A study of genotypes, mutants and nucleotide sequence of hepatitis B virus 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.