Molecular characterization of hepatitis B virus in Vietnam

Abstract

Background: Hepatitis B virus (HBV) infection is a major public health problem globally. HBV genotypes and subgenotypes influence disease transmission, progression, and treatment outcome. A study was conducted among treatment naive chronic HBV patients in southern Vietnam to determine the genotypes and subgenotypes of HBV. Methods: A prospective, exploratory study was conducted among treatment naïve chronic HBV patients attending at the Hospital for Tropical Diseases, in Ho Chi Minh City, Vietnam during 2012, 2014 and 2016. HBV DNA positive samples (systematically selected 2% of all treatment naïve chronic patients during 2012 and 2014, and 8% of all treatment naïve chronic patients during 2016) were subjected to whole genome sequencing (WGS) either by Sanger or Illumina sequencing. WGS was used to define genotype, sub-genotype, recombination, and the prevalence of drug resistance and virulence-associated mutations. Results: One hundred thirty five treatment naïve chronic HBV patients including 18 from 2012, 24 from 2014, and 93 from 2016 were enrolled. Of 135 sequenced viruses, 72.6% and 27.4% were genotypes B and C respectively. Among genotype B isolates, 87.8% and 12.2% were subgenotypes B4 and B2 respectively. A G1896A mutation in the precore gene was present in 30.6% of genotype B isolates. The genotype C isolates were all subgenotype C1 and 78.4% (29/37) of them had at least one basal core promoter (BCP) mutation. A1762T and G1764 T mutations and a double mutation (A1762T and G1764 T) in the BCP region were significantly more frequent in genotype C1 isolates (p < 0.001). Conclusion: HBV genotype B including subgenotype B4 is predominant in southern Vietnam. However, one fourth of the chronic HBV infections were caused by subgenotype C1.

Prevalence of Hepatitis B Virus and Hepatitis C Virus Infections among Beauticians in Quy Nhon City, Binh Dinh Province, Vietnam

“…31 Our result was similar to previous studies conducted in Vietnam that indicated that HBV genotype B was the most prevalent (63.0%-72.6%) followed by genotype C (18.0%-28.0%). [32][33][34][35] Like other studies, 5,6,23,24,28,36 our results also showed no statistically significant association between possible occupational risk factors for HBV infection among beauticians. However, some studies have suggested that beauticians are a high-risk group for HBV and HCV infections based on the statistically significant difference in prevalence among case and control groups, 24,36,37 or by comparing HBV infected cases with HAV infected cases as a control group.…”

Insights From Deep Sequencing of the HBV Genome—Unique, Tiny, and Misunderstood

“…Based on the EcoRI numbering convention, breakages tend to occur at sites within nucleotides 1700–2000 and 2100–2300, 83 possibly because of the decreased between-genotype diversity observed in these regions. In addition to the genotype I recombinant, examples include B and C recombinants in parts of mainland East Asia that are now defined as sub-genotypes B2, 22 , 84 B3, 85 and B4 85 ; C and D recombinants reported from Tibet 83 and China84, 86; D and E recombinants reported from different parts of Africa87, 88; A, C, and G recombinants reported in 2 patients in China—although this is based on sequencing only a 1-kb stretch of the genome 89 ; and A and G recombinant sequences identified in a patient with A2 infection 90 and in several patients in Canada 91 …”

“…HBV sequence data largely consist of consensus sequences of individual viral genes derived by Sanger sequencing. However, next-generation sequencing (NGS) platforms are rapidly becoming more accessible and affordable, in addition to new bioinformatic approaches to handle the resulting datasets 21, 22, 23. In addition to enabling whole-genome sequencing, NGS offers a powerful method for detection of minor variants relevant to the identification of drug resistance,24, 25, 26 studies of quasispecies dynamics, 27 and characterization of complex viral populations 28 .…”

Existence of Hepatitis B Surface Protein Mutations and Other Variants: Demand for Hepatitis B Infection Control in Cambodia

“…The genome sequences revealed the genotype distribution pattern of HBV in the whole Cambodia. where HBV genotype B is predominant (72.6%); particularly sub-genotype B4 (87.8%) [27]. HBV genotype C was abundantly found in the Stung Treng, Ratanakiri and Preah Vihear provinces, the northeast part of Cambodia and border region to Laos, where HBV genotype C (55.4%) is also predominant [28].…”