A study of genotypes, mutants and nucleotide sequence of hepatitis B virus in Pakistan: HBV genotypes in pakistan

BACKGROUND: Hepatitis B virus (HBV) genotypes and mutations are gaining importance in determining the clinical course of chronic liver disease. OBJECTIVES: To determine and compare the distribution of HBV genotypes and genomic variations in Pakistan to other parts of the world. PATIENTS AND METHODS: We conducted a prospective study at Aga Khan University Hospital from December 2006 to December 2008. HBV genotype was determined in 257 HBV DNA-positive patients. Patients were divided into two groups according to HBeAg positivity. Mutations in the pre-core and core promoter regions of HBV were determined in HBeAg-negative patients by line probe INNOLIPA assay. RESULTS: The mean±SD age of patients was 28±5 years; there were 201 (78%) men. HBeAg was positive in 219 (85%) patients and negative in 38 (15%). HBeAg-positive patients were younger than HBeAg-negative patients (95% vs 21% in ≤30 years, p<0.001). HBV genotype D found in 247 (96.2 %) patients followed by a combined infection with HBV genotype B+D in 9 (3.3%) and 1 (0.5%) with genotype A. The mutations identified in 38 HBeAg-negative patients were T1762/A1764 in 21 (55.2%), PC mutant in 7 (18.4%), T1762/A1764/PC mutant in 2 (5%) and T1762/A1764/PC wild mutation in 1 (2%); no mutation identified in 7 (18.4%). Phylogenetic analysis did not show any significant differences between HBV genotype D isolated from Pakistan and those isolated from other parts of the world. CONCLUSIONS: HBV genotype D is predominant in Pakistan, irrespective of HBeAg status. PC and BCP mutations were found in significant numbers of patients infected with genotype D. The HBV genotype D isolates from Pakistan are identical to the sequences isolated from other parts of the world.