Distribution of hepatitis B virus genotypes and demography in the general population of Karachi, Sindh.

Hepatitis B is a major global burden, with 253 million infected people. There are at least ten Hepatitis B virus (HBV) genotypes and 35 subgenotypes, with distinct ethno-geographical distributions and manifest differences in their biological characteristics, display close association with clinical outcomes, severity of disease, and response to antiviral therapy. The aim of the study was to identify the predominant circulating genotypes of HBV in the population of Karachi, Sindh. A demographic assessment was conducted alongside a serological evaluation of markers specifically HBsAg, HBsAb, HBeAb, and HBcAb to determine the clinical infection profile of the study cohort. An initial molecular identification was performed by first round of PCR via specific primers P1 and S1-2 for PreS1/S2 gene. The HBV genotypes (A to F) was determined by nested PCR using primer pairs for the conserved sequence of HBV pre-S gene and S gene, and subsequently validated by phylogenetic analysis. The study findings indicated that the mean age of the study participants was 33.94 years, with a median age of 31.5 years. The percentage of HBV positive female and male were 51.5% and 48.5%, respectively. The results of this pilot study indicated that the probable predominant genotype circulating in Karachi is D, followed by B and C. Mixed infection of B, C, and D was also observed. Almost all the D positive samples were positive for HBsAg.