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Sobajo OA, Oguzie JU, Adegboyega B, Eromon P, Happi C, Komolafe I, Folarin O. Detection of Immune Escape and Basal Core Promoter/Precore Gene Mutations in Hepatitis B Virus Isolated from Asymptomatic Hospital Attendees in Two Southwestern States in Nigeria. Viruses 2023; 15:2188. [PMID: 38005866 PMCID: PMC10674980 DOI: 10.3390/v15112188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 10/22/2023] [Accepted: 10/29/2023] [Indexed: 11/26/2023] Open
Abstract
Several mutations in the surface (S), basal core promoter (BCP), and precore (PC) genes of the hepatitis B virus have been linked to inaccurate diagnosis and the development of immune escape mutants (IEMs) of the infection, which can lead to chronic infection. Understanding the prevalence and spread of these mutations is critical in the global effort to eliminate HBV. Blood samples were collected from 410 people in Osun and Ekiti states, southwest Nigeria, between 2019 and 2021. Participants were drawn from a group of asymptomatic people who were either blood donors, outpatients, or antenatal patients with no record of HBV infection at the medical outpatients' unit of the hospital. DNA was extracted from plasma using a Qiagen DNEasy kit, followed by nested PCR targeting HBV S and BCP/PC genes. The Sanger sequencing method was used to sequence the positive PCR amplicons, which were further analyzed for IEMs, BCP, and PC mutations. HBV-DNA was detected in 12.4% (51/410) of individuals. After DNA amplification and purification, 47.1% (24) of the S gene and 76.5% (39) of the BCP/PC gene amplicons were successfully sequenced. Phylogenetic analysis showed that all the HBV sequences obtained in this study were classified as HBV genotype E. Mutational analysis of the major hydrophilic region (MHR) and a-determinant domain of S gene sequences revealed the presence of three immune escape mutations: two samples harbored a T116N substitution, six samples had heterogenous D144A/N/S/H substitution, and one sample had a G145E substitution, respectively. The BCP/PC region analysis revealed a preponderance of major BCP mutants, with the prevalence of BCP double substitutions ranging from 38.5% (A1762T) to 43.6% (G1764A). Previously reported classical PC mutant variants were observed in high proportion, including G1896A (33.3%) and G1899A (12.8%) mutations. This study confirms the strong presence of HBV genotype E in Nigeria, the ongoing circulation of HBV IEMs, and a high prevalence of BCP/PC mutants in the cohorts. This has implications for diagnosis and vaccine efficacy for efficient management and control of HBV in the country.
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Affiliation(s)
- Oguntope Adeorike Sobajo
- Department of Biological Sciences, Faculty of Natural Sciences, Redeemer’s University, Ede 232102, Osun State, Nigeria or (O.A.S.); (J.U.O.); (C.H.); (I.K.)
- African Centre of Excellence for Genomics of Infectious Diseases, Redeemer’s University, Ede 232102, Osun State, Nigeria; (B.A.); (P.E.)
- Department of Biological Science, College of Sciences, Afe Babalola University, Ado-Ekiti 360101, Ekiti State, Nigeria
| | - Judith Uche Oguzie
- Department of Biological Sciences, Faculty of Natural Sciences, Redeemer’s University, Ede 232102, Osun State, Nigeria or (O.A.S.); (J.U.O.); (C.H.); (I.K.)
- African Centre of Excellence for Genomics of Infectious Diseases, Redeemer’s University, Ede 232102, Osun State, Nigeria; (B.A.); (P.E.)
| | - Benjamin Adegboyega
- African Centre of Excellence for Genomics of Infectious Diseases, Redeemer’s University, Ede 232102, Osun State, Nigeria; (B.A.); (P.E.)
| | - Philomena Eromon
- African Centre of Excellence for Genomics of Infectious Diseases, Redeemer’s University, Ede 232102, Osun State, Nigeria; (B.A.); (P.E.)
| | - Christian Happi
- Department of Biological Sciences, Faculty of Natural Sciences, Redeemer’s University, Ede 232102, Osun State, Nigeria or (O.A.S.); (J.U.O.); (C.H.); (I.K.)
- African Centre of Excellence for Genomics of Infectious Diseases, Redeemer’s University, Ede 232102, Osun State, Nigeria; (B.A.); (P.E.)
| | - Isaac Komolafe
- Department of Biological Sciences, Faculty of Natural Sciences, Redeemer’s University, Ede 232102, Osun State, Nigeria or (O.A.S.); (J.U.O.); (C.H.); (I.K.)
| | - Onikepe Folarin
- Department of Biological Sciences, Faculty of Natural Sciences, Redeemer’s University, Ede 232102, Osun State, Nigeria or (O.A.S.); (J.U.O.); (C.H.); (I.K.)
- African Centre of Excellence for Genomics of Infectious Diseases, Redeemer’s University, Ede 232102, Osun State, Nigeria; (B.A.); (P.E.)
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Dagnew M, Moges F, Tiruneh M, Million Y, Gelaw A, Adefris M, Belyhun Y, Liebert UG, Maier M. Molecular diversity of hepatitis B virus among pregnant women in Amhara National Regional State, Ethiopia. PLoS One 2022; 17:e0276687. [PMID: 36378635 PMCID: PMC9665361 DOI: 10.1371/journal.pone.0276687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 10/11/2022] [Indexed: 11/17/2022] Open
Abstract
Background Despite the availability of effective vaccines and treatments for hepatitis B virus (HBV), it continues to be a major public health problem in sub-Saharan Africa including Ethiopia. Routine screening for HBV in pregnant women is widely recommended, but there is lack of screening for HBV during pregnancy in Ethiopia. Therefore, this study aimed to assess viral load, and genetic diversity among pregnant women in the Amhara National Regional State, Ethiopia. Materials and methods Hepatitis B surface antigen (HBsAg) testing was performed on 1846 pregnant women, 85 of who tested positive were included in this study. HBV DNA was isolated from 85 positive sera, and the partial surface/polymerase gene was amplified and sequenced. HBV genotypes, sub-genotypes, serotypes and mutations in surface genes and polymerase were studied. Results Out of 85 pregnant women`s HBsAg positive sera, 59(69.4%) had detectable viral DNA. The median viral load was 3.4 log IU/ml ranging from 2.6 to7.6 and 46 samples were successfully sequenced and genotyped. Genotypes A and D were identified in 39 (84.8%) and 7 (15.2%); respectively. All genotype A isolates were further classified into sub-genotype A1 and serotype adw2 (84.8%) whereas genotype D isolates were further classified into three sub genotypes; 2 (4.3%) D2, 1(2.2%) D4, and 4 (8.7%) D10 with serotypes ayw2 (10.9%), and ayw3 (4.3%). There were 19 (41.3%) surface gene mutations in the major hydrophilic region (MHR). Six (13.1%) of them were discovered in MHR`s `a’-determinant region. Six polymerase gene mutations (13%) were identified. Conclusion Genotype A was the predominant genotype in the Amhara National Regional State. The surface and polymerase gene mutations identified in this study may lead to immune therapy failure, diagnostics escape and drug resistance. Thus, the data generated in this study will contribute to the planning of HBV diagnosis, vaccination and treatment, and most importantly to the prevention of vertical transmission of HBV in Ethiopia. Therefore, further molecular studies on HBV are warranted and continuous surveillance is important for patient management and for the prevention and control of HBV infection in the country.
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Affiliation(s)
- Mulat Dagnew
- Department of Medical Microbiology, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
- Department of Virology, Institute of Medical Microbiology and Virology, Leipzig University, Leipzig, Germany
- * E-mail:
| | - Feleke Moges
- Department of Medical Microbiology, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Moges Tiruneh
- Department of Medical Microbiology, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Yihenew Million
- Department of Medical Microbiology, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Aschalew Gelaw
- Department of Medical Microbiology, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Mulat Adefris
- Department of Gynecology and Obstetrics, School of Medicine, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Yeshambel Belyhun
- Department of Medical Microbiology, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
- Department of Virology, Institute of Medical Microbiology and Virology, Leipzig University, Leipzig, Germany
| | - Uwe G. Liebert
- Department of Virology, Institute of Medical Microbiology and Virology, Leipzig University, Leipzig, Germany
| | - Melanie Maier
- Department of Virology, Institute of Medical Microbiology and Virology, Leipzig University, Leipzig, Germany
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Belyhun Y, Liebert UG, Maier M. Molecular epidemiology of hepatitis B virus among HIV co-infected and mono-infected cohorts in Northwest Ethiopia. Virol J 2022; 19:53. [PMID: 35331278 PMCID: PMC8944073 DOI: 10.1186/s12985-022-01774-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 03/02/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Hepatitis B virus (HBV) infection is a particular concern in human immunodeficiency virus (HIV) infected individuals. In Ethiopia, detailed clinical and virological descriptions of HBV prevailing during HIV co-infection and symptomatic liver disease patients are lacking. The aim of this study was to investigate HBV virological characteristics from Ethiopian HBV/HIV co-infected and HBV mono-infected individuals. METHODS A total of 4105 sera from HIV positive individuals, liver disease patients, and blood donors were screened serologically for HBV. The overlapping polymerase/surface genome region of HBV from 180 infected individuals was extracted, amplified, and sequenced for genotypic analysis. RESULTS The HBsAg seroprevalence was detected 43% in liver disease patients, 8.4% in blood donors, and 6.7% in HIV/HBV co-infected individuals. The occult HBV prevalence was 3.7% in HIV/HBV co-infected individuals and 2.8% in blood donors with an overall prevalence rate of 3.4%. A phylogenetic analysis showed three HBV genotypes; A (61.1%), D (38.3%) and E (0.6%). Genotype A belongs to subtypes A1 (99.1%) and A9 (0.9%), but genotype D showed heterogeneous subtypes; D2 (63.8%) followed by D4 (21.7%), D1 (8.7%), D3 (4.3%), and D10 (1.4%). CONCLUSIONS The HIV/HBV co-infected individuals and blood donors showed lower HBsAg seroprevalence compared to liver diseases patients. Occult HBV prevalence showed no difference between HIV/HBV co-infected and blood donor groups. This study demonstrated predominance distribution of HBV subtypes A1 and D2 in northwest Ethiopia. The observed virological characteristics could contribute for evidence-based management of viral hepatitis in Ethiopia where antiretroviral therapy guidelines do not cater for viral hepatitis screening during HIV co-infection.
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Affiliation(s)
- Yeshambel Belyhun
- Department of Virology, Institute of Medical Microbiology, Leipzig University, Leipzig, Germany. .,School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia.
| | - Uwe Gerd Liebert
- Department of Virology, Institute of Medical Microbiology, Leipzig University, Leipzig, Germany
| | - Melanie Maier
- Department of Virology, Institute of Medical Microbiology, Leipzig University, Leipzig, Germany
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Mbamalu C, Ekejindu I, Enweani I, Kalu S, Igwe D, Akaeze G. Hepatitis B virus precore/core region mutations and genotypes among hepatitis B virus chronic carriers in South-Eastern, Nigeria. Int J Health Sci (Qassim) 2021; 15:26-38. [PMID: 33708042 PMCID: PMC7934135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
OBJECTIVES The study aimed at detecting the prevailing hepatitis B virus (HBV) genotypes and the presence of clinically relevant mutations in the precore/core gene of the HBV DNA, among patients with chronic infection in South-eastern, Nigeria. METHODS A total of 72 participants with chronic HBV infection were enrolled into the study. Plasma samples from those with detectable HBV DNA were subjected to nested Polymerase Chain Reaction amplification using the precore/core specific primers. This resulted to the successful amplification and sequencing of the HBV precore/core region DNA from 16 participants. Mutation analysis on the precore/core region detected the presence of certain HBV precore/core gene mutations. Genotyping was carried out by phylogenetic analysis. RESULTS The precore region mutation at nucleotide position 1896, which is a G to A change resulting to a nonsense mutation, was detected in 6.25% of the participants. Other HBV precore region mutations that were detected include: G1899A, T1846A, G1862C, G1888A, T1821C, C1826T, A1827C, A1850T, C1858T, precore start codon Kozak sequence mutations and some novel core region mutations such as G/A1951T and G1957A. Genotyping revealed the existence of HBV genotype/subgenotype A1 (87.5%) and D (12.5%) among the participants. There was no significant difference in the occurrence of specific precore/core mutations among the HBV/hepatitis C virus dually infected and HBV mono-infected participants. CONCLUSION The data suggest the likelihood of a more severe outcome of hepatitis caused by HBV in South-eastern Nigeria due to the occurrence of a variety of precore/core mutation, which resulted to HBeAg-negative chronic HBV infection among the participants.
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Affiliation(s)
- Chinenye Mbamalu
- Medical Laboratory Services, Alex Ekwueme Federal University Teaching Hospital, Abakaliki, Ebonyi State, Nigeria,Address for correspondence: Chinenye Mbamalu, Medical Laboratory Services, Alex Ekwueme Federal University Teaching Hospital, Abakaliki, Ebonyi State, Nigeria. Telephone: +2348068993161. E-mail:
| | - Ifeoma Ekejindu
- Department of Medical Laboratory Science, Faculty of Health Sciences and Technology, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria
| | - Ifeoma Enweani
- Department of Medical Laboratory Science, Faculty of Health Sciences and Technology, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria
| | - Stephen Kalu
- Department of HIV Care, PCR Laboratory Unit, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Anambra State, Nigeria
| | - David Igwe
- Department of Biotechnology, Ebonyi State University, Abakaliki, Ebonyi State, Nigeria,Department of Plant Pathology and Plant-Microbe Biology/Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York, USA
| | - Gloria Akaeze
- Department of HIV Care, PCR Laboratory Unit, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Anambra State, Nigeria
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Peiffer KH, Spengler C, Basic M, Jiang B, Kuhnhenn L, Obermann W, Zahn T, Glitscher M, Loglio A, Facchetti F, Carra G, Kubesch A, Vermehren J, Knop V, Graf C, Dietz J, Finkelmeier F, Herrmann E, Trebicka J, Grünweller A, Zeuzem S, Sarrazin C, Lampertico P, Hildt E. Quadruple mutation GCAC1809-1812TTCT acts as a biomarker in healthy European HBV carriers. JCI Insight 2020; 5:135833. [PMID: 33055418 PMCID: PMC7710305 DOI: 10.1172/jci.insight.135833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 10/07/2020] [Indexed: 12/14/2022] Open
Abstract
Many mutation analyses of the HBV genome have been performed in the search for new prognostic markers. However, the Kozak sequence preceding precore was covered only infrequently in these analyses. In this study, the HBV core promoter/precore region was sequenced in serum samples from European inactive HBV carriers. Quadruple mutation GCAC1809-1812TTCT was found with a high prevalence of 42% in the Kozak sequence preceding precore among all HBV genotypes. GCAC1809-1812TTCT was strongly associated with coexistence of basal core promoter (BCP) double mutation A1762T/G1764A and lower HBV DNA levels. In vitro GCAC1809-1812TTCT lead to drastically diminished synthesis of pregenomic RNA (pgRNA), precore mRNA, core, HBsAg, and HBeAg. Calculation of the pgRNA secondary structure suggests a destabilization of the pgRNA structure by A1762T/G1764A that was compensated by GCAC1809-1812TTCT. In 125 patients with HBV-related cirrhosis, GCAC1809-1812TTCT was not detected. While a strong association of GCAC1809-1812TTCT with inactive carrier status was observed, BCP double mutation was strongly correlated with cirrhosis, but this was only observed in absence of GCAC1809-1812TTCT. In conclusion, our data reveal that GCAC1809-1812TTCT is highly prevalent in inactive carriers and acts as a compensatory mutation for BCP double mutation. GCAC1809-1812TTCT seems to be a biomarker of good prognosis in HBV infection. HBV core promoter/precore region was sequenced in serum samples of European inactive HBV carriers, revealing that GCAC1809-1812TTCT mutation is highly prevalent in inactive carriers.
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Affiliation(s)
- Kai-Henrik Peiffer
- Department of Gastroenterology and Hepatology, University Hospital Frankfurt, Frankfurt, Germany.,Paul Ehrlich Institute, Division of Virology, Langen, Germany
| | | | - Michael Basic
- Department of Gastroenterology and Hepatology, University Hospital Frankfurt, Frankfurt, Germany.,Paul Ehrlich Institute, Division of Virology, Langen, Germany
| | - Bingfu Jiang
- Paul Ehrlich Institute, Division of Virology, Langen, Germany
| | - Lisa Kuhnhenn
- Department of Gastroenterology and Hepatology, University Hospital Frankfurt, Frankfurt, Germany
| | - Wiebke Obermann
- Institute of Pharmaceutical Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Tobias Zahn
- Paul Ehrlich Institute, Division of Virology, Langen, Germany
| | - Mirco Glitscher
- Paul Ehrlich Institute, Division of Virology, Langen, Germany
| | - Alessandro Loglio
- A.M. and A. Migliavacca Center for Liver Disease, Division of Gastroenterology and Hepatology, Fondazione IRCCS Cà Granda Maggiore Hospital, University of Milan, Milan, Italy
| | - Floriana Facchetti
- A.M. and A. Migliavacca Center for Liver Disease, Division of Gastroenterology and Hepatology, Fondazione IRCCS Cà Granda Maggiore Hospital, University of Milan, Milan, Italy
| | - Gert Carra
- Paul Ehrlich Institute, Division of Virology, Langen, Germany
| | - Alica Kubesch
- Department of Gastroenterology and Hepatology, University Hospital Frankfurt, Frankfurt, Germany
| | - Johannes Vermehren
- Department of Gastroenterology and Hepatology, University Hospital Frankfurt, Frankfurt, Germany
| | - Viola Knop
- Department of Gastroenterology and Hepatology, University Hospital Frankfurt, Frankfurt, Germany
| | - Christiana Graf
- Department of Gastroenterology and Hepatology, University Hospital Frankfurt, Frankfurt, Germany
| | - Julia Dietz
- Department of Gastroenterology and Hepatology, University Hospital Frankfurt, Frankfurt, Germany
| | - Fabian Finkelmeier
- Department of Gastroenterology and Hepatology, University Hospital Frankfurt, Frankfurt, Germany
| | - Eva Herrmann
- Department of Medicine, Institute of Biostatistics and Mathematical Modeling, J.W. Goethe University, Frankfurt, Germany
| | - Jonel Trebicka
- Department of Gastroenterology and Hepatology, University Hospital Frankfurt, Frankfurt, Germany
| | - Arnold Grünweller
- Institute of Pharmaceutical Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Stefan Zeuzem
- Department of Gastroenterology and Hepatology, University Hospital Frankfurt, Frankfurt, Germany
| | - Christoph Sarrazin
- Department of Gastroenterology and Hepatology, University Hospital Frankfurt, Frankfurt, Germany.,Department of Gastroenterology, St. Josefs Hospital, Wiesbaden, Germany
| | - Pietro Lampertico
- A.M. and A. Migliavacca Center for Liver Disease, Division of Gastroenterology and Hepatology, Fondazione IRCCS Cà Granda Maggiore Hospital, University of Milan, Milan, Italy
| | - Eberhard Hildt
- Paul Ehrlich Institute, Division of Virology, Langen, Germany.,German Center for Infection Research (DZIF), Gießen-Marburg-Langen, Germany
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Koyaweda GW, Ongus JR, Machuka E, Juma J, Macharia R, Komas NP, Pelle R. Detection of circulating hepatitis B virus immune escape and polymerase mutants among HBV-positive patients attending Institut Pasteur de Bangui, Central African Republic. Int J Infect Dis 2019; 90:138-144. [PMID: 31682960 PMCID: PMC6912157 DOI: 10.1016/j.ijid.2019.10.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 10/25/2019] [Accepted: 10/27/2019] [Indexed: 02/06/2023] Open
Abstract
Background Previous studies in the Central African Republic (CAR) have reported the presence of hepatitis B virus (HBV) recombinant genotype E/D and a suspicion of immune escape mutants (IEMs), without further investigation into their impact on prevention and diagnosis. Consequently, this study investigated HBV mutations among hepatitis B surface antigen (HBsAg)-positive patients attending Institut Pasteur de Bangui in the CAR. Methods Sera from a total of 118 HBsAg-positive patients with no previous history of HBV treatment or vaccination at the Institut Pasteur de Bangui, were sampled between 2017 and 2019. Subsequently, the region spanning the surface and polymerase genes of HBV was amplified by PCR and sequenced. HBV sequences were genotyped/subgenotyped by phylogenetic analysis and serotyped based on predicted amino acid residues at positions s122, s127, s140, s159, and s160. They were then analyzed for HBV IEMs and polymerase mutations. Results The region spanning the surface and polymerase genes was successfully amplified and sequenced for 51 samples. Of the HBV sequences, 49 were genotype E and two were genotype A subgenotype A1; these were serotyped as ayw4 and ayw1, respectively. Potential IEMs sY100C, sA128V, and sM133T, and several polymerase mutants were identified. Conclusions This study raises awareness of the need for further studies to be conducted on a large scale to better understand HBV mutations for improved disease control and prevention strategies in the country.
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Affiliation(s)
| | - Juliette Rose Ongus
- Jomo Kenyatta University of Agriculture and Technology, Medical Laboratory Sciences Department, Nairobi, Kenya
| | - Eunice Machuka
- Biosciences eastern and central Africa International Livestock Research Institute (BecA-ILRI) Hub, Nairobi, Kenya
| | - John Juma
- Biosciences eastern and central Africa International Livestock Research Institute (BecA-ILRI) Hub, Nairobi, Kenya
| | - Rosaline Macharia
- Center for Biotechnology and Bioinformatics, University of Nairobi, Nairobi, Kenya
| | - Narcisse Patrice Komas
- Institut Pasteur de Bangui, Viral Hepatitis Laboratory, Bangui, Central African Republic
| | - Roger Pelle
- Jomo Kenyatta University of Agriculture and Technology, Medical Laboratory Sciences Department, Nairobi, Kenya.
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