Hepatitis B genotypes and surface antigen mutants present in Pakistani blood donors

Abstract

BackgroundThe prevalence of chronic Hepatitis B Virus (HBV) infection is 2–4% in the Pakistani population, defining Pakistan as an intermediate prevalence country. In this study, hepatitis B surface antigen (HBsAg) reactive blood donations were screened using a combination of serological and molecular methods to identify immune escape HBV mutant strains and to determine the HBV genotypes and subtypes present in Pakistan.MethodsBlood donations were collected at the Armed Forces Institute of Transfusion (AFIT) located in northern Pakistan and the Hussaini Blood Bank (HBB) located in the south. From 2009 to 2013 a total of 706,575 donations were screened with 2.04% (14,409) HBsAg reactive. A total of 2055 HBsAg reactive specimens, were collected and screened using a monoclonal antibody based research assay to identify immune escape mutants followed by PCR amplification and DNA sequencing to identify the mutation present. DNA sequences obtained from 192 specimens, including mutant candidates and wild type strains, were analyzed for escape mutations, genotype, and HBsAg subtype.ResultsMutations were identified in approximately 14% of HBsAg reactive donations. Mutations at HBsAg amino acid positions 143–145 are the most common (46%) with the mutation serine 143 to leucine the most frequently occurring change (28%). While regional differences were observed, the most prevalent HBV strains are subgenotypes of D with subgenotype D1/subtype ayw2 accounting for the majority of infections; 90.2% at AFIT and 52.5% at HBB.ConclusionsThe high frequency of immune escape HBV mutants in HBV infected Pakistani blood donors highlights the need for more studies into the prevalence of escape mutants. Differences between vaccinated and unvaccinated populations, the correlation of escape mutant frequency with genotype, and impact of escape mutations in different genotype backgrounds on the performance of commercially available HBsAg assays represent avenues for further investigation.

HBV reactivation in allogeneic stem cell transplant recipients: Risk factors, outcome, and role of hepatitis B virus mutations

“…In 50% of patients, we detected known immune escape mutations, more often as minority variants but also as majority variants. Immune escape mutations have been described in the HBV genome of blood donors infected with hepatitis B with a prevalence of 14.1% (23) and in patients developing HBVr upon immunosuppression, (24) although to the best of our knowledge, not in the setting of HBVR following aHSCT. It has been postulated that immunosuppression could favor the production of mutated viral species with increased potential to evade immune responses.…”

Prevalence of occult hepatitis B in a population from the Brazilian Amazon region

“…[13][14][15] Occult hepatitis B can have clinical impacts because of the accidental transmission of infection through blood transfusions and organ transplants and the risk of HBV reactivation in immunosuppressed patients and of progression to cirrhosis and hepatocellular carcinoma. 13,16,17 Furthermore, OBI has been associated with cryptogenic hepatitis. 18,19 However, the clinical course of the disease and the mechanisms underlying the presence of HBV DNA and the absence of HBsAg in OBI are not fully understood.…”

Identification of hepatitis B virus genotype I in Thailand

“…Sequences were merged with reference sequence alignments including 29 complete HBV genotype I genomes obtained from a comprehensive alignment generated from the Genbank database on 13 February 2018 (version 1.0 alignment from Bell et al), plus eight additional published complete genome sequences in BioEdit v7.2.5 . Neighbor‐joining HBV phylogenetic trees were generated as previously described, and trees were visualized using FigTree software (version 1.4.2; A. Rambaut, Institute of Evolutionary Biology, University of Edinburgh, Scotland). HBV‐I strains branching closely with other references were removed to generate a simpler tree for visualization in Figure B.…”

“…Subgenomic sequences were generated for the surface antigen/reverse transcriptase (SRT) region as previously described. 26 The HBV-I genome was amplified in two overlapping fragments using Adventage-2 polymerase reagents (Clontech, Palo Alto, CA). Primer pairs for the S-core fragment were HBV-238F ( 14,15,18 in BioEdit v7.2.5.…”

“…Primer pairs for the S-core fragment were HBV-238F ( 14,15,18 in BioEdit v7.2.5. 27 Neighbor-joining HBV phylogenetic trees were generated as previously described, 26…”