ORCID Profile
0000-0002-3705-4526
Current Organisation
University of Adelaide
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Publisher: Springer Science and Business Media LLC
Date: 02-08-2013
Publisher: Scholar Science Journals
Date: 04-2013
Publisher: Springer Science and Business Media LLC
Date: 12-2014
Publisher: Hindawi Limited
Date: 20-06-2013
DOI: 10.1155/2013/308204
Abstract: Background . Transfusion associated bacterial infection has remained more frequent with a sever risk of morbidity and mortality. This study assessed the bacteriological safety of blood collected for transfusion. Method . A cross-sectional study was conducted at University of Gondar hospital blood bank from December 2011 to June 2012. Bacterial isolation, identification, and antimicrobial susceptibility tests were done as per the standard procedure. Chi-square test and P value were used to assess associations between risk factors and the bacterial isolation rate. Results . Twenty-one (15.33%) blood units were found contaminated with bacteria, and 95.24% contamination was due to external sources. The commonly isolated bacteria were Staphylococcus aureus , Coagulase negative Staphylococci , Escherichia coli , Klebsiella species, Streptococci species, Enterobacter species, and Citrobacter species. All of the bacteria isolated were 100% sensitive to Gentamicin, Chlor henicol, Amoxicillin, and Doxycycline. Multiple antimicrobial resistances were observed in 66.7% of the isolates. Not using glove by phlebotomist, touching disinfected phlebotomy site and double puncture at the same hand or both hands of a donor were found to be risk factors for bacterial contamination. Conclusion . Bacterial contamination of blood to be transfused is a common problem in the hospital. So attention should be given to activities performed at the blood bank for safe transfusion practices.
Publisher: Cold Spring Harbor Laboratory
Date: 03-08-2021
DOI: 10.1101/2021.07.30.21261234
Abstract: Increasing evidence suggests immune dysregulation in in iduals recovering from SARS- CoV-2 infection. We have undertaken an integrated analysis of immune responses at a transcriptional, cellular, and serological level at 12, 16, and 24 weeks post-infection (wpi) in 69 in iduals recovering from mild, moderate, severe, or critical COVID-19. Anti-Spike and anti-RBD IgG responses were largely stable up to 24wpi and correlated with disease severity. Deep immunophenotyping revealed significant differences in multiple innate (NK cells, LD neutrophils, CXCR3 + monocytes) and adaptive immune populations (T helper, T follicular helper and regulatory T cells) in COVID-19 convalescents compared to healthy controls, which were most strongly evident at 12 and 16wpi. RNA sequencing suggested ongoing immune and metabolic dysregulation in convalescents months after infection. Variation in the rate of recovery from infection at a cellular and transcriptional level may explain the persistence of symptoms associated with long COVID in some in iduals.
Publisher: Frontiers Media SA
Date: 03-04-2019
Publisher: Springer Science and Business Media LLC
Date: 12-2014
Publisher: Elsevier BV
Date: 05-2016
DOI: 10.1016/J.JIPH.2015.10.015
Abstract: Food borne pathogens are major causes of deaths, illnesses and billions of dollars of expenses. The burden of food borne illness is worsened by the ever increasing rate of antimicrobial resistance microbes. Shigella, a bacterial pathogen associated with food, is reported to account for higher prevalence rates of food borne illness in different settings. A cross-sectional study was conducted from February 10 to June 30, 2013, at the butcher houses of Gondar town in the Northwest of Ethiopia to assess the prevalence and antimicrobial susceptibility pattern of Shigella. Cattle raw meat and swab s les from selected critical control points, including knives, chopping boards, and the hands and noses of butchers, were collected and analyzed. The identification of Shigella was carried out using colony characteristics, the Gram reaction, and biochemical tests. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disc diffusion method. The overall hygienic status of the butcher shops was also assessed using a checklist. An observational analysis revealed that the sanitary condition of the butcher shops and their premises was poor. Of 306 s les screened, 10.5% were positive for Shigella. Approximately 7.4% of meat s les and 10.2% of swab s les were contaminated with Shigella. Out of the total Shigella isolates, 90.6%, 46.9%, 18.8% and 9.4% were resistant to icillin, amoxicillin, ceftriaxone and tetracycline, respectively. A multidrug resistance pattern was recorded in 27.8% of the isolates. In conclusion, the safety of meat sold at Gondar butchers houses was poor. The identified Shigella isolates showed high levels of drug resistance and multidrug resistance patterns for commonly used antimicrobials in veterinary and human medicine. Practicing wise use of antimicrobials and strict sanitary interventions at different critical control points is strongly recommended, in addition to further in-depth studies to prevent unprecedented consequences from shigellosis.
Publisher: Springer Science and Business Media LLC
Date: 17-01-2013
Publisher: MDPI AG
Date: 29-01-2020
Abstract: Despite direct acting antivirals (DAAs) curing % of in iduals infected with hepatitis C (HCV), in order to achieve the World Health Organization HCV Global Elimination Goals by 2030 there are still major challenges that need to be overcome. DAAs alone are unlikely to eliminate HCV in the absence of a vaccine that can limit viral transmission. Consequently, a prophylactic HCV vaccine is necessary to relieve the worldwide burden of HCV disease. DNA vaccines are a promising vaccine platform due to their commercial viability and ability to elicit robust T-cell-mediated immunity (CMI). We have developed a novel cytolytic DNA vaccine that encodes non-structural HCV proteins and a truncated mouse perforin (PRF), which is more immunogenic than the respective canonical DNA vaccine lacking PRF. Initially we assessed the ability of the HCV pNS3-PRF and pNS4/5-PRF DNA vaccines to elicit robust long-term CMI without any adverse side-effects in mice. Interferon-γ (IFN-γ) enzyme-linked immunosorbent spot (ELISpot) assay was used to evaluate CMI against NS3, NS4 and NS5B in a dose-dependent manner. This analysis showed a dose-dependent bell-curve of HCV-specific responses in vaccinated animals. We then thoroughly examined the effects associated with reactogenicity of cytolytic DNA vaccination with the multi-antigenic HCV DNA vaccine (pNS3/4/5B). Hematological, biochemical and histological studies were performed in male Sprague Dawley rats with a relative vaccine dose 10–20-fold higher than the proposed dose in Phase I clinical studies. The vaccine was well tolerated, and no toxicity was observed. Thus, the cytolytic multi-antigenic DNA vaccine is safe and elicits broad memory CMI.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-12-2019
Abstract: A novel T cell–based ZIKV vaccine, encoding NS1 protein, confers protection against systemic infection.
Publisher: Diva Enterprises Private Limited
Date: 2013
Publisher: Informa UK Limited
Date: 06-2015
DOI: 10.2147/HIV.S81481
Publisher: Springer Science and Business Media LLC
Date: 19-08-2011
Abstract: Salmonella are the major pathogenic bacteria in humans as well as in animals. Salmonella species are leading causes of acute gastroenteritis in several countries and salmonellosis remains an important public health problem worldwide, particularly in the developing countries. The situation is more aggravated by the ever increasing rate of antimicrobial resistance strains. Cattle have been implicated as a source of human infection with antimicrobial resistant Salmonella through direct contact with livestock and through the isolation of antimicrobial resistant Salmonella from raw milk, cheddar cheese, and hamburger meat traced to dairy farms. Despiite the presence of many studies on the prevalence and antimicrobial susceptibility pattern of Salmonella in Ethiopia, nothing has been said on the degree of the situation among apparently healthy lactating cows and in contact humans. Hence this study was conducted to determine the prevalence and antimicrobial resistance pattern of Salmonella isolates from lactating cows and in contact humans in dairy farms of Addis Ababa. a cross sectional study was conducted in Addis Ababa by collecting milk and faecal s les from lactating cows and stool s les from humans working in dairy farms. S les were pre-enriched in buffered peptone water followed by selective enrichment using selenite cysteine and Rapaport-Vassilidis broths. Isolation and identification was made by inoculating the selectively enriched s le on to Xylose Lysine Deoxycholate agar followed by confirmation of presumptive colonies using different biochemical tests. The Kibry Bauer disk diffusion method was used for antimicrobial sensitivity testing. 10.7% (21/195) of cows and 13.6% (3/22) of the human subjects sheded Salmonella . 83% resistance to two or more antimicrobials and 100% resistance to icillin were observed. Most of the isolates were relatively sensitive to ciprofloxacin, cotrimoxazole, and chlor henicol. High proportion of Salmonella isolates developed resistance to the commonly prescribed antimicrobials and this may be a considerable risk in the treatment of clinical cases. So, wise use of antimicrobials must be practiced to combat the ever increasing situation of antimicrobial resistance.
Publisher: Springer Science and Business Media LLC
Date: 09-07-2011
Publisher: Cold Spring Harbor Laboratory
Date: 11-11-2021
DOI: 10.1101/2021.11.08.21266035
Abstract: The duration and magnitude of SARS-CoV-2 immunity after infection, especially with regard to the emergence of new variants of concern (VoC), remains unclear. Here, immune memory to primary infection and immunity to VoC was assessed in mild-COVID-19 convalescents one year after infection and in the absence of viral re-exposure or COVID-19 vaccination. Serum and PBMC were collected from mild-COVID-19 convalescents at ∼6 and 12 months after a COVID-19 positive PCR (n=43) and from healthy SARS-CoV-2-seronegative controls (n=15-40). Serum titers of RBD and Spike-specific Ig were quantified by ELISA. Virus neutralisation was assessed against homologous, pseudotyped virus and homologous and VoC live viruses. Frequencies of Spike and RBD-specific memory B cells were quantified by flow cytometry. Magnitude of memory T cell responses was quantified and phenotyped by activation-induced marker assay, while T cell functionality was assessed by intracellular cytokine staining using peptides specific to homologous Spike virus antigen and four VoC Spike antigens. At 12 months after mild-COVID-19, % of convalescents remained seropositive for RBD-IgG and 88.9% had circulating RBD-specific memory B cells. Despite this, only 51.2% convalescents had serum neutralising activity against homologous live-SARS-CoV-2 virus, which decreased to 44.2% when tested against live B.1.1.7, 4.6% against B.1.351, 11.6% against P.1 and 16.2%, against B.1.617.2 VoC. Spike and non-Spike-specific T cells were detected in % of convalescents with frequency values higher for Spike antigen (95% CI, 0.29-0.68% in CD4 + and 0.11-0.35% in CD8 + T cells), compared to non-Spike antigens. Despite the high prevalence and maintenance of Spike-specific T cells in Spike ‘high-responder’ convalescents at 12 months, T cell functionality, measured by cytokine expression after stimulation with Spike epitopes corresponding to VoC was severely affected. SARS-CoV-2 immunity is retained in a significant proportion of mild COVID-19 convalescents 12 months post-infection in the absence of re-exposure to the virus. Despite this, changes in the amino acid sequence of the Spike antigen that are present in current VoC result in virus evasion of neutralising antibodies, as well as evasion of functional T cell responses. This work was funded by project grants from The Hospital Research Foundation and Women’s and Children’s Hospital Foundation, Adelaide, Australia. MGM is THRF Early Career Fellow. BGB is THRF Mid-Career Fellow. This project has been supported partly with Federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, under Contract No. 75N93021C00016 to A.S. and Contract No. 75N9301900065 to A.S, D.W. We regularly searched on PubMed and Google Scholar in June-October 2021 using in idual or combinations of the terms “long-term immunity”, “SARS-CoV-2”, “antigenic breadth”, “variant of concern” and “COVID-19”. We found studies that had assessed immune correlates at multipe time points after COVID-19 disease onset in convalescents, but not the antigenic breadth of T cells and antibodies and not in relation to VoC. Other immune studies in virus naive vaccinees, or vaccinated convalescents evaluated VoC-specific immunity, but not in convalescents that have not been vaccinated. In summary, we could not find long-term studies providing and in-depth evaluation of functionality of humoral and cell-mediated immunity, combined with addressing the adaptability of these immune players to VoC. The window of opportunity to conduct studies in COVID-19 convalescents (i.e. natural immunity to SARS-CoV-2) is closing due to mass vaccination programs. Here, in a cohort of unvaccinated mild-COVID-19 convalescents, we conducted a comprehensive, longitudinal, long-term immune study, which included functional assays to assess immune fitness against antigenically different VoC. Importantly, the cohort resided in a SARS-CoV-2-free community for the duration of the study with no subsequent re-exposure or infection. Our findings reveal a deeply weakened humoral response and functional vulnerability of T cell responses to VoC Spike antigens. This study provides a valuable snapshot of the quality of SARS-CoV-2 natural immunity and its durability in the context of a pandemic in which new variants continuously emerge and challenge pre-existing immune responses in convalescents and vacinees. Our results serve as a warning that delays in vaccination programs could lead to an increase in re-infection rates of COVID-19 convalescents, caused by virus variants that escape humoral and cell-mediated immune responses. Furthermore, they reinforce the potential benefit of booster vaccination that is tuned to the active variants.
Publisher: ScopeMed
Date: 2013
Publisher: Springer Science and Business Media LLC
Date: 25-05-2013
Publisher: Springer Science and Business Media LLC
Date: 10-02-2014
Publisher: Springer Science and Business Media LLC
Date: 24-09-2015
Publisher: Oxford University Press (OUP)
Date: 09-2013
Publisher: Frontiers Media SA
Date: 24-11-2020
DOI: 10.3389/FMICB.2020.559105
Abstract: A vaccine that induces potent, broad and sustained cell-mediated immunity, resulting in effective memory has the potential to restrict hepatitis C (HCV) virus infection. Early, multi-functional CD4 + and CD8 + T cell responses against non-structural protein 3 (NS3) have been associated with HCV clearance. Necrotic cells generate strong immune responses and represent a major antigenic source used by dendritic cells (DC) for processing and presentation, but there is conflicting evidence as to their immunogenicity in vaccination. Immunization with DC loaded with viral antigens has been done in the past, but to date the immunogenicity of live vs. necrotic DC vaccines has not been investigated. We developed a DC2.4 cell line stably expressing HCV NS3, and compared the NS3-specific responses of live vs. necrotic NS3 DC. Vaccination of mice with necrotic NS3 DC increased the breadth of T-cell responses and enhanced the production of IL-2, TNF-α, and IFN-γ by effector memory CD4 + and CD8 + T cells, compared to mice vaccinated with live NS3 DC. A single dose of necrotic NS3 DC vaccine induced a greater influx and activation of cross-presenting CD11c + CD8α + DC and necrosis-sensing Clec9A + DC in the draining lymph nodes. Furthermore, using a hydrodynamic challenge model necrotic NS3 DC vaccination resulted in enhanced clearance of NS3-positive hepatocytes from the livers of vaccinated mice. Taken together, the data demonstrate that necrotic DC represent a novel and exciting vaccination strategy capable of inducing broad and multifunctional T cell memory.
Publisher: Springer Science and Business Media LLC
Date: 25-10-2012
Abstract: Data on lipid profile abnormalities among patients receiving highly active antiretroviral treatment in Ethiopia are very limited. The aim of this study was to determine the prevalence of dyslipidemia and characteristics of lipid profiles among patients living with human immunodeficiency virus (HIV) using first-line highly active antiretroviral therapy (HAART) in Southern Ethiopia. This cross sectional comparative group study was conducted between March and May 2012, and included 113 HIV infected patients treated for a minimum of one year with first-line HAART regimens that included Efavirenz and Nevirapine (HAART group) and others 113 who had never received HAART (pre-HAART group). Serum lipid profiles were determined after overnight fasting and dyslipidemia was assessed according to the United State National Cholesterol Education program-III guideline. For statistical analysis Chi-square, student’s t-test, and logistic regression were used using Statistical Package for Social Sciences (SPSS) Version 20. Ninety-three (82.3%) of HAART and 87 (76.9%) pre-HAART patients had at least one laboratory abnormality, which is compatible with a diagnosis of dyslipidemia. Total cholesterol ≥ 200 mg/dl occurred in 43.4% of HAART and 15.9% pre-HAART patients (p= .0001), whereas HDL-cholesterol below 40 mg/dl occurred in 43.4% and in 63.7% respectively, (p=0.002). The LDL-cholesterol ≥ 130 mg/dl occurred in 33.6% of HAART and 15% pre-HAART patients (p=0.001), while triglycerides ≥ 150 mg/dl occurred in 55.8% and 31.0% respectively, (p=0.001). Receiving of HAART was significantly and positively associated with raised total cholesterol, LDL-cholesterol, and triglycerides. The adjusted odds ratio (95% CI) of HAART-treated vs. pre-HAART was 3.80 (1.34-6.55) for total cholesterol ≥ 200 mg/dl 2.64 (1.31-5.32) for LDL- cholesterol ≥ 130 mg/dl and 2.50 (1.41-4.42) for triglycerides ≥150 mg/dl. Use of first-line antiretroviral therapy regimens that contain Efavirenz and Nevirapine were associated with raised total cholesterol, LDL-cholesterol, and triglycerides, an established atherogenic lipid profiles. Lipid profiles should be performed at baseline before commencement of antiretroviral therapy and then periodically through treatment follow-up to monitor any rising trends.
Publisher: AVES YAYINCILIK A.Ş.
Date: 16-01-2018
Publisher: Hindawi Limited
Date: 04-03-2014
DOI: 10.1155/2014/205074
Abstract: Background . Mobile phones of health professionals can harbor various potential pathogens and become exogenous sources of infection for the patients, self, and family members. This study assessed the frequency and antimicrobial susceptibility pattern of bacteria from mobile phones of health care workers. Methods . In this crosssectional study a total of 58 health care professionals mobile phones were swabbed before and after decontamination with 70% alcohol and assessed for contamination with bacteria. Bacterial isolation, identification, and antimicrobial susceptibility test was done as per the standard procedures. Results . About 98% of the mobile phones assessed in this study were contaminated with bacteria. Coagulase negative Staphylococci, S. aureus , and E. coli were the most frequently isolated bacteria. Decontamination with 70% alcohol significantly decreased the rate of contamination from 98.3% to 55.2% ( χ 2 = 30.17 P -value 0.0001 ) . About 17% of the isolates were resistant to two drugs. Conclusion . Appropriate infection prevention measures should be taken to minimize the risk that could be associated with mobile phones since the rate of contamination was high. Decontamination with 70% alcohol was effective in minimizing bacterial contamination of mobile phones so it should be used as a decontaminant agent for these apparatuses.
Publisher: Medknow
Date: 02-2015
Publisher: Springer Science and Business Media LLC
Date: 14-08-2015
Publisher: Sciencedomain International
Date: 10-01-2014
Publisher: Springer Science and Business Media LLC
Date: 15-05-2015
Publisher: Hindawi Limited
Date: 2014
DOI: 10.1155/2014/108593
Abstract: Background . Anaemia is a global public health problem which has an eminence impact on pregnant mother. The aim of this study was to assess the prevalence and predictors of maternal anemia. Method . A cross-sectional study was conducted from March 1 to April 30, 2012, on 302 pregnant women who attended antenatal care at Gondar University Hospital. Interview-based questionnaire, clinical history, and laboratory tests were used to obtain data. Bivariate and multivariate logistic regression was used to identify predictors. Result . The prevalence of anemia was 16.6%. Majority were mild type (64%) and morphologically normocytic normochromic (76%) anemia. Anemia was high at third trimester (18.9%). Low family income (AOR [95% CI] = 3.1 [1.19, 8.33]), large family size (AOR [95% CI] = 4.14 [4.13, 10.52]), hookworm infection (AOR [95% CI] = 2.72 [1.04, 7.25]), and HIV infection (AOR [95% CI] = 5.75 [2.40, 13.69]) were independent predictors of anemia. Conclusion . The prevalence of anemia was high mild type and normocytic normochromic anemia was dominant. Low income, large family size, hookworm infection, and HIV infection were associated with anemia. Hence, efforts should be made for early diagnosis and management of HIV and hookworm infection with special emphasis on those having low income and large family size.
Publisher: Medknow
Date: 08-2011
Publisher: American Society for Microbiology
Date: 10-2019
DOI: 10.1128/JVI.00202-19
Abstract: There are currently at least 71 million in iduals with chronic HCV worldwide and almost two million new infections annually. Although the advent of direct-acting antivirals (DAAs) offers highly effective therapy, considerable remaining challenges argue against reliance on DAAs for HCV elimination, including high drug cost, poorly developed health infrastructure, low screening rates, and significant reinfection rates. Accordingly, development of an effective vaccine is crucial to HCV elimination. An HCV vaccine that elicits T cell immunity in the liver will be highly protective for the following reasons: (i) T cell responses against nonstructural proteins of the virus are associated with clearance of primary infection, and (ii) long-lived liver-resident T cells alone can protect against malaria infection of hepatocytes. Thus, in this study we exploit promising vaccination platforms to highlight strategies that can be used to evoke highly functional and long-lived T cell responses in the liver for protection against HCV.
Publisher: ScopeMed
Date: 2013
Publisher: Springer Science and Business Media LLC
Date: 25-03-2014
Publisher: Informa UK Limited
Date: 02-2017
DOI: 10.2147/HIV.S125958
Publisher: MDPI AG
Date: 30-04-2019
Abstract: DNA vaccines present one of the most cost-effective platforms to develop global vaccines, which have been tested for nearly three decades in preclinical and clinical settings with some success in the clinic. However, one of the major challenges for the development of DNA vaccines is their poor immunogenicity in humans, which has led to refinements in DNA delivery, dosage in prime/boost regimens and the inclusion of adjuvants to enhance their immunogenicity. In this review, we focus on adjuvants that can enhance the immunogenicity of DNA encoded antigens and highlight the development of a novel cytolytic DNA platform encoding a truncated mouse perforin. The application of this innovative DNA technology has considerable potential in the development of effective vaccines.
Location: Ethiopia
No related grants have been discovered for Zelalem Addis Mekonnen.