Prevalence of Hepatitis B virus genotype D in females in Karachi, Pakistan.

BACKGROUND Hepatitis B virus (HBV) is an etiological agent of acute and chronic liver disease existing throughout the world. The high genetic variability of HBV genome is reflected by eight genotypes (A to H), and each genotype has characteristic geographical distribution, which is important epidemiologically. Previous studies from the province of Sindh, Pakistan, have reported that genotypes A and D as prevalent HBV genotypes. The aim of the study was to investigate the prevalence of HBV genotypes in physically healthy females at two universities in Karachi, Sindh, Pakistan. METHODOLOGY Blood was collected from a total of 4,000 healthy female volunteer students and serum samples obtained were screened for Hepatitis B surface antigen (HBsAg), and anti-HBs antibodies by immunochromatography and ELISA. Genotyping was conducted for 6 HBV genotypes (A through F). Both genotyping and sequencing data of HBV positive females are described. RESULTS Out of 4,000 volunteers, 180 (4.5%) tested positive for HBsAg and 20 (0.5%) were positive for HBs antibodies. All 180 serum samples were genotyped by PCR and sequencing analyses was conducted for 21 samples. Out of 180 HBsAg positive samples, 150 showed a single HBV D genotype infection; 29 showed co-infection of genotypes B and D; and 1 exhibited co-infection of genotypes C and D. Twenty-one representative samples were selected randomly from genotypes B, D, and C for sequencing and each isolate clustered with respective reference genotype sequence, thus validating the genotyping strategy. CONCLUSION Genotype D appears to be the dominant genotype prevalent in Karachi's otherwise healthy female population.