over-wintering of ticks off the host as part of their life cycles is well known: A. hebraeum and R. appendiculatus over-winter, for ex le, on the ground as engorged nymphs/unfed (emergent) adults while R. decoloratus over-winters on the ground as engorged females. In this study, transstadial and transovarial persistence of LSDV from experimentally infected A. hebraeum nymphs and R. decoloratus females after exposure to cold temperatures of 5 °C at night and 20 °C during the day for 2 months was reported. This observation suggests possible over-wintering of the virus in these tick species.
Publisher: MDPI AG
Date: 16-05-2019
DOI: 10.3390/V11050446
Abstract: The Palyam serogroup orbiviruses are associated with abortion and teratogenesis in cattle and other ruminants. Of the 13 different serotypes that have been identified, the full genome sequence of only one, Kasba, has been published. We undertook to perform Next Generation Sequencing (NGS) and phylogenetic analysis on 12 Palyam serotypes plus field isolates of the African serotypes in our possession. The Palyam serogroup was found to be most closely related to the African horse sickness virus group and showed the most distant evolutionary relationship to the equine encephalosis viruses (EEV). Amino acid sequence analysis revealed that the gene encoding VP7 was the most conserved within serotypes and VP2 and VP5 showed the highest degree of variation. A high degree of sequence identity was found for isolates from the same geographical region. The phylogenetic analysis revealed two clades where the African serotypes were all very closely related in one clade and the other clade contained the Australian and Asian serotypes and one African serotype, Petevo. It was evident from the sequence data that the geographical origin of Palyam serogroup viruses played an important role in the development of the different serotypes.
Publisher: American Society for Microbiology
Date: 27-08-2015
Abstract: This is a report of the complete genome sequences of plaque-selected isolates of each of the three virus strains included in a South African commercial trivalent African horse sickness attenuated live virus vaccine.
Publisher: Hindawi Limited
Date: 02-09-2020
DOI: 10.1111/TBED.13670
Publisher: Springer Science and Business Media LLC
Date: 28-12-2007
DOI: 10.1007/S00705-006-0893-X
Abstract: Foot-and-mouth disease serotype SAT-1 seems to be endemic in many sub-Saharan African countries. Phylogenetic analysis using the 1D gene of 51 SAT-1 isolates from East, West and southern Africa indicated the presence of at least 6 lineages and 11 genotypes with linkages between various geographical regions of the subcontinent. Differences were observed between countries in East Africa, the main focus of this study, with in idual countries suffering outbreaks from isolates belonging to various genotypes, which is evidence of reintroduction of strains and long-term circulation of outbreak viruses. The amount of variation observed has significant implications for disease control on the subcontinent.
Publisher: Elsevier BV
Date: 03-2007
DOI: 10.1016/J.VETPAR.2006.09.025
Abstract: Reverse line blot (RLB) is a hybridization assay that can be used to detect various blood parasites and differentiate between them. Results, using the RLB, showed that Babesia felis and Babesia leo occurred as single or mixed infections in various felid species, but most frequently in domestic cats and lions, respectively. Prevalence of infection in free-ranging cheetahs in Namibia was low (7, 5%), whereas 50% of free-ranging lions in South Africa and Swaziland were infected. A large number (52, 9%) of s les tested positive only for Babesia, neither B. felis nor B. leo. This could be an indication of at least one further, as yet undescribed, Babesia species in felids.
Publisher: Medpharm Publications
Date: 05-12-2018
Abstract: Bluetongue is primarily a disease of sheep in South Africa, while cattle and goats are mostly subclinically infected. The viraemia of bluetongue virus in cattle lasts much longer than in sheep and the role of cattle in the epidemiology of bluetongue in South Africa is poorly understood. Bluetongue virus has a segmented double-stranded ribonucleic acid genome and reassortment of genomes is a common feature. The aim of the study was to investigate whether reassortment occurs between vaccine and field strains when simultaneously administered to cattle. Six cattle between the ages of 6 and 12 months were infected with five strains of modified live vaccine bluetongue virus and a virulent field isolate of bluetongue virus 4. Blood s les were subsequently collected daily from these animals from day 1 to day 39 post-inoculation. Viruses were directly isolated during viraemia from the buffy coat on Vero cells using the plaque forming unit method. Analysis of plaques indicated that no reassortants between virulent field and vaccine strains occurred and the virulent bluetongue virus 4 was identified as the predominant virus strain. However, a reassortant virus between two bluetongue virus vaccine strains was isolated from the buffy coat. Whole genome sequences from the vaccine viruses were compared to the suspected reassortant and it was found that segment 8 exchanged between the bluetongue virus 8 and bluetongue virus 9 vaccine strains. The use of the live-attenuated bluetongue virus multivalent vaccine in South Africa causes circulation of different vaccine serotypes in Culicoides spp. and susceptible hosts and cattle might provide the ideal host for reassortment to occur.
Publisher: MDPI AG
Date: 21-01-2022
DOI: 10.3390/PATHOGENS11020125
Abstract: Rift Valley fever virus (RVFV) is a mosquito-borne, zoonotic phlebovirus-causing disease in domestic ruminants and humans in Africa, the Arabian Peninsula and some Indian Ocean islands. Outbreaks, characterized by abortion storms and a high morbidity rate in newborn animals, occur after heavy and prolonged rainfalls favouring the breeding of mosquitoes. However, the identity of the important mosquito vectors of RVFV is poorly known in most areas. Mosquitoes collected in the Ndumo area of tropical north-eastern KwaZulu-Natal (KZN), South Africa, were tested for RVFV nucleic acid using RT-PCR. The virus was detected in a single pool of unfed Aedes (Aedimorphus) durbanensis, indicating that this seasonally abundant mosquito species could serve as a vector in this area of endemic RVFV circulation. Phylogenetic analysis indicated the identified virus is closely related to two isolates from the earliest outbreaks, which occurred in central South Africa more than 60 years ago, indicating long-term endemicity in the region. Further research is required to understand the eco-epidemiology of RVFV and the vectors responsible for its circulation in the eastern tropical coastal region of southern Africa.
Publisher: AOSIS
Date: 24-02-2011
Abstract: Bluetongue (BT), a disease that affects mainly sheep, causes economic losses owing to not only its deleterious effects on animals but also its associated impact on the restriction of movement of livestock and livestock germplasm. The causative agent, bluetongue virus (BTV), can occur in the semen of rams and bulls at the time of peak viraemia and be transferred to a developing foetus. The risk of the transmission of BTV by bovine embryos is negligible if the embryos are washed according to the International Embryo Transfer Society (IETS) protocol. Two experiments were undertaken to determine whether this holds for ovine embryos that had been exposed to BTV. Firstly, the oestrus cycles of 12 ewes were synchronised and the 59 embryos that were obtained were exposed in vitro to BTV-2 and BTV-4 at a dilution of 1 x 102.88 and 1 x 103.5 respectively. In the second experiment, embryos were recovered from sheep at the peak of viraemia. A total of 96 embryos were collected from BTV-infected sheep 21 days after infection. In both experiments half the embryos were washed and treated with trypsin according to the IETS protocol while the remaining embryos were neither washed nor treated. All were tested for the presence of BTV using cell culture techniques. The virus was detected after three passages in BHK-21 cells only in one wash bath in the first experiment and two unwashed embryos exposed to BTV-4 at a titre of 1 x 103.5. No embryos or uterine flush fluids obtained from viraemic donors used in the second experiment were positive for BTV after the standard washing procedure had been followed. The washing procedure of the IETS protocol can thus clear sheep embryos infected with BTV either in vitro or in vivo.
Publisher: Medpharm Publications
Date: 05-12-2018
Abstract: Bluetongue is primarily a disease of sheep in South Africa, while cattle and goats are mostly subclinically infected. The viraemia of bluetongue virus in cattle lasts much longer than in sheep and the role of cattle in the epidemiology of bluetongue in South Africa is poorly understood. Bluetongue virus has a segmented double-stranded ribonucleic acid genome and reassortment of genomes is a common feature. The aim of the study was to investigate whether reassortment occurs between vaccine and field strains when simultaneously administered to cattle. Six cattle between the ages of 6 and 12 months were infected with five strains of modified live vaccine bluetongue virus and a virulent field isolate of bluetongue virus 4. Blood s les were subsequently collected daily from these animals from day 1 to day 39 post-inoculation. Viruses were directly isolated during viraemia from the buffy coat on Vero cells using the plaque forming unit method. Analysis of plaques indicated that no reassortants between virulent field and vaccine strains occurred and the virulent bluetongue virus 4 was identified as the predominant virus strain. However, a reassortant virus between two bluetongue virus vaccine strains was isolated from the buffy coat. Whole genome sequences from the vaccine viruses were compared to the suspected reassortant and it was found that segment 8 exchanged between the bluetongue virus 8 and bluetongue virus 9 vaccine strains. The use of the live-attenuated bluetongue virus multivalent vaccine in South Africa causes circulation of different vaccine serotypes in Culicoides spp. and susceptible hosts and cattle might provide the ideal host for reassortment to occur.
Publisher: American Society for Microbiology
Date: 28-05-2020
DOI: 10.1128/MRA.00310-20
Abstract: This is a report of the complete genome sequences of plaque-selected isolates of five virus strains included in bottle A of the South African Onderstepoort Biological Products commercial live attenuated bluetongue virus vaccine.
Publisher: American Society for Microbiology
Date: 08-2010
DOI: 10.1128/JCM.02266-09
Abstract: In a previous paper, we reported on a large number of cheetah blood specimens that gave positive signals only for Babesia and/or Theileria genus-specific probes on the reverse line blot (RLB) assay, indicating the presence of a novel species or variant of an existing species. Some of these specimens were investigated further by microscopic, serological, sequencing, and phylogenetic analyses. The near-full-length 18S rRNA genes of 13 s les, as well as the second internal transcribed spacer (ITS2) region, were lified, cloned, and sequenced. A species-specific RLB probe, designed to target the hypervariable V4 region of the 18S rRNA gene for detection of the novel Babesia sp., was used to screen an additional 137 cheetah blood specimens for the presence of the species. The prevalence of infection was 28.5%. Here we describe the morphology and phylogenetic relationships of the novel species, which we have named Babesia lengau sp. nov.
Publisher: Hindawi Limited
Date: 21-01-2020
DOI: 10.1111/TBED.13479
Abstract: Rift Valley fever (RVF) is a zoonotic viral disease of domestic ruminants in Africa and the Arabian Peninsula caused by a mosquito-borne Phlebovirus. Outbreaks in livestock and humans occur after heavy rains favour breeding of vectors, and the virus is thought to survive dry seasons in the eggs of floodwater-breeding aedine mosquitoes. We recently found high seroconversion rates to RVF virus (RVFV) in cattle and goats, in the absence of outbreaks, in far northern KwaZulu-Natal (KZN), South Africa. Here, we report the prevalence of, and factors associated with, neutralizing antibodies to RVFV in 326 sera collected opportunistically from nyala (Tragelaphus angasii) and impala (Aepyceros mel us) culled during 2016-2018 in two nature reserves in the same area. The overall seroprevalence of RVFV, determined using the serum neutralization test, was 35.0% (114/326 95%CI: 29.8%-40.4%) and tended to be higher in Ndumo Game Reserve (11/20 55.0% 95%CI: 31.5%-76.9%) than in Tembe Elephant Park (103/306 33.6% 95%CI: 28.4%-39.3%) (p = .087). The presence of antibodies in juveniles (6/21 28.6% 95%CI: 11.3%-52.2%) and sub-adults (13/65 20.0% 95%CI: 11.1%-37.8%) confirmed that infections had occurred at least until 2016, well after the 2008-2011 RVF outbreaks in South Africa. Odds of seropositivity was higher in adults than in sub-adults (OR = 3.98 95%CI: 1.83-8.67 p = .001), in males than in females (OR = 2.66 95%CI: 1.51-4.68 p = .001) and in animals collected ≤2 km from a sw or floodplain compared with those collected further away (OR = 3.30 95%CI: 1.70-6.38 p < .001). Under similar ecological conditions, domestic and wild ruminants may play a similar role in maintenance of RVFV circulation and either or both may serve as the mammalian host in a vector-host reservoir system. The study confirms the recent circulation of RVFV in the tropical coastal plain of northern KZN, providing the basis for investigation of factors affecting virus circulation and the role of wildlife in RVF epidemiology.
Publisher: Springer Science and Business Media LLC
Date: 13-09-2012
Publisher: Elsevier BV
Date: 1998
DOI: 10.1016/S0304-4017(97)00161-1
Abstract: Two eland Anaplasma isolates, AnapE1, from Kenya, and AnapE2, from South Africa were characterised. Their characterization was based on their pathogenicity to intact and splenectomized cattle and sheep and also their DNA profiles. Their DNA profiles were analysed and compared to Anaplasma marginale, A. ovis and A. centrale after endonuclease restrictions and probing with Anaplasma DNA probes, AC5-12 and AC-1. The results of the pathogenicity trials showed AnapE1 to be similar to A. ovis and AnapE2 an isolate of A. marginale. On DNA profiles, AnapE1 was close to A. ovis, with differences that occur even in same Anaplasma species isolates from different locations. On the other hand, AnapE2, resembled one of the A. marginale isolates known to occur in South Africa. The DNA profiles correlated well with the pathogenicity results. It is concluded that elands are carriers of both A. marginale and A. ovis parasites and are therefore important reservoirs that need attention in epidemiology of anaplasmosis.
Publisher: Elsevier BV
Date: 08-2013
DOI: 10.1016/J.VETMIC.2013.04.022
Abstract: Since the emergence of canine parvovirus type-2 (CPV-2) in the early 1970s, it has been evolving into novel genetic and antigenic variants (CPV-2a, 2b and 2c) that are unevenly distributed throughout the world. Genetic characterization of CPV-2 has not been documented in Africa since 1998 apart from the study carried out in Tunisia 2009. A total of 139 field s les were collected from South Africa and Nigeria, detected using PCR and the full length VP2-encoding gene of 27 positive s les were sequenced and genetically analyzed. Nigerian s les (n=6), South Africa (n=19) and vaccine strains (n=2) were compared with existing sequences obtained from GenBank. The results showed the presence of both CPV-2a and 2b in South Africa and only CPV-2a in Nigeria. No CPV-2c strain was detected during this study. Phylogenetic analysis showed a clustering not strictly associated with the geographical origin of the analyzed strains, although most of the South African strains tended to cluster together and the viral strains analyzed in this study were not completely distinct from CPV-2 strains from other parts of the world. Amino acid analysis showed predicted amino acid changes.
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.ANIREPROSCI.2018.04.080
Abstract: Lumpy skin disease is an economically important disease of cattle, caused by the lumpy skin disease virus (LSDV Capripoxvirus). It has a variable clinical appearance but, in severely affected animals, is associated with extensive skin damage, pneumonia and death. The LSDV can be found in the semen of infected bulls for prolonged periods of time, from where it can be transmitted by mating or artificial insemination and cause clinical disease in heifers and cows. In this study, an ejaculate was collected from a LSDV seronegative bull and confirmed free from LSDV DNA by PCR. The ejaculate was split into a control s le (C), a s le spiked with a 4 log TCID
Publisher: Microbiology Society
Date: 03-2017
DOI: 10.1099/JGV.0.000666
Abstract: Canine distemper virus (CDV) has emerged as a significant disease of wildlife, which is highly contagious and readily transmitted between susceptible hosts. Initially described as an infectious disease of domestic dogs, it is now recognized as a global multi-host pathogen, infecting and causing mass mortalities in a wide range of carnivore species. The last decade has seen the effect of numerous CDV outbreaks in various wildlife populations. Prevention of CDV requires a clear understanding of the potential hosts in danger of infection as well as the dynamic pathways CDV uses to gain entry to its host cells and its ability to initiate viral shedding and disease transmission. We review recent research conducted on CDV infections in wildlife, including the latest findings on the causes of host specificity and cellular receptors involved in distemper pathogenesis.
Publisher: Wiley
Date: 03-1993
DOI: 10.1111/J.1600-0714.1993.TB01039.X
Abstract: HPV type 18 DNA was identified in an intrabony ameloblastoma using radiolabelled in situ hybridization. The viral DNA was found in a verrucous lesion in a cystic area of the tumor. The absence of HPV DNA in other epithelial areas of the ameloblastoma is suggestive of a secondary infection. HPV is not considered to be an etiological factor in the pathogenesis of this ameloblastoma.
Publisher: Public Library of Science (PLoS)
Date: 03-05-2019
Publisher: Elsevier BV
Date: 05-1991
DOI: 10.1016/0166-0934(91)90048-5
Abstract: Different 32P-labelled genomic probes of bluetongue virus (BTV), epizootic haemorrhagic disease virus (EHDV) and equine encephalosis virus (EEV) were compared with respect to the detection of virus-specified RNA in infected cells. The probe derived from the genome segment that encodes nonstructural protein NS1 was found to be the most sensitive, detecting virus-specified RNA in glutaraldehyde-fixed cells as early as 2-3 h p.i. This comparison was based on the observation that the NS1 gene probe required a smaller number of infected cells to produce a positive hybridization signal than the other nucleic acid probes. The only exception was the EHDV NS2 gene probe which appeared to be as sensitive as the NS1 gene probe. The advantage of using the NS1 gene probe was particularly evident in the analysis of cells infected at very low multiplicities of infection. At a multiplicity of infection of 1 x 10(-5) plaque forming units/cell, virus-specified RNA could be detected 48 h after infection. The greater sensitivity of the NS1 gene-specific probe is ascribed to the fact that its target, the NS1 mRNA, is transcribed more frequently than the other target viral mRNAs. The major application of the cell-hybridization method is the rapid detection of small quantities of infectious virus particles.
Publisher: Cambridge University Press (CUP)
Date: 06-2004
DOI: 10.1017/S0950268803001833
Abstract: Thirty-one viruses causing SAT-2 outbreaks in seven West African countries between 1974 and 1991, and four viruses representative of East and Central Africa were genetically characterized in this study. Four major viral lineages (I-IV) were identified by phylogenetic analysis of an homologous 480 nucleotide region corresponding to the C-terminus end of VP1. Lineage I comprised two West African genotypes with viruses clustering according to year of isolation rather than geographical origin. Lineage II was represented by viruses isolated between 1979 and 1983 in two neighbouring West African countries, Senegal and The Gambia. Viruses from Nigeria and Eritrea, representative of West and East Africa respectively, constituted lineage III, whilst lineage IV, comprising viruses from Central and East Africa, was regionally and genetically distinct. This study revealed that unrestricted animal movement in West Africa is a major factor in disease dissemination and has also provided the first indication of trans-regional virus transmission.
Publisher: Medpharm Publications
Date: 24-02-2015
Abstract: In South Africa, outbreaks of African horse sickness (AHS) occur in summer no cases are reported in winter, from July to September. The AHS virus (AHSV) is transmitted almost exclusively by Culicoides midges (Diptera: Ceratopogonidae), of which Culicoides imicola is considered to be the most important vector. The over-wintering mechanism of AHSV is unknown. In this study, more than 500 000 Culicoides midges belonging to at least 26 species were collected in 88 light traps at weekly intervals between July 2010 and September 2011 near horses in the Onderstepoort area of South Africa. The dominant species was C. imicola. Despite relatively low temperatures and frost, at least 17 species, including C. imicola, were collected throughout winter (June–August). Although the mean number of midges per night fell from 50 000 (March) to 100 (July and August), no midge-free periods were found. This study, using virus isolation on cell cultures and a reverse transcriptase polymerase chain reaction (RT-PCR) assay, confirmed low infection prevalence in field midges and that the detection of virus correlated to high numbers. Although no virus was detected during this winter period, continuous adult activity indicated that transmission can potentially occur. The absence of AHSV in the midges during winter can be ascribed to the relatively low numbers collected coupled to low infection prevalence, low virus replication rates and low virus titres in the potentially infected midges. Cases of AHS in susceptible animals are likely to start as soon as Culicoides populations reach a critical level.
Publisher: Medpharm Publications
Date: 24-02-2014
Abstract: Inclusion body hepatitis is an acute disease of chickens ascribed to viruses of the genus Aviadenovirus and referred to as fowl adenovirus (FAdV). There are 12 FAdV types (FAdV1to FAdV8a and FAdV8b to FAdV11), classified into five species based on their genotype (designated FAdVA to FAdVE). A total of 218 000 chickens, 2–29 days of age, were affected over a 1-year period, all testing positive by microscopy, virus isolation and confirmation with polymerase chain reaction (PCR). Affected birds were depressed, lost body weight,were weak and had watery droppings. Pathological changes observed during necropsy indicated consistent changes in the liver, characterised by hepatomegaly, cholestasis and hepatitis. Lesions were also discernible in the spleen, kidney and gizzard wall and were characterised by splenomegaly, pinpoint haemorrhages, nephritis with haemorrhage,visceral gout and serosal ecchymosis of the gizzard wall. Histopathological lesions were most consistently observed in the liver but could also be seen in renal and splenic tissue. Virus isolation was achieved in embryonated eggs and most embryos revealed multifocalto diffuse hepatic necrosis, with a mixed cellular infiltrate of macrophages and heterophils(necro-granulomas), even in the absence of macroscopic pathology. Virus isolation results were verified by histopathology and PCR on embryonic material and further characterised by nucleotide sequence analysis. Two infectious bursal disease virus isolates were also made from the Klerksdorp flock. Nucleotide sequence analysis of the L1 hexon loop of all the FAdV isolates indicated homology (99%) with prototype strains P7-A for FAdV-2, as well as for FAdV-8b.
Publisher: Springer Science and Business Media LLC
Date: 03-2013
DOI: 10.1007/S10493-013-9679-5
Abstract: Lumpy skin disease is an economically important disease of cattle that is caused by the lumpy skin disease virus (LSDV), which belongs to the genus Capripoxvirus. It is endemic in Africa and outbreaks have also been reported in the Middle-East. Transmission has mostly been associated with blood-feeding insects but recently, the authors have demonstrated mechanical transmission by Rhipicephalus appendiculatus as well as mechanical/intrastadial and transstadial transmission by Amblyomma hebraeum. Saliva is the medium of transmission of pathogens transmitted by biting arthropods and, simultaneously, it potentiates infection in the vertebrate host. This study aimed to detect LSDV in saliva of A. hebraeum and R. appendiculatus adult ticks fed, as nymphs or as adults, on LSDV-infected animals, thereby also demonstrating transstadial or mechanical/intrastadial passage of the virus in these ticks. Saliva s les were tested for LSDV by real-time PCR and virus isolation. Supernatants obtained from virus isolation were further tested by real-time PCR to confirm that the cytopathic effects observed were due to LSDV. Lumpy skin disease virus was detected, for the first time, in saliva s les of both A. hebraeum and R. appendiculatus ticks. At the same time, mechanical/intrastadial and transstadial passage of the virus was demonstrated and confirmed in R. appendiculatus and A. hebraeum.
Publisher: MDPI AG
Date: 20-04-2021
DOI: 10.3390/V13040709
Abstract: Rift Valley fever phlebovirus (RVFV) infects humans and a wide range of ungulates and historically has caused devastating epidemics in Africa and the Arabian Peninsula. Lesions of naturally infected cases of Rift Valley fever (RVF) have only been described in detail in sheep with a few reports concerning cattle and humans. The most frequently observed lesion in both ruminants and humans is randomly distributed necrosis, particularly in the liver. Lesions supportive of vascular endothelial injury are also present and include mild hydropericardium, hydrothorax and ascites marked pulmonary congestion and oedema lymph node congestion and oedema and haemorrhages in many tissues. Although a complete understanding of RVF pathogenesis is still lacking, antigen-presenting cells in the skin are likely the early targets of the virus. Following suppression of type I IFN production and necrosis of dermal cells, RVFV spreads systemically, resulting in infection and necrosis of other cells in a variety of organs. Failure of both the innate and adaptive immune responses to control infection is exacerbated by apoptosis of lymphocytes. An excessive pro-inflammatory cytokine and chemokine response leads to microcirculatory dysfunction. Additionally, impairment of the coagulation system results in widespread haemorrhages. Fatal outcomes result from multiorgan failure, oedema in many organs (including the lungs and brain), hypotension, and circulatory shock. Here, we summarize current understanding of RVF cellular tropism as informed by lesions caused by natural infections. We specifically examine how extant knowledge informs current understanding regarding pathogenesis of the haemorrhagic fever form of RVF, identifying opportunities for future research.
Publisher: Wiley
Date: 04-2010
DOI: 10.1111/J.1439-0531.2008.01274.X
Abstract: The objectives of this work were to determine the site of persistence of lumpy skin disease virus (LSDV) in bulls shedding the virus in semen for a period longer than 28 days, to determine if the virus is present in all fractions of semen and to study lesions that developed in the genital tract. Six serologically negative postpubertal bulls were experimentally infected with a virulent field isolate of LSDV. The polymerase chain reaction (PCR) was performed on sheath washes, vesicular fluid, supernatant and cell-rich fractions of semen from day 10 to day 26 postinfection (p.i.). Bulls that were positive by PCR on the whole semen s le collected on day 28 p.i. were slaughtered and tissue s les from their genital tracts submitted for histopathological evaluation, immunoperoxidase staining, virus isolation and PCR. Two of the bulls developed severe lumpy skin disease (LSD) and were found to be shedding viral DNA in their semen on day 28 p.i. Viral DNA was identified in all semen fractions from all bulls, but mostly from the cell-rich fraction and from the severely affected bulls. The PCR assay was positive on postmortem s les of testes and epididymides from the two severely affected bulls. Virus could be recovered from the testes of these two bulls and from the epididymis of one of them. Immunoperoxidase staining was positive for LSDV staining in sections of testes and epididymides exhibiting necrosis. This study suggests that the testis and epididymis are sites of persistence of LSDV in bulls shedding virus in semen for prolonged periods and revealed that viral DNA is present in all fractions of the ejaculate.
Publisher: Hindawi Limited
Date: 24-05-2015
DOI: 10.1111/TBED.12102
Abstract: Lumpy skin disease (LSD) is an economically important disease caused by LSD virus (LSDV), a Capripoxvirus, characterized by fever and circumscribed skin lesions. It is suspected to be transmitted mechanically by biting flies. To assess the vector potential of Amblyomma hebraeum in transmission of LSDV, mechanical/intrastadial and transstadial modes of transmission of the virus by this tick species were investigated. Two cattle were artificially infected as sources (donors) of infection to ticks. Ticks were infected as either nymphs or adults. Male A. hebraeum ticks were partially fed on donor animals and transferred to recipient animals to test for mechanical/intrastadial transmission. Nymphal A. hebraeum were fed to repletion on donor animals. The emergent adult ticks were placed on recipient animals to test for transstadial transmission of the virus. Successful transmission of LSDV infection was determined in recipient animals by monitoring development of clinical signs, testing of blood for the presence of LSDV by real-time PCR, virus isolation and the serum neutralization test. This report provides further evidence of mechanical/intrastadial and, for the first time, transstadial transmission of LSDV by A. hebraeum. These findings implicate A. hebraeum as a possible maintenance host in the epidemiology of the disease.
Publisher: AOSIS
Date: 27-02-2015
Abstract: Rift Valley fever (RVF) is an arthropod-borne viral disease of importance in livestock and humans. Epidemics occur periodically in domestic ruminants. People in contact with infected livestock may develop disease that varies from mild flu-like symptoms to fatal viraemia. Livestock vaccination may assist in disease control. Rift Valley fever virus (RVFV) Clone 13 is a relatively new vaccine against RVF, derived from an avirulent natural mutant strain of RVFV, and has been shown to confer protective immunity against experimental infection with RVFV. The hypothesis tested in the current trial was that rams vaccinated with RVFV Clone 13 vaccine would not experience a reduction in semen quality (measured by evaluating the percentage progressively motile and percentage morphologically normal spermatozoa in successive ejaculates) relative to unvaccinated control animals. Ram lambs were screened for antibodies to RVFV using a serum neutralisation test. Animals without detectable antibodies (n = 23) were randomly allocated to either a test group (n = 12) or a control group (n = 11). Animals in the test group were vaccinated with RVFV Clone 13 vaccine. Daily rectal temperature measurements and weekly semen and blood s les were taken from all animals. Seven animals were eliminated from the statistical analysis because of potential confounding factors. Logistic regression analysis was performed on data gathered from the remaining animals to determine whether an association existed between animal group, rectal temperature and semen quality parameters. No correlation existed between the treatment group and values obtained for the semen quality parameters measured. There was no statistically significant post-vaccination decline in the percentage of live morphologically normal spermatozoa, or the percentage of progressively motile spermatozoa, either when assessed amongst all animals or when assessed within in idual groups. A repeat study with a larger s le size and a more comprehensive pre-screening process may be indicated to avoid the inclusion of unsuitable animals.
Publisher: Springer Berlin Heidelberg
Date: 1991
Publisher: Elsevier BV
Date: 03-2005
DOI: 10.1016/J.THERIOGENOLOGY.2004.06.013
Abstract: This work was done to establish the incidence and duration of excretion of lumpy skin disease virus (LSDV) in semen of experimentally infected susceptible bulls. Six serologically negative bulls 11-20 months of age were experimentally infected with a virulent field isolate (strain V248/93) of LSDV. Animals were observed for the development of clinical signs, blood was collected until day 90 after infection, and semen was collected every second day until day 18, then twice a week till day 63 and twice a month until three consecutive s les were negative when tested for LSDV by polymerase chain reaction (PCR). An aliquot of each s le which tested positive using PCR was inoculated onto cell monolayers for the recovery of virus. Two bulls developed severe lumpy skin disease (LSD), two bulls showed mild signs and two bulls showed a transient fever only. Multiple s les were positive on PCR from both of the severely affected bulls and one of the mildly affected bulls between days 10 and 159, days 8 and 132, and days 10 and 21 respectively. Only one s le from each of the other three bulls was positive on PCR. Virus was only isolated from two s les from one of the severely affected bulls and from five semen s les from the other. This study confirmed the excretion of LSDV in bovine semen for prolonged periods, even when obvious clinical signs of the disease were no longer apparent.
Publisher: Medpharm Publications
Date: 24-02-2014
Abstract: Rift Valley fever and lumpy skin disease are transboundary viral diseases endemic in Africa and some parts of the Middle East, but with increasing potential for global emergence. Wild ruminants, such as the African buffalo (Syncerus caffer), are thought to play a role in the epidemiology of these diseases. This study sought to expand the understanding of the role of buffalo in the maintenance of Rift Valley fever virus (RVFV) and lumpy skin disease virus (LSDV) by determining seroprevalence to these viruses during an inter-epidemic period. Buffaloes from the Kruger National Park (n = 138) and Hluhluwe-iMfolozi Park (n = 110) in South Africa were s led and tested for immunoglobulin G (IgG) and neutralising antibodies against LSDV and RVFV using an indirect enzyme-linked immunosorbent assay (I-ELISA) and the serum neutralisation test (SNT). The I-ELISA for LSDV and RVFV detected IgG antibodies in 70 of 248 (28.2%) and 15 of 248 (6.1%) buffaloes, respectively. Using the SNT, LSDV and RVFV neutralising antibodies were found in 5 of 66 (7.6%) and 12 of 57 (21.1%), respectively, of s les tested. The RVFV I-ELISA and SNT results correlated well with previously reported results. Of the 12 SNT RVFV-positive sera, three (25.0%) had very high SNT titres of 1:640. Neutralising antibody titres of more than 1:80 were found in 80.0% of the positive sera tested. The LSDV SNT results did not correlate with results obtained by the I-ELISA and neutralising antibody titres detected were low, with the highest (1:20) recorded in only two buffaloes, whilst 11 buffaloes (4.4%) had evidence of co-infection with both viruses. Results obtained in this study complement other reports suggesting a role for buffaloes in the epidemiology of these diseases during inter-epidemic periods.
Publisher: Elsevier BV
Date: 03-2014
Publisher: Springer Science and Business Media LLC
Date: 28-06-2019
DOI: 10.1007/S00705-019-04327-5
Abstract: Examination of lumpy skin disease virus (LSDV) isolates from different geographic regions and times revealed that assays developed in our laboratory for differentiating between virulent Israeli viruses and Neethling vaccine virus (NVV) are generally useful in most, if not all, endemic areas in which NVV-based vaccines are used. Recently it was revealed that the LSDV126 gene of field isolates contains a duplicated region of 27 bp (9 aa), while the vaccine viruses have only one copy. Phylogenetic analysis of a 532-bp segment carrying the LSDV126 gene and whole virus genome sequences revealed that LSDV isolates formed two groups: virulent and vaccine viruses. In this analysis, all of the capripox viruses that lack the ability to efficiently infect cattle were found to carry only one copy of the 27-bp fragment, suggesting that the LSDV126 gene plays an important role in the ability of capripox viruses to infect cattle. In silico analysis of potential antigenic sites in LSDV126 revealed that LSDV126 variants with only one copy of the repeat lack a potentially important antigenic epitope, supporting its possible significance in cattle infection. This study provides new information about the nature of the LSDV126 gene and its possible role in the life cycle of LSDV.
Publisher: AOSIS
Date: 24-02-2011
Abstract: Bovine tuberculosis (BTB), a chronic disease of mammals caused by Mycobacterium bovis, is a threat to South African wildlife. It has been reported that African buffaloes (Syncerus caffer) are reservoir hosts of BTB in South African wildlife populations. This study reports on the molecular identification and typing of 31 M. bovis isolates collected between 1993 and 2008, mainly from buffaloes but also from two lions and a bush pig, in the Hluhluwe-iMfolozi Park (HiP) in KwaZulu-Natal. To study the dynamics of BTB in the buffalo populations, 28 M. bovis isolates from the HiP and epidemiologically related parks were characterised using regions of difference deletion analysis for species identification and spoligotyping, variable number of tandem repeats (VNTR), polymorphic G–C-rich sequences and IS6110 restriction fragment length polymorphism (RFLP) genotyping methods. At least three distinct M. bovis genotypes were found amongst HiP s les. The combination of VNTR typing (using a 16-loci panel) and IS6110 RFLP revealed the presence of three additional genetic profiles in in idual buffaloes, demonstrating that the highest level of discrimination was achieved by these typing methods. One of the observed spoligotypes (SB0130) was dominant and represented 75% of isolates from buffaloes. A novel M. bovis spoligotype (SB1474), which is reported for the first time in this study, was observed in 14.3% of isolates from buffaloes. Based on the observed genetic relationships, the findings suggest independent introductions from at least three unrelated sources. These findings improve the knowledge regarding the ersity of circulating M. bovis strains in the HiP.
Publisher: No publisher found
Date: 2003
DOI: 10.1016/S0378-1135(02)00439-X
Abstract: The complete 1D genome region encoding the immunogenic and phylogenetically informative VP1 gene was genetically characterized for 23 South African Territories (SAT)-1 viruses causing foot-and-mouth (FMD) disease outbreaks in the West African region between 1975 and 1981. The results indicate that two independent outbreaks occurred, the first involved two West African countries, namely Niger and Nigeria, whilst the second affected Nigeria alone. In the former epizootic, virus circulation spanned a period of 2 years, whilst in the latter virus was recovered from the field over a 3 year period. Comparison of the West African viruses with SAT-1 viruses from other regions on the continent revealed that the two West African lineages identified in this study are regionally distinct. Furthermore, variation in VP1 gene length was identified in SAT-1 viruses for the first time, further emphasizing the uniqueness of these pathogens in West Africa. This first retrospective analysis in which the molecular epidemiology of SAT-1 viruses in West Africa is reported, provides a useful measure of the regional variation of these viruses and is an essential first step in the establishment of a West African sequence database that will be a useful reference for future outbreak eventualities.
Publisher: Springer Science and Business Media LLC
Date: 24-08-2014
DOI: 10.1007/S10493-013-9722-6
Abstract: Lumpy skin disease (LSD), an acute, sub-acute or inapparent disease of cattle, is caused by lumpy skin disease virus (LSDV), a member of the genus Capripoxvirus in the family Poxviridae. LSD is characterised by high fever, formation of circumscribed skin lesions and ulcerative lesions on the mucous membranes of the mouth, respiratory and digestive tracts. It is an economically important disease due to the permanent damage to hides, the reduction in productivity and trade restrictions imposed on affected areas. Transmission has been associated with blood-feeding insects such as stable flies (Stomoxysis calcitrans) and mosquitoes (Aedes aegypti). Mechanical (intrastadial) and transstadial transmission by Amblyomma hebraeum and Rhipicephalus appendiculatus as well as transovarial transmission by R. decoloratus have been reported. In this study transovarial passage of LSDV to larvae and subsequent transmission to recipient animals were demonstrated. The finding of transovarial passage of LSDV in female ticks shows the potential for A. hebraeum, R. appendiculatus and R. decoloratus to be reservoir hosts for LSDV.
Publisher: AOSIS
Date: 02-02-0025
Abstract: Newcastle disease (ND) is regarded as a highly contagious and economically important disease in poultry and has a worldwide distribution. Viral determinants for Newcastle disease virus (NDV) virulence are not completely understood and viruses of different pathotypes can be found at live-bird markets in different geographical areas. The prevalence of Newcastle disease in village poultry in Mozambique is not well documented and strains of NDV involved in yearly outbreaks are unknown. The fusion (F) protein is an important determinant of pathogenicity of the virus and is used commonly for phylogenetic analysis. Newcastle disease viruses from various geographical regions of Mozambique were sequenced and compared genetically to published sequences obtained from GenBank. S les were collected in three different areas of Mozambique and NDV was isolated by infection of embryonated chicken eggs. Sequence analysis of the F-protein encoding gene was used to classify 28 isolates from Mozambique into genotypes and compare these genotypes phylogenetically with existing genotypes found in GenBank. The isolates obtained from Mozambique grouped mainly into two clades. In the first clade, 12 isolates grouped together with sequences of isolates representing genotypes from Mozambique that were previously described. In the second clade, 16 isolates group together with sequences obtained from GenBank originating from Australia, China, South Africa and the USA. Eleven of these isolates showed a high similarity with sequences from South Africa. The number of s les sequenced (n = 28), as well as the relatively small geographical collection area used in this study, are too small to be a representation of the circulating viruses in Mozambique in 2005. Viruses characterised in this study belonged to lineage 5b, a similar finding of a previous study 10 years ago. From this data, it merely can be concluded that no new introduction of the virus occurred from 1995 to 2005 in Mozambique.
Publisher: SAGE Publications
Date: 26-06-2020
Abstract: Bluetongue is a serious non-contagious vector-borne viral disease in ruminants, causing poor animal welfare and economic consequences globally. Concern has been raised about the development of novel bluetongue virus (BTV) strains and their possibly altered virulence through the process of viral reassortment. Virulence is traditionally estimated in lethal dose 50 (LD 50 ) studies in murine models, but agreement with both in vitro and virulence in ruminants is questionable, and a refined experimental design is needed. Specific reassortants between wild-type and vaccine strains of BTV-1, -6 and -8 have previously been developed by reverse genetics. The aim of the present study was to rank the in vivo virulence of these parental and reassortant BTV strains by calculating LD 50 in a murine model by using an experimental design that is new to virology: a between-patient optimised three-level response surface pathway design. The inoculation procedure was intracranial. Fifteen suckling mice were used to establish LD 50 for each strain. Three parental and five reassortant virus strains were included. The LD 50 s varied from of 0.1 (95% confidence interval (CI) 0–0.20) to 3.3 (95% CI 2.96–3.72) tissue culture infectious dose 50/ml. The results support the hypothesis that reassortment in BTV may lead to increased virulence in mice with potential negative consequences for the natural ruminant host. The ranking showed low agreement with in vitro properties and virulence in ruminants according to existing literature. Refined design such as response surface pathway design was found suitable for use in virology, and it introduces significant ethical and scientific improvements.
Publisher: Elsevier BV
Date: 06-2009
DOI: 10.1016/J.JVIROMET.2009.02.008
Abstract: The endangered Cape mountain zebra (Equus zebra zebra) is protected in small numbers in a few isolated populations in South African game parks. Since 1995, sarcoid lesions appeared in zebras in two of the parks. This study was undertaken to investigate if bovine papillomavirus (BPV) is associated with sarcoids in these zebras. A conventional PCR, targeting the E5 ORF of BPV, and subsequent RFLP analysis were initially used to demonstrate the presence of BPV-1 and -2 DNAs in zebra sarcoid tumours. A rapid, sensitive and reliable real-time PCR to detect and distinguish between BPV-1 and -2 infections in zebras was developed. With this assay it was demonstrated that BPV-1 and -2 DNA (either single or mixed infections) are present in sarcoid tumour, healthy skin and blood of sarcoid-affected and healthy zebras from sarcoid-affected parks as well as in the blood of zebras from parks where no sarcoid has been observed before.
Publisher: Elsevier BV
Date: 06-2014
DOI: 10.1016/J.VETMIC.2014.03.006
Abstract: Bluetongue virus (BTV), a segmented dsRNA virus, is the causative agent of bluetongue (BT), an economically important viral haemorrhagic disease of ruminants. Bluetongue virus can exchange its genome segments in mammalian or insect cells that have been co-infected with more than one strain of the virus. This process, may potentially give rise to the generation of novel reassortant strains that may differ from parental strains in regards to their phenotypic characteristics. To investigate the potential effects of reassortment on the virus' phenotype, parental as well as reassortant strains of BTV serotype 1, 6, 8, that were derived from attenuated and wild type strains by reverse genetics, were studied in vitro for their virus replication kinetics and cytopathogenicity in mammalian (Vero) cell cultures. The results indicate that genetic reassortment can affect viral replication kinetics, the cytopathogenicity and extent/mechanism of cell death in infected cell cultures. In particular, some reassortants of non-virulent vaccine (BTV-1 and BTV-6) and virulent field origin (BTV-8) demonstrate more pronounced cytopathic effects compared to their parental strains. Some reassortant strains in addition replicated to high titres in vitro despite being composed of genome segments from slow and fast replicating parental strains. The latter result may have implications for the level of viraemia in the mammalian host and subsequent uptake and transmission of reassortant strains (and their genome segments) by Culicoides vectors. Increased rates of CPE induction could further suggest a higher virulence for reassortant strains in vivo. Overall, these findings raise questions in regards to the use of modified-live virus (MLV) vaccines and risk of reassortment in the field. To further address these questions, additional experimental infection studies using insects and/or animal models should be conducted, to determine whether these results have significant implications in vivo.
Publisher: American Society for Microbiology
Date: 31-12-2015
Abstract: This is a report of the complete genome sequences of plaque-selected isolates of each of the four virus strains included in a South African commercial tetravalent African horse sickness attenuated live virus vaccine.
Publisher: Hindawi Limited
Date: 07-04-2019
DOI: 10.1111/TBED.13179
Abstract: Lumpy skin disease (LSD) is an important transboundary animal disease of cattle with significant economic impact because of the implications for international trade in live animals and animal products. LSD is caused by a Capripoxvirus, LSD virus (LSDV), and results in extensive hide and udder damage, fever and pneumonia. LSDV can be shed in semen of infected bulls for prolonged periods and transmitted venereally to cows at high doses. This study examined the effects of LSDV in frozen-thawed semen on in vitro embryo production parameters, including viral status of media and resulting embryos. Bovine oocytes were harvested from abattoir-collected ovaries and split into three experimental groups. After maturation, the oocytes were fertilized in vitro with frozen-thawed semen spiked with a high (HD) or a lower (LD) dose of LSDV, or with LSDV-free semen (control). Following day 7 and day 8 blastocyst evaluation, PCR and virus isolation were performed on all embryonic structures. After completing sufficient replicates to reach 1,000 inseminated oocytes, further in vitro fertilization (IVF) runs were performed to provide material for electron microscopy (EM) and embryo washing procedures. Overall, in vitro embryo yield was significantly reduced by the presence of LSDV in frozen-thawed semen, irrespective of viral dose. When semen with a lower viral dose was used, significantly lower oocyte cleavage rates were observed. LSDV could be detected in fertilization media and all embryo structures, when higher doses of LSDV were present in the frozen-thawed semen used for IVF. Electron microscopy demonstrated LSDV virions inside blastocysts. Following the International Embryo Transfer Society washing procedure resulted in embryos free of viral DNA however, this may be attributable to a s ling dilution effect and should be interpreted with caution. Further research is required to better quantify the risk of LSDV transmission via assisted reproductive procedures.
Publisher: Springer Science and Business Media LLC
Date: 2001
Abstract: Genetic relationships of serotype O foot-and-mouth disease (FMD) viruses recovered from outbreaks of the disease in the West African countries of Niger, Burkina Faso and, Ghana (1988-1993) and those from South Africa (2000) were determined by partial VP1 gene characterization. A 581-bp fragment, corresponding to the C-terminus half of the ID (VP1 gene) region was lified and sequenced. An homologous region of 495 nucleotides was ultimately used to determine genetic relationships of serotype O viruses from the Middle East, Europe, South America, North Africa, East Africa, southern Africa and Asia. Seven distinct type O genotypes were identified by phylogenetic reconstruction, consisting of viruses from the following geographical regions: Genotype A: Asia, the Middle East, and South Africa, Genotype B: East Africa, Genotype C: West and North Africa, Genotype D: Taiwan and Russia, Genotype E: Angola and Venezuela, Genotype F: Western Europe, and Genotype G: Europe and South America. The genotypes constitute three different evolutionary lineages (I-III), which correspond to three discrete continental regions, some of which display inter-continental distributions due to introductions. Results further indicate that the outbreaks in Burkina Faso (1992) and Ghana (1993) are part of the same epizootic and that the strain involved in a recent outbreak of the disease in South Africa is most closely related (97% sequence identity) to a 1997 Bangladesh strain.
Publisher: Springer Science and Business Media LLC
Date: 18-01-2016
DOI: 10.1007/S00705-015-2741-3
Abstract: Phylogenetic networks and sequence analysis allow a more accurate understanding of the serotypes, genetic relationships and epidemiology of viruses. Based on gene sequences of the conserved segment 10 (NS3), bluetongue virus (BTV) can be ided into five topotypes. In this molecular epidemiology study, segment 10 sequence data of 11 isolates obtained from the Virology Section of the Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, were analyzed and compared to sequence data of worldwide BTV strains available in the GenBank database. The consensus nucleotide sequences of NS3/A showed intermediate levels of variation, with the nucleotide sequence identity ranging from 79.72 % to 100 %. All 11 strains demonstrated conserved amino acid characteristics. Phylogenetic networks were used to identify BTV topotypes. The phylogeny obtained from the nucleotide sequence data of the NS3/A-encoding gene presented three major and two minor topotypes. The clustering of strains from different geographical areas into the same group indicated spatial spread of the segment 10 genes, either through gene reassortment or through the introduction of new strains from other geographical areas via trade. The effect of reassortment and genetic drift on BTV and the importance of correct serotyping to identify viral strains are highlighted.
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.VETMIC.2010.02.036
Abstract: Electrophoretic techniques that can be used for genotyping of bacterial pathogens ranges from manual, low-cost, agarose gels to high-throughput capillary electrophoresis sequencing machines. These two methods are currently employed in the electrophoresis of PCR products used in multiple locus VNTR (variable number of tandem repeats) analysis (MLVA), i.e. the agarose electrophoresis (AE) and the capillary electrophoresis (CE). Some authors have suggested that clusters generated by AE are less reliable than those generated by CE and that the latter is a more sensitive technique than the former when typing Mycobacterium tuberculosis complex (MTC) isolates. Because such a claim could have significant consequences for investigators in this field, a comparison was made on 19 Belgian Mycobacterium bovis strains which had previously been genotyped using CE VNTR analysis. The VNTR profiles of the CE VNTR analysis were compared with those obtained by AE VNTR analysis at 14 VNTR loci. Our results indicated that there were no differences in copy numbers at all loci tested when the copy numbers obtained by the AE VNTR analysis were compared with those obtained by CE VNTR analysis. The use of AE VNTR analysis in mycobacterial genotyping does not alter the sensitivity of the MLVA technique compared with the CE VNTR analysis. The AE VNTR can therefore be regarded as a viable alternative in moderately equipped laboratories that cannot afford the expensive equipment required for CE VNTR analysis and data obtained by AE VNTR analysis can be shared between laboratories which use the CE VNTR method.
Publisher: Elsevier BV
Date: 04-2014
DOI: 10.1016/J.JVIROMET.2013.12.023
Abstract: A major problem with the testing of virucidal efficacy using current protocols is that scoring of virus-induced cytopathic effect (CPE) is dependent on subjective visual interpretation using light microscopy. The current report details the use of an electrical impedance assay (xCELLigence, ACEA Biosciences) for its utility in virucidal efficacy testing. In this study, the xCELLigence system was used in a procedure developed from guidelines given by the Deutsche Vereiniging zur Bekämpfung der Viruskrankheiten (DVV) (German Association for the Control of Virus Diseases) in order to demonstrate the inactivation of infectious bursal disease virus using a commercial virucide. Although the modified DVV assay using the xCELLigence system yielded identical results (i.e. a 5-log10 reduction in viral infectivity) as the traditional DVV assay, the system allows virucidal efficacy and cytotoxicity to be measured in a more precise and reproducible fashion.
Publisher: Elsevier BV
Date: 07-2011
DOI: 10.1016/J.VETMIC.2011.02.037
Abstract: From 2005 to 2007, Mycobacterium tuberculosis complex (MTC) strains were isolated from cattle, goats and pigs s les collected at the Bodija abattoir and from human s les from tuberculosis patients and livestock traders at the Akinyele cattle market in Ibadan, Southwestern Nigeria. Seventy four isolates obtained from humans (24) and livestock (50) were identified as MTC strains. Thirty two isolates were spoligotyped. Nineteen of these 32 isolates were identified as M. tuberculosis whilst 13 were identified as Mycobacterium bovis. M. bovis was isolated from two humans, whereas M. tuberculosis was isolated from a bovine, a pig and a goat. All the M. bovis isolates identified in this study belonged to the Africa 1 clonal complex. Multiple locus VNTR [variable number of tandem repeats] analysis (MLVA) was carried out on the 74 isolates. Three major clusters were defined. Group A consisted of 24 M. tuberculosis isolates (MLVA genotypes 1-18). One strain was isolated from a bovine and one from a pig. Group B consisted of 49 M. bovis strains (MLVA genotypes 19-48), mainly of cattle origin but also included four goat, nine pig and two human isolates. Group C consisted of a single M. tuberculosis isolate (MLVA genotype 49) obtained from a goat. Spoligotyping and MLVA confirmed it as clustering with the East Africa Indian clade found in humans in Sudan and the Republic of Djibouti. The isolation of three M. tuberculosis strains from livestock raises the question of their epidemiological importance as a source of infection for humans.
Publisher: MDPI AG
Date: 23-07-2023
DOI: 10.3390/V15071611
Abstract: Bluetongue (BT), a viral disease of ruminants, is endemic throughout South Africa, where outbreaks of different serotypes occur. The predominant serotypes can differ annually due to herd immunity provided by annual vaccinations using a live attenuated vaccine (LAV). This has led to both wild-type and vaccine strains co-circulating in the field, potentially leading to novel viral strains due to reassortment and recombination. Little is known about the molecular evolution of the virus in the field in South Africa. The purpose of this study was to investigate the genetic ersity of field strains of BTV in South Africa and to provide an initial assessment of the evolutionary processes shaping BTV genetic ersity in the field. Complete genomes of 35 field viruses belonging to 11 serotypes, collected from different regions of the country between 2011 and 2017, were sequenced. The sequences were phylogenetically analysed in relation to all the BTV sequences available from GenBank, including the LAVs and reference strains, resulting in the analyses and reassortment detection of 305 BTVs. Phylogenomic analysis indicated a geographical selection of the genome segments, irrespective of the serotype. Based on the initial assessment of the current genomic clades that circulate in South Africa, the selection for specific clades is prevalent in directing genome segment reassortment, which seems to exclude the vaccine strains and in multiple cases involves Segment-2 resulting in antigenic shift.
Publisher: Medpharm Publications
Date: 24-02-2014
Abstract: Bluetongue (BT) is a non-contagious disease of sheep and other domestic and wild ruminants caused by the bluetongue virus (BTV). Currently 26 serotypes of the virus have been identified. In South Africa, 22 serotypes have been identified and BT is controlled mainly by annual vaccinations using a freeze-dried live attenuated polyvalent BTV vaccine. The vaccine is constituted of 15 BTV serotypes ided into three separate bottles and the aim is to develop a vaccine using fewer serotypes without compromising the immunity against the disease. This study is based on previously reported cross-neutralisation of specific BTV serotypes in in vitro studies. Bluetongue virus serotype 4 was selected for this trial and was tested for cross-protection against serotype 4 (control), 1 (unrelated serotype), 9, 10 and 11 in sheep using the serum neutralisation test. The purpose of the study was to determine possible cross-protection of different serotypes in sheep. Of those vaccinated with BTV-4 and challenged with BTV-1, which is not directly related to BTV-4, 20% were completely protected and 80% showed clinical signs, but the reaction was not as severe as amongst the unvaccinated animals. In the group challenged with BTV-10, some showed good protection and some became very sick. Those challenged with BTV-9 and BTV-11 had good protection. The results showed that BTV-4 does not only elicit a specific immune response but can also protect against other serotypes.
Publisher: American Society for Microbiology
Date: 13-07-2018
Abstract: Canine distemper virus causes global multihost infectious disease. This report details complete genome sequences of three vaccine and two new wild-type strains. The wild-type strains belong to the South African lineage, and all three vaccine strains to the America 1 lineage. This constitutes the first genomic sequences of this virus from South Africa.
Publisher: Elsevier BV
Date: 03-2001
Publisher: Elsevier BV
Date: 2022
DOI: 10.1016/J.TVJL.2021.105785
Abstract: In recent years, lumpy skin disease virus has extended its geographical range outside of endemic sub-Saharan countries to the Middle East and Asia indicating transboundary spread. Recently, lumpy skin disease (LSD) outbreaks have been reported in Asian countries such as Bangladesh, India, China, Nepal, Bhutan, Vietnam, Myanmar, Sri Lanka, Thailand, Malaysia, Laos and for the first time and represent a cause of serious concern for their livestock and dairy industries. This report summarizes information on the recent outbreaks of LSD in southern Asia and emphasizes the threat it poses to neighbouring countries. Various strategies and actions needed to control outbreaks of this emerging disease in Asia are also suggested.
Publisher: Elsevier BV
Date: 03-2007
DOI: 10.1016/J.VACCINE.2006.12.010
Abstract: Twelve serologically negative bulls were used, six were vaccinated with a modified live LSD vaccine and six unvaccinated. All were then experimentally infected with a virulent field strain of LSDV. No clinical abnormality was detected following vaccination, and mild clinical signs were seen in four vaccinated bulls following challenge. Virus was not found in semen of vaccinated bulls. Two of the unvaccinated bulls developed severe LSD and four showed mild symptoms, all excreted the virus in the semen following challenge. This study confirmed the ability of LSD vaccination to prevent the excretion of LSDV in semen of vaccinated bulls.
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.JVIROMET.2017.01.014
Abstract: Rift Valley fever (RVF), caused by an arthropod borne Phlebovirus in the family Bunyaviridae, is a haemorrhagic disease that affects ruminants and humans. Due to the zoonotic nature of the virus, a biosafety level 3 laboratory is required for isolation of the virus. Fresh and frozen s les are the preferred s le type for isolation and acquisition of sequence data. However, these s les are scarce in addition to posing a health risk to laboratory personnel. Archived formalin-fixed, paraffin-embedded (FFPE) tissue s les are safe and readily available, however FFPE derived RNA is in most cases degraded and cross-linked in peptide bonds and it is unknown whether the s le type would be suitable as reference material for retrospective phylogenetic studies. A RT-PCR assay targeting a 490 nt portion of the structural G
Publisher: Elsevier BV
Date: 06-2015
DOI: 10.3382/PS/PEV084
Abstract: Ostrich (Struthio camelus) chicks less than 3 mo age are observed to experience a high mortality rate that is often associated with enteritis. This study was undertaken to investigate the infectious bacteria implicated in ostrich chick enteritis. Postmortems were performed on 122 ostrich chicks aged from 1 d to 3 mo and intestinal s les were subjected to bacterial culture. Bacterial isolates were typed by PCR and serotyping. Escherichia coli (E. coli 49%) was the most frequently isolated from the s les followed by Clostridium perfringens (C. perfringens 20%), Enterococcus spp. (16%), and Salmonella spp. (7%). Of the E. coli, 39% were categorized as enteropathogenic E. coli, 4% enterotoxigenic E. coli, and no enterohaemorrhagic E. coli were found. The majority (93%) of C. perfringens was Type A and only 7% was Type E. C. perfringens Types B through D were not present. The netB gene that encodes NetB toxin was identified from 16% of the C. perfringens isolated. All the C. perfringens Type E harbored the netB gene and just 10% of the C. perfringens Type A had this gene. Three Salmonella serotypes were identified: Salmonella Muenchen (S. Muenchen 80%), S. Hayindongo (13%), and S. Othmarschen (7%). The indication is that the cause of enteritis in ostrich chicks is bacterial-involving: enteropathogenic E. coli and enterotoxigenic E. coli C. perfringens Types A and E (with the possible influence of netB gene) and S. Muenchen, S. Hayindongo, and S. Othmarschen.
Publisher: Elsevier BV
Date: 03-2015
Publisher: Springer Science and Business Media LLC
Date: 05-2013
Abstract: Although reported sporadically from various countries, feline babesiosis appears to be a significant clinical entity only in South Africa, where Babesia felis is usually incriminated as the causative agent. Babesia lengau , recently described from asymptomatic cheetahs, has now possibly been incriminated as the causative agent in two severe clinical cases in domestic cats. Both cats were euthanised in extremis . While typical feline babesiosis in South Africa is an afebrile disease with a chronic manifestation, there was acute onset of severe clinical signs in both cats and their body temperatures were above the normal range when they were presented for treatment. Haemolytic anaemia was confirmed in one case. To our knowledge, this is the first report of cerebral babesiosis in cats. On reverse line blot 18S rDNA PCR products obtained from both cats showed positive hybridization profiles with the B. lengau species-specific probe. The two partial parasite 18S rRNA gene sequences obtained, showed high sequence similarity (99.9%) to B. lengau . In a representative tree constructed by the neighbor-joining method using the two-parameter model of Kimura the two obtained partial 18S rDNA sequences and that of B. lengau formed a monophyletic group with B. conradae and sequences previously isolated from humans and wildlife in the western USA. All clinical cases of feline babesiosis in South Africa are not necessarily caused by B. felis . Other piroplasms, e.g. B. lengau , may be incriminated in clinical cases, especially those occurring outside the known endemic area.
Publisher: Wiley
Date: 11-1999
DOI: 10.1046/J.1365-2915.1999.00188.X
Abstract: Equine encephalosis virus (EEV) was recognized and described in the Republic of South Africa in 1967 and subsequent serological studies have shown this orbivirus to be both widespread and prevalent in southern Africa. In the present study it was shown that wild-caught Culicoides (Avaritia) imicola Kieffer (Diptera: Ceratopogonidae) can become infected with and permit the replication of the Bryanston serotype of EEV following membrane-feeding on infective blood containing 5.0 log10 plaque-forming-units (PFU)/ml. The mean prevalence of Bryanston virus infection in C. imicola after 10 days extrinsic incubation at 23.5 degrees C was 22.3% (23/103). The mean infectivity of Bryanston virus in the infected C. imicola increased from 1.3 log10 PFU/midge, in insects assayed immediately after feeding on the blood-virus mixture, to 2.6 log10 PFU/midge in insects assayed after incubation. The virus concentration in in idual C. imicola infected with the Bryanston serotype of EEV ranged from 0.7 to 3.6 log10 PFU/midge. Bryanston virus titres higher than 2.5 log10 TCID50, found in in idual C. imicola, suggest that this species may be able to transmit this virus to susceptible hosts. Prevalence of virus infection in C. imicola was determined by PFU and microtitration assays on both BHK and Vero cells and confirmation of the Bryanston serotype of EEV was determined by plaque inhibition. No virus replication could be demonstrated in 102 C. nivosus tested after the incubation period, suggesting that not all Culicoides species are equally susceptible to Bryanston virus infection. Other Culicoides species that survived the incubation period and that were negative for the presence of Bryanston virus were C. pycnostictus (42), C. leucostictus (7), C. magnus (2), C. bolitinos (1) and C. bedfordi (1).
Publisher: Hindawi Limited
Date: 13-11-2017
DOI: 10.1111/TBED.12444
Publisher: SAGE Publications
Date: 05-2008
DOI: 10.1354/VP.45-3-310
Abstract: Sheep inoculated with a virulent South African strain of bluetongue (BT) virus serotype 4 developed severe clinical signs and lesions characteristic of fulminant BT, including coronitis, hemorrhage and ulceration of the mucosal lining of the oral cavity and forestomaches, hemorrhage in the wall of the pulmonary artery, and focally extensive necrosis of skeletal muscle, especially of the neck. At necropsy, up to 14 days after infection, the infected sheep exhibited striking pulmonary edema, edema of the subcutaneous tissues and fascial planes of the head and neck, and pleural and pericardial effusion of varying severity. A reliable model for experimental reproduction of fulminant BT in sheep will facilitate future studies to better characterize the pathogenesis of this disease, particularly as it regards the mechanisms responsible for the increased vascular permeability that characterizes BT and related orbiviral diseases such as African horse sickness.
Publisher: Elsevier BV
Date: 12-2012
DOI: 10.1016/J.VETMIC.2012.07.007
Abstract: Bluetongue virus (BTV) is the prototype member of the Orbivirus genus in the family Reoviridae and is the aetiological agent of the arthropod transmitted disease bluetongue (BT) that affects both ruminant and camelid species. The disease is of significant global importance due to its economic impact and effect on animal welfare. Bluetongue virus, a dsRNA virus, evolves through a process of quasispecies evolution that is driven by genetic drift and shift as well as intragenic recombination. Quasispecies evolution coupled with founder effect and evolutionary selective pressures has over time led to the establishment of genetically distinct strains of the virus in different epidemiological systems throughout the world. Bluetongue virus field strains may differ substantially from each other with regards to their phenotypic properties (i.e. virulence and/or transmission potential). The intrinsic molecular determinants that influence the phenotype of BTV have not clearly been characterized. It is currently unclear what contribution each of the viral genome segments have in determining the phenotypic properties of the virus and it is also unknown how genetic variability in the in idual viral genes and their functional domains relate to differences in phenotype. In order to understand how genetic variation in particular viral genes could potentially influence the phenotypic properties of the virus a closer understanding of the BTV virion, its encoded proteins and the evolutionary mechanisms that shape the ersity of the virus is required. This review provides a synopsis of these issues and highlights some of the studies that have been conducted on BTV and the closely related African horse sickness virus (AHSV) that have contributed to ongoing attempts to identify the molecular determinants that influence the virus' phenotype. Different strategies that can be used to generate BTV mutants in vitro and methods through which the causality between particular genetic modifications and changes in phenotype may be determined are also described. Finally ex les are highlighted where a clear understanding of the molecular determinants that influence the phenotype of the virus may have contributed to risk assessment and mitigation strategies during recent outbreaks of BT in Europe.
Publisher: Centers for Disease Control and Prevention (CDC)
Date: 12-2016
Publisher: Springer Science and Business Media LLC
Date: 26-09-2013
DOI: 10.1007/S00705-012-1478-5
Abstract: Bovine viral diarrhoea virus (BVDV) has emerged as one of the economically important pathogens in cattle populations, with a worldwide distribution and causing a complex of disease syndromes. Two genotypes, BVDV 1 and 2, exist and are discriminated on the basis of the sequence of the 5' non-coding region (5' NCR) using real-time PCR. Real-time PCR is more sensitive, specific, and less time-consuming than conventional PCR, and it has less risk of cross-contamination of s les. Limited information exists on BVDV genetic subtypes in South Africa. The aim of this study was to determine the genotypes of BVDV currently circulating in South African feedlots. A total of 279 specimens (219 tissue s les, 59 trans-tracheal aspirates and 1 blood s le) were collected from dead and living cattle with lesions or clinical signs compatible with BVDV infection. Pooled homogenates from the same animals were prepared, and total RNA was extracted. A screening test was performed on the pooled s les, and positive pools were investigated in idually. A Cador BVDV Type 1/2 RT-PCR Kit (QIAGEN, Hilden, Germany) was used for the real-time PCR assay on a LightCycler(®) V2.0 real-time PCR machine (Roche Diagnostics, Mannheim, Germany). The results were read at 530 and 640 nm for BVDV 1 and 2, respectively. Bovine viral diarrhoea virus was detected in a total of 103 s les that included 91 tissue s les, 1 blood s le and 11 trans-tracheal aspirates. Eighty-five (82.5 %) of the strains were genotype 1 and 18 (17.5 %) were genotype 2. Comparing the sequencing data, genotypes 1 and 2 from the field strains did not cluster with vaccine strains currently used in feedlots in South Africa. The present study revealed the presence of BVDV genotype 2 in cattle in South Africa based on the high sequence similarity between genotype 2 field strains and strain 890 from North America. The presence of genotype 2 viruses that phylogenetically belong to different clusters and coexist in feedlots is consistent with the possibility of multiple virus introductions. These results represent the first documented evidence for the presence of BVDV genotype 2 in African cattle.
Publisher: Hindawi Limited
Date: 05-01-2014
DOI: 10.1111/TBED.12045
Abstract: It is known that lumpy skin disease virus (LSDV) can be shed in bull semen following infection and also that artificial insemination (AI) poses a biosecurity risk. However, it is not known whether the use of LSDV infected semen in AI poses a biosecurity risk. The aim of this study was to investigate whether LSDV, transmitted through semen, can infect cows and their embryos. Two controlled trials were performed simultaneously. Eleven young beef heifers, naïve to LSDV, were synchronized using an OvSynch protocol and inseminated on Day 0 with fresh semen spiked with a field strain of LSDV on day 0. Six of the heifers were superovulated on Day 1 using pregnant mare serum gonadotropin, and embryos were flushed from these heifers on Day 6. Blood and serum s les were collected from Day 4 until Day 27 to determine the presence of LSDV by PCR and virus isolation, and the presence of antibodies against LSDV by SNT. The first clinical signs of LSD were noticed on Day 10, followed by severe generalized LSD in three heifers and mild LSD in two more heifers. Two heifers were humanely euthanized due to severe unresponsive stranguria. LSDV was detected by PCR, virus isolation or electron microscopy in blood, embryos and organs of experimentally infected animals and eight heifers had seroconverted by Day 27. Two control animals were not affected. This is the first report of experimental seminal transmission of LSDV in cattle.
Publisher: American Society for Microbiology
Date: 30-06-2020
Abstract: This is a report of the complete genome sequences of plaque-selected isolates of each of the five virus strains included in a South African commercial trivalent bluetongue virus (BTV) attenuated live virus vaccine, a BTV-4 field strain isolated from Rustenburg, South Africa, in 2011, and a bluetongue reassortant (bluetongue virus 4 strain 4/ O. aries -tc/ZAF/11/OBP-115) isolated from experimentally vaccinated cattle. Full-genome sequencing and phylogenetic analyses show that the bluetongue virus 9 strain 9/ B. taurus -tc/ZAF/15/Onderstepoort_B02b is a reassortant virus containing segments from both BTV-9 and BTV-8.
Publisher: Springer Science and Business Media LLC
Date: 2000
Abstract: The capture of free-living adults and nymphs of Amblyomma hebraeum, the main vector of heartwater in domestic and wild ruminants in South Africa, by means of attraction-aggregation-attachment-pheromone/carbon dioxide traps at five endemic localities in South Africa is described. Although the traps were used successfully at each of the localities, no determination of their efficiency in relation to the actual abundance of ticks at a particular site was made. This study confirmed that the traps could be used in a variety of ecological areas to locate populations of free-living adult A. hebraeum.
Publisher: Wiley
Date: 12-2002
DOI: 10.1046/J.1365-2915.2002.00385.X
Abstract: Equine encephalosis virus (EEV) is widespread and prevalent in southern Africa. In this study, the oral susceptibility of Culicoides (Avaritia) imicola Kieffer (Diptera: Ceratopogonidae) to EEV was confirmed. In addition, C. (A.) bolitinos Meiswinkel, collected in the high-lying eastern Free State, South Africa, was systemically infected with the Bryanston serotype of EEV after feeding through a membrane on artificially infected equine blood containing 4.7 log10 PFU/mL of EEV. The mean infectivity of Bryanston virus in C. bolitinos increased from 1.2 log10 PFU/midge, in midges assayed for virus immediately after feeding on the blood-virus mixture, to 3.1 log10 PFU/midge in midges assayed after 10 days' incubation at 23.5 degrees C. Elevated virus infectivity titres, found in in idual infected C. bolitinos, suggested that this Culicoides species is a vector of EEV. This bovine dung-breeding Culicoides species may play an important role in transmitting EEV in the cooler parts of southern Africa, where it can be the most abundant Culicoides species collected near livestock. In the present study the prevalence of infection obtained for C. bolitinos (2.2%) with the Bryanston serotype of EEV was significantly lower than that of C. imicola (18.4%). After incubation, the Bryanston serotype of EEV was also isolated from one of 110 C. onderstepoortensis Fiedler assayed. However, the virus titre in this midge was 1.2 log10 PFU/midge, which is not different from the titre that would be expected immediately after feeding on the blood-virus mixture. Culicoides species that survived the incubation period and that were negative for the presence of Bryanston virus were C. magnus Colaço (96), C. bedfordi Ingram & Macfie (95) and C. pycnostictus Ingram & Macfie (45).
Publisher: Elsevier BV
Date: 08-2013
DOI: 10.1016/J.TVJL.2013.01.005
Abstract: The capability of the recently emerged European strain of bluetongue virus serotype 8 (BTV-8) to cross the ruminant placenta has been established in experimental and field studies in both sheep and cattle. Seroprevalence rates in goats in North-Western Europe were high during the recent outbreak of BTV-8 however the capability of the virus to infect goats through the transplacental route has not been established. In the present study, four Saanen goats were inoculated with the European strain of BTV-8 at 62 days of gestation this resulted in mild clinical signs, however gross lesions observed post mortem were more severe. Viral RNA was detected by real-time RT-PCR in blood and tissue s les from three fetuses harvested from two goats at 43 days post infection. Conventional RT-PCR and genome sequencing targeting viral segment 2 confirmed infection of brain tissue with BTV-8 in two of these fetuses. In total, five of six fetuses demonstrated lesions that may have been associated with transplacental infection with BTV. Infected fetuses did not demonstrate neurological lesions. Low viral RNA concentrations in fetal blood and tissue further suggest that the infected fetuses would probably not have been born viraemic. The implications of these findings with regards to the epidemiology and overwintering of BTV-8 in Europe remains unclear.
Publisher: Medpharm Publications
Date: 04-10-2012
Abstract: In 2008, a suspected outbreak of Rift Valley fever (RVF) was reported on a farm in the Bela-Bela area, Limpopo Province, South Africa. Seven calves died on the affected dairy farm, where no RVF vaccination programme was practised. No apparent clinical disease was reported in the other 300 cattle (33 calves included) or 200 sheep on the farm. During the outbreak, blood s les from 77.7% (233/300) of the cattle and 36.5% (73/200) of the sheep were collected on the affected farm and 55 blood s les were taken from cattle on a neighbouring farm. Eight weeks later, 78% of the cattle (234/300) and 42.5% of the sheep (85/200) were bled on the affected farm only. All sera were tested by an Immunoglobulin M (IgM)-capture Enzymelinked immunosorbent assay (ELISA) and by an indirect Immunoglobulin G (IgG) ELISA. Selected IgM-positive (n = 14), IgG-positive (n = 23) and s les negative for both IgM and IgG-specific antibodies against RVF virus (n = 19) were tested using the serum neutralisation test (SNT). Sera from IgM-positive (n = 14) and negative (n = 20) animals were also tested by a TaqMan polymerase chain reaction (PCR). On the affected farm, 7% (16/233) of the cattle were IgM-positive and 13.7% (32/233) IgG-positive at the first bleed and 2% were IgM-positive at the second bleed, whilst the number of cattle positive for IgG-specific antibodies increased by 21.3% compared with the first bleed. Only 1.4% of sheep were positive for both IgM and IgG antibodies at the first collection at the second bleed, IgM-positive cases decreased to 1.2%, whilst IgG-positive cases increased to 2.4%. Whilst no IgM-positive cattle were found on the neighbouring farm, 5.5% of cattle were IgG-positive. The SNT confirmed most of the ELISA results, whilst PCR results were all negative. Although serology results indicated virus circulation on both farms, the negative PCR results demonstrated that the animals were not viraemic at the time they were s led. The movement of infected mosquito vectors by wind over long distances into a low-lying area that favoured their breeding on the Bela-Bela farm may have led to an outbreak of the disease there, but the reason for the low level of virus circulation amongst susceptible animals remains unclear.
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.TTBDIS.2013.09.010
Abstract: Lumpy skin disease (LSD) is caused by lumpy skin disease virus (LSDV), a member of the genus Capripoxvirus. Transmission of the virus has been associated with haematophagous insects such as Stomoxys calcitrans as well as Aedes and Culex species of mosquitoes. Recent studies have reported the transmission of the virus by Amblyomma hebraeum, Rhipicephalus appendiculatus, and Rhipicephalus decoloratus ticks and the presence of LSDV in saliva of A. hebraeum and R. appendiculatus ticks. The aim of this study was to determine which tick organs become infected by LSDV following intrastadial infection and transstadial persistence of the virus in A. hebraeum and R. appendiculatus ticks. Nymphal and adult ticks were orally infected by feeding them on LSDV-infected cattle. Partially fed adult ticks were processed for testing while nymphs were fed to repletion and allowed to moult to adults before being processed for testing. The infection in tick organs was determined by testing for the presence of the viral antigen using monoclonal antibodies with immunohistochemical staining. The viral antigen was detected in salivary glands, haemocytes, synganglia, ovaries, testes, fat bodies, and midgut. Since the virus was shown to be able to cross the midgut wall and infect various tick organs, this may indicate potential for biological development and transmission of LSDV in ticks. This study strengthens the previously reported evidence of the occurrence of LSDV in tick saliva.
Publisher: MDPI AG
Date: 08-05-2021
Abstract: Vaccines form the cornerstone of any control, eradication and preventative strategy and this is no different for lumpy skin disease. However, the usefulness of a vaccine is determined by a multiplicity of factors which include stability, efficiency, safety and ease of use, to name a few. Although the vaccination c aign in the Balkans against lumpy skin disease virus (LSDV) was successful and has been implemented with success in the past in other countries, data of vaccine failure have also been reported. It was therefore the purpose of this study to compare five homologous live attenuated LSDV vaccines (LSDV LAV) in a standardized setting. All five LSDV LAVs studied were able to protect against a challenge with virulent LSDV. Aside from small differences in serological responses, important differences were seen in side effects such as a local reaction and a Neethling response upon vaccination between the analyzed vaccines. These observations can have important implications in the applicability in the field for some of these LSDV LAVs.
Publisher: Medpharm Publications
Date: 03-08-2012
Abstract: Recent outbreaks of bluetongue virus (BTV) serotypes 2 and 8 in many European countries provided an opportunity to investigate the possibility of improving the safety of the modified live vaccines administered mainly in South Africa. Modified live vaccines (MLV) released at a titre of 5 x 104 PFU/mL, raised concerns and prompted the need to determine the minimum titre which will still be protective and also safe. The BTV serotypes 2 and 8 vaccines were produced at the following titres: 102 PFU/mL, 103 PFU/mL and 104 PFU/mL, and were injected into 24 sheep which were then monitored. Blood was collected on days 0, 3, 6, 9, 12, 15, 18, 21, 25, 28 and 4 months post vaccination, for seroconversion and viraemia studies. These sheep were later challenged at 4 months post vaccination using BTV infected cell culture material, they were then observed and bled and again tested for viraemia. There was no viraemia post vaccination, however, a febrile reaction did occur and seroconversion was demonstrated at low titres for both BTV 2 and 8. Although viraemia was demonstrated post challenge, sheep vaccinated with the low titre BTV 2 vaccine showed more than a 90% protection index at a lower titre of 103 PFU/mL, compared with BTV 8 that showed a protection index above 90% at all the titres used. It is recommended that for BTV 2 vaccine, sheep should be vaccinated at a titre of 103 PFU/mL and at a titre of 102 PFU/mL with BTV 8 vaccine.
Publisher: Public Library of Science (PLoS)
Date: 18-07-2018
Publisher: Elsevier BV
Date: 1993
DOI: 10.1016/0959-8049(93)90020-G
Abstract: To search for a reliable proliferation marker in epithelial head and neck lesions, we have analysed the expression of the histone H3 gene by in situ hybridisation and compared this with the immunoreactivity of the widely used monoclonal antibody Ki-67. In many lesions, the Ki-67 staining failed to delineate proliferation. In contrast, the H3 hybridisation signals were in accordance with the histopathology of the biopsies: in hyperplastic epithelia, significant H3 mRNA levels were only seen in areas with inflammation. Dysplastic cells showed distinctly elevated H3 expression. Benign and semi-malignant tumours, i.e. basal cell carcinomas, showed moderate H3 signals at the periphery. In squamous cell carcinomas, H3 expression was always high at the expanding zone of the tumour and was most extensive in undifferentiated carcinomas. Thus, the expression of the histone H3 gene closely reflected the dynamics of neoplastic growth within and around head and neck tumours.
No related grants have been discovered for Estelle Venter.