ORCID Profile
0000-0002-4321-8873
Current Organisations
Austral University of Chile
,
University of Melbourne
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Publisher: Springer Science and Business Media LLC
Date: 13-12-2019
Publisher: PeerJ
Date: 21-03-2022
DOI: 10.7717/PEERJ.12924
Abstract: Perennial ryegrass ( Lolium perenne L.) possesses a high level of nutritional quality and is widely used as a forage species to establish permanent pastures in southern Chile. However, the productivity of most such pastures is limited by various environmental agents, such as insect pests and drought. In this context, our work stresses the need for elucidating the ability of fungal endophytes to establish interactions with plants, and to understand how these processes contribute to plant performance and fitness. Therefore, we evaluated the colonization and impact of two native strains of the endophytic insect-pathogenic fungus (EIPF) group isolated from permanent ryegrass pastures in southern Chile. Roots and seeds of ryegrass and scarabaeid larvae were collected from nine different ryegrass pastures in the Los Ríos region of southern Chile to specifically isolate EIPFs belonging to the genera Beauveria and Metarhizium . Fungal isolations were made on 2% water agar with antibiotics, and strains were identified by analyzing the entire internal transcribed spacer (ITS) 1-5.8S-ITS2 ribosomal DNA region. Four strains of Beauveria and 33 strains of Metarhizium were isolated only in scarabaeid larvae from ryegrass pastures across four sites. Experimental mini-pastures that were either not inoculated (control) or co-inoculated with conidia of the strains Beauveria vermiconia NRRL B-67993 (P55_1) and Metarhizium aff. lepidiotae NRRL B-67994 (M25_2) under two soil humidity levels were used. Ryegrass plants were randomly collected from the mini-pastures to characterize EIPF colonization in the roots by real-time PCR and fluorescence microscopy. Aboveground biomass was measured to analyze the putative impact of colonization on the mini-pastures’ aboveground phenotypic traits with R software using a linear mixed-effects model and the ANOVA statistical test. Seasonal variation in the relative abundance of EIPFs was observed, which was similar between both strains from autumn to spring, but different in summer. In summer, the relative abundance of both EIPFs decreased under normal moisture conditions, but it did not differ significantly under water stress. The aboveground biomass of ryegrass also increased from autumn to spring and decreased in summer in both the inoculated and control mini-pastures. Although differences were observed between moisture levels, they were not significant between the control and inoculated mini-pastures, except in July (fresh weight and leaf area) and October (dry weight). Our findings indicate that native strains of B. vermiconia NRRL B-67993 (P55_1) and M . aff. lepidiotae NRRL B-67994 (M25_2) colonize and co-exist in the roots of ryegrass, and these had little or no effect on the mini-pastures’ aboveground biomass however, they could have other functions, such as protection against root herbivory by insect pests.
Publisher: Elsevier BV
Date: 03-2021
Publisher: SciELO Agencia Nacional de Investigacion y Desarrollo (ANID)
Date: 2015
Publisher: Cold Spring Harbor Laboratory
Date: 03-06-2020
DOI: 10.1101/2020.05.30.20117721
Abstract: Effective interventions are mandatory to control the transmission and spread of SARS-CoV-2, a highly contagious virus causing devastating effects worldwide. Cost-effective approaches are pivotal tools required to increase the detection rates and escalate further in massive surveillance programs, especially in countries with limited resources that most of the efforts have focused on symptomatic cases only. Here, we compared the performance of the RT-qPCR using an intercalating dye with the probe-based assay. Then, we tested and compared these two RT-qPCR chemistries in different pooling systems: after RNA extraction (post-RNA extraction) and before RNA extraction (pre-RNA extraction) optimizing by pool size and template volume. We evaluated these approaches in 610 clinical s les. Our results show that the dye-based technique has a high analytical sensitivity similar to the probe-based detection assay used worldwide. Further, this assay may also be applicable in testing by pool systems post-RNA extraction up to 20 s les. However, the most efficient system for massive surveillance, the pre-RNA extraction pooling approach, was obtained with the probe-based assay in test up to 10 s les adding 13.5 µL of RNA template. The low cost and the potential use in pre-RNA extraction pool systems, place of this assays as a valuable resource for scalable s ling to larger populations. Implementing a pool system for population s ling results in an important savings of laboratory resources and time, which are two key factors during an epidemic outbreak. Using the pooling approaches evaluated here, we are confident that it can be used as a valid alternative assay for the detection of SARS-CoV-2 in human s les.
Publisher: Elsevier BV
Date: 09-2018
DOI: 10.1016/J.VACCINE.2018.08.012
Abstract: Recombination is closely linked with virus replication and is an important mechanism that contributes to genome ersification and evolution in alphaherpesviruses. Infectious laryngotracheitis (ILTV Gallid alphaherpesvirus 1) is an alphaherpesvirus that causes respiratory disease in poultry. In the past, natural (field) recombination events between different strains of ILTV generated virulent recombinant viruses that have caused severe disease and economic loss in poultry industries. In this study, chickens were vaccinated with attenuated ILTV vaccines to examine the effect of vaccination on viral recombination and ersity following subsequent co-inoculation with two field strains of ILTV. Two of the vaccines (SA2 and A20) prevented ILTV replication in the trachea after challenge, but the level of viral replication after co-infection in birds that received the Serva ILTV vaccine strain did not differ from that of the mock-vaccinated (control) birds. Even though the levels of viral replication were similar in the two groups, the number of recombinant progeny viruses and the level of viral ersity were significantly lower in the Serva-vaccinated birds than in mock-vaccinated birds. In both the mock-vaccinated and Serva-vaccinated groups, a high proportion of recombinant viruses were detected in naïve in-contact chickens that were housed with the co-inoculated birds. Our results indicate that vaccination can limit the number and ersity of recombinant progeny viruses in a manner that is independent of the level of virus replication. It is possible that immune responses induced by vaccination can select for virus genotypes that replicate well under the pressure of the host immune response.
Publisher: Elsevier BV
Date: 09-2023
Publisher: American Society for Microbiology
Date: 12-2018
DOI: 10.1128/AEM.01822-18
Abstract: Recombination allows alphaherpesviruses to evolve over time and become more virulent. Historically, characterization of viral vaccines in poultry have mainly focused on limiting clinical disease, rather than limiting virus replication, but such approaches can allow field viruses to persist and evolve in vaccinated populations. In this study, we vaccinated chickens with Gallid alphaherpesvirus 1 vaccines that are commercially available in the United States and then performed coinoculations with two field strains of virus to measure the ability of the vaccines to prevent field strains from replicating and recombining. We found that vaccination reduced viral replication, recombination, and ersity compared to those in unvaccinated chickens, although the extent to which this occurred differed between vaccines. We suggest that characterization of vaccines could include studies to examine the ability of vaccines to reduce viral recombination in order to limit the rise of new virulent field strains due to recombination, especially for those vaccines that are known not to prevent viral replication following challenge.
Publisher: Elsevier BV
Date: 07-2014
DOI: 10.1016/J.VETIMM.2014.04.003
Abstract: Immunosuppression during the calving period in dairy cows is associated with an increased risk of diseases. Correct neutrophil function is a key mechanism of innate immunity that is used to protect the host from pathogenic microorganisms. The aim of this study was to evaluate the function of blood neutrophils obtained from heifers between 30 days preparturition and 30 days postparturition. We assessed the phagocytosis of fluorescent bioparticles using flow cytometry, chemotaxis induced by chemoattractants using the transwell plate assay, lactoferrin release using ELISA and cyclooxygenase-2 (COX-2) gene expression using real time-PCR. Our results showed an increased ability of phagocytosis of bioparticles and chemotaxis induced by the chemotactic agent platelet activating factor (PAF), between day 15 preparturition until day 30 postparturition, and at calving, respectively. COX-2 gene expression induced by PAF was increased only in neutrophils obtained at days 30 pre- and post-parturition (p<0.001). Neutrophil lactoferrin release was reduced between day 15 preparturition and day 30 postparturition compared with that at day 30 preparturition. Furthermore, lactoferrin plasma levels were increased at calving. In conclusion, we provided evidence that neutrophils from heifers around calving time exhibit impairment of particular defensive functions, such as COX-2 mRNA expression and lactoferrin, suggesting that these mechanisms may contribute to immunosuppression in cows around calving.
Publisher: Elsevier BV
Date: 09-2023
Publisher: Public Library of Science (PLoS)
Date: 06-12-2018
Publisher: American Society for Microbiology
Date: 27-04-2023
DOI: 10.1128/JVI.01406-22
Abstract: Infectious laryngotracheitis virus (ILTV) is an important pathogen of chicken with morbidity of 100% and mortality rates as high as 70%. Factoring in decreased production, mortality, vaccination, and medication, a single outbreak can cost producers over a million dollars.
Publisher: Elsevier BV
Date: 11-2018
DOI: 10.1016/J.FSI.2018.08.042
Abstract: Eleginops maclovinus is a eurythermic fish that under natural conditions lives in environments with temperatures ranging from 4 to 18 °C and can be usually captured near salmon farming areas. The aim of this study was to evaluate the effect of temperature over the innate and adaptive immune response of E. maclovinus challenged with Piscirickettsia salmonis following different treatments: C (control injection with culture medium at 12 °C), C+ (bacterial injection at 12 °C), 18 °C c/A + B (injection with culture medium in acclimation at 18 °C), 18 °C c/A + B (bacterial injection in acclimation at 18 °C), 18 °C s/A + M (injection with culture medium without acclimation at 18 °C) and 18 °C s/A + B (bacterial injection without acclimation at 18 °C). Each injection had 100 μL of culture medium or with 100 μL at a concentration 1 × 10
Publisher: Elsevier BV
Date: 04-2018
Publisher: Elsevier BV
Date: 04-2017
DOI: 10.1016/J.MEEGID.2016.12.022
Abstract: Recombination in alphaherpesviruses was first described more than sixty years ago. Since then, different techniques have been used to detect recombination in natural (field) and experimental settings. Over the last ten years, next-generation sequencing (NGS) technologies and bioinformatic analyses have greatly increased the accuracy of recombination detection, particularly in field settings, thus contributing greatly to the study of natural alphaherpesvirus recombination in both human and veterinary medicine. Such studies have highlighted the important role that natural recombination plays in the evolution of many alphaherpesviruses. These studies have also shown that recombination can be a safety concern for attenuated alphaherpesvirus vaccines, particularly in veterinary medicine where such vaccines are used extensively, but also potentially in human medicine where attenuated varicella zoster virus vaccines are in use. This review focuses on the contributions that NGS and sequence analysis have made over the last ten years to our understanding of recombination in mammalian and avian alphaherpesviruses, with particular focus on attenuated live vaccine use.
Publisher: Cold Spring Harbor Laboratory
Date: 30-04-2021
DOI: 10.1101/2021.04.30.442100
Abstract: Infectious bronchitis virus (IBV), an avian coronavirus, can be isolated and cultured in tracheal organ cultures (TOCs), embryonated eggs and cell cultures. TOCs and embryonated eggs are commonly used for viral isolation but use of these is laborious and expensive. Cell cultures have been used only with IBV strains that have previously been adapted to grow under laboratory conditions, and not for primary isolation. Previous studies using the coronavirus porcine epidemic diarrhoea virus (PEDV) have suggested that foetal bovine serum (FBS), a common component of cell culture media, can inhibit the adsorption of coronaviruses onto the host cell membrane receptors. In the present study, the replication of IBV in primary chicken embryo kidney (CEK) cell cultures and the Leghorn hepatocellular carcinoma (LMH) cell line was examined using two different cell culture media, one containing FBS and the other containing yeast extract (YE). A reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) assay was used to quantify viral RNA copies in cell lysates. The highest concentrations of viral genomes were observed when the cell culture medium did not contain FBS. Examination of the infectivity of virus grown in CEK cell cultures was examined by titration in embryonated chicken eggs, demonstrating that the cell lysate from CEK cell cultures in medium without FBS contained a higher median embryo infectious dose (EID 50 ) than that from CEK cell cultures in medium containing FBS. These results suggest that improved replication of IBV in cell cultures can be achieved by the omission of FBS from the cell culture medium. This may enhance the potential for production of vaccines in cell culture and facilitate the isolation of emergent IBV strains in cell cultures.
Publisher: Elsevier BV
Date: 12-2023
Publisher: Springer Science and Business Media LLC
Date: 21-10-2022
DOI: 10.1007/S42770-022-00833-Y
Abstract: Avian infectious laryngotracheitis (ILT) is a respiratory disease that causes severe economic losses in the poultry industry, mainly due to high morbidity and mortality and reduced egg production. Molecular characterization was performed on s les collected from flocks in the Brazilian States of São Paulo, Pernambuco, and Minas Gerais during 2015 and 2016 that presented clinical signs of respiratory disease. End-point PCR was used for viral detection, and DNA sequencing was used for differentiation of vaccine and field strains. Molecular analysis based on the infected cell protein (ICP4) gene separated four of the nine s les together with previous Brazilian isolates (São Paulo and Minas Gerais), one s le was grouped on the same branch as Minas Gerais strains (along with another related s le), one s le was separately branched but still related to the tissue culture origin (TCO) vaccine strain, and two s les were grouped on the same branch as the TCO vaccine strain. Molecular analysis of the thymidine kinase (TK) gene showed the existence of strains of both high and low virulence. The characterization of two fragments of the ICP4 gene and a fragment of the TK gene in this study suggested that the virus circulating in Guatapará, as well as those in Barretos and Itanhandu, that is causing respiratory problems in birds is a highly virulent field strain. The clinical signs point to a TCO vaccine strain that most likely underwent some reversal event and is a latent reactivated infection.
Publisher: Public Library of Science (PLoS)
Date: 28-03-2017
Publisher: American Society for Microbiology
Date: 12-2017
DOI: 10.1128/AEM.01532-17
Abstract: Recombination is a feature of many alphaherpesviruses that infect people and animals. Infectious laryngotracheitis virus (ILTV Gallid alphaherpesvirus 1 ) causes respiratory disease in chickens, resulting in significant production losses in poultry industries worldwide. Natural (field) ILTV recombination is widespread, particularly recombination between attenuated ILTV vaccine strains to create virulent viruses. These virulent recombinants have had a major impact on animal health. Recently, the development of a single nucleotide polymorphism (SNP) genotyping assay for ILTV has helped to understand ILTV recombination in laboratory settings. In this study, we applied this SNP genotyping assay to further examine ILTV recombination in the natural host. Following coinoculation of specific-pathogen-free chickens, we examined the resultant progeny for evidence of viral recombination and characterized the ersity of the recombinants over time. The results showed that ILTV replication and recombination are closely related and that the recombinant viral progeny are most erse 4 days after coinoculation, which is the peak of viral replication. Further, the locations of recombination breakpoints in a selection of the recombinant progeny, and in field isolates of ILTV from different geographical regions, were examined following full-genome sequencing and used to identify recombination hot spots in the ILTV genome. IMPORTANCE Alphaherpesviruses are common causes of disease in people and animals. Recombination enables genome ersification in many different species of alphaherpesviruses, which can lead to the evolution of higher levels of viral virulence. Using the alphaherpesvirus infectious laryngotracheitis virus (ILTV), we performed coinfections in the natural host (chickens) to demonstrate high levels of virus recombination. Higher levels of ersity in the recombinant progeny coincided with the highest levels of virus replication. In the recombinant progeny, and in field isolates, recombination occurred at greater frequency in recombination hot spot regions of the virus genome. Our results suggest that control measures that aim to limit viral replication could offer the potential to limit virus recombination and thus the evolution of virulence. The development and use of vaccines that are focused on limiting virus replication, rather than vaccines that are focused more on limiting clinical disease, may be indicated in order to better control disease.
No related grants have been discovered for Carlos Loncoman.