Complete Genome Sequencing of Occult Hepatitis B Virus in Hemodialysis Patients Reveals Subgenotype D2 and Immune Escape Mutations in Bangladesh.
Hepatitis B virus (HBV) remains a major global health concern, and occult HBV infection (OBI) presents significant diagnostic and clinical challenges, particularly among hemodialysis (HD) patients. This study is aimed at characterizing complete HBV genomes from maintenance HD patients with OBI in Bangladesh to elucidate genetic features, mutational patterns, and clinical implications. Serum samples from two HBsAg-negative HD patients were screened by ELISA and quantitative PCR. Viral DNA was amplified by PCR across four overlapping open reading frames (ORFs) and sequenced on the Illumina platform. Genome assembly, phylogenetic analysis, and mutational profiling were performed using reference datasets and bioinformatics tools. Antigenicity and hydrophilicity of HBsAg were predicted in silico. Both patients were anti-HBc and anti-HBs positive with high HBV DNA loads (2.29 × 1010 and 2.53 × 1010 copies/mL). Full-length genomes (3182 bp) were successfully sequenced and phylogenetic analysis showed both HBV genomes clustered within Genotype D, Subgenotype D2, and subtype ayw3, consistent with previously reported Bangladeshi HBV genomes. Comparative mutational analysis identified substitutions such as T1753C in the basal core promoter, C1845T in preC, and D144E within the "a" determinant of HBsAg, suggesting potential roles in vaccine escape, immune escape, and diagnostic failure. Several nonsynonymous mutations were also detected in polymerase, though none were potentially associated with antiviral resistance. Antigenicity and hydrophilicity profiles of HBsAg and its major hydrophilic region remained largely conserved. These findings demonstrate the persistence of OBI in HD patients and provide an initial indication of the need for genomic surveillance to monitor immune-escape mutations and improve HBV diagnostic strategies in endemic regions.