Genetic Diversity of Hepatitis B Virus Genomes Isolated from Patients Attending Health Facilities in HBV-Endemic Regions in Kenya

Background: Hepatitis B virus (HBV) is the smallest partially double-stranded, reverse-transcribing DNA virus, with four open reading frames (ORFs) encoding viral proteins. It is classified into nine geographically distributed genotypes (A–I). In Kenya, the molecular characterization of HBV among patients seeking medical care remains poorly defined. Objectives: This observational study aimed to characterize HBV among patients seeking medical care in the endemic region of Kenya, focusing on circulating genotypes and ORF mutations. Methodology: Serum samples were collected from the outpatient departments of selected health facilities, with demographic and clinical information extracted from patients’ medical records. Hepatitis B surface antigen (HBsAg) was tested at the facilities, and a total of 85 HBsAg-positive samples were collected for molecular analysis. The basal Core promoter and pre-core (BCP/PC), polymerase, and surface regions of the viral genome were amplified and sequenced to determine genotypes and to profile their mutations. Results: Out of 85 HBsAg-positive samples, 38 samples tested positive for HBV DNA, and 26 samples were successfully sequenced. HBV genotype A was prevalent 73.1% (19/26), followed by genotype D 23.1% (6/26), and genotype E 3.8% (1/26). Genotype A sequences clustered with both A1 Asian and African subgenotypes, whereas genotype D clustered with subgenotypes D6 and D1. All HBV genotype A, D, and E sequences were serotypes adw2, ayw2, and ayw4, respectively. HBV core promoter mutations (A1762T/G1764A) were detected in both genotype D and genotype A isolates. The pre-core G1896A mutation was highly prevalent in genotype D samples (5/6; 83.3%) but was not observed in genotypes A or E. Analysis of mutations within the aa determinant region revealed genotype-specific patterns: genotype A predominantly harbored V14A, P46H, S58C, and P67Q substitutions; genotype E showed N59S; and genotype D exhibited V14A, C69stop, S104T, and W182stop mutations. Two drug resistance mutations (V191I and A194T) were present in two chronic patients, one with genotype A and the other with genotype D. Conclusion: HBV genotypes A and D are the most prevalent among Kenyan patients with chronic HBV infection. The presence of point mutations in the ORFs among patients seeking medical care highlights the need for a molecular surveillance to better understand the viral diversity and its potential clinical and public health implications.