Phylogenetic analysis of Hepatitis B virus in Pakistan

Objective: To identify the distribution pattern of Hepatitis B Virus (HBV) genotype in a group of patients and to study its phylogenetic divergence. Study Design: An observational study. Place and Duration of Study: The clinics of Gastroenterology Unit, Ziauddin University, from January to December 2006. Methodology: Two hundred and one HBV infected patients were genotyped for this study. All HbsAg positive individuals, either healthy carriers or suffering from conditions such as acute or chronic hepatitis, cirrhosis and hepatocellular carcinoma were included. Hepatitis B patients co-infected with other hepatic viruses were excluded. Hepatitis B virus DNA was extracted from serum, and subjected to a nested PCR, using the primers type-specific for genotype detection. Phylogenetic analysis was performed in the pre-S1 through S genes of HBV. The divergence was studied through 15 sequences of 967bp submitted to the DBJ/EMBL/GenBank databases accessible under accession number EF584640 through EF584654. Results: Out of 201 patients tested, 156 were males and 45 were females. Genotype D was the predominant type found in 128 (64%) patients followed by A in 47 (23%) and mixed A/D in 26 (13%). Phylogenetic analysis confirmed the dominance of genotype D and subtype ayw2. Conclusion: There was dominance of genotype D subtype ayw2. It had a close resemblance with HBV strains that circulate in Iran, India and Japan.