Genotyping and Mutation Pattern in the Overlapping MHR Region of HBV Isolates in Southern Khorasan, Eastern Iran

Abstract

BackgroundHepatitis B virus, with 8 known distinct genotypes, is one of the most serious health problems which results to liver injuries. The surface gene of Hepatitis B virus completely overlaps with the polymerase gene. Mutations in the RT gene result in changes in the overlapping hepatitis B surface antigen.ObjectivesThe present study aimed to evaluate the genotypes and prevalence of mutations in a segment of S and RT gene in HBV isolates in Southern Khorasan, Iran.MethodsThis was a population-based study comprising 5,235 randomized samples for HBV screening. A nested-polymerase chain reaction (PCR) test was followed by direct sequencing, and the sequences blast with present sequences of NCBI database for genotyping. Alignment and phylogenic analysis was performed using MEGA-6 software, and mutation pattern of this segment was finally surveyed in Bioedit software.ResultsThe mean age was 39.07 ± 14.04 years, with 52.2% female and 47.8% male. All isolates belonged to HBV genotype D, sub-genotype D1. The most amino acid substitutions of surface protein were Q129H (34.42%) and A168V (8.2%), other escape mutants observed in this study were P127L/T, S117G, T125M, S143L, D144E and E164D. In the RT gene, Q149K was the most frequently identified amino acid substitution (9.83%), followed by L122F (8.19%), N118D/T (6.55%), L157M (4.91%), and H124Y (3.27%).ConclusionsThis finding represents an ongoing dominancy of HBV genotype D in Eastern Iran, corresponding to other parts of Iran. There were a lot of variations in the S gene leading to an escape mutation, some of which affected the corresponding area of the RT region.

Epidemiology, risk factors, and molecular characterization of occult hepatitis B infection among anti‐hepatitis B core antigen alone subjects

“…The replication cycle of HBV involves a lot of genetic instability, causing approximately 1.4 × 10 −5 to 3.2 × 10 −5 substitutions per nucleotide site. 30 Most prevalent escape mutant that observed in this study was Q129H, and in lower range I92T, T125A, and P105A, which all of them reported in previous studies as escape mutations 31 or association to OBI. 32 High rate of mutation might defect the replication cycle or producing S variants undetectable with serologic assays, and lead to incidence of OBI.…”

“…35 As S gene completely is in overlap with Pol gene, there were mutations in the corresponding region of RT, such as L80I, S85F, R110G, and L91I, which were repeatedly reported in previous studies as resistance associated. 31,36 Positions of RT at 80, 85, 91, and 110 are functional in the first domain of RT and are potentially prone to resistance in the presence of mutations. [37][38][39] Phylogenetic analysis revealed that all isolates of current study belong to genotype D, subgenotype D1, except one that was D4.…”

Interspousal Transmission of Hepatitis B virus: A Cross-Sectional Descriptive-Analytical Study

“…However, in low-endemicity areas, hepatitis B is mainly transmitted through unsafe sex and injection drug abuse during adulthood (8). Blood transfusion is also another hepatitis B transmission route (9). The most common transmission routes in Iran are maternal-infant transmission and injection drug abuse.…”

Stigmatization of Hepatitis C by Medical Sciences Students and Healthcare Providers: A Descriptive-Analytical Epidemiological Study

“…The most common and most serious types of viral hepatitis are hepatitis B and C. The prevalence of hepatitis B and C in Iran is 1.2% -5% and 0.6%, respectively (1-3). Moreover, the prevalence of hepatitis B in Birjand, Iran, is 1.6%, on average (3,4).…”