Hepatitis A viral genotypes and clinical relevance: Clinical and molecular characterization of hepatitis A virus isolates from northern India

Viral hepatitis caused by hepatitis A virus (HAV) infection is a worldwide disease; in most cases, it causes an acute self-limited illness. The nucleotide sequence analysis of HAV has classified the virus in seven different genotypes, which include human (I-III and VII) and simian (IV-VI) groups. Most human strains belong to the genotype I, which has been divided into sub-genotypes IA and IB. The present study has been carried out to determine the prevalence of HAV genotypes from northern India and to correlate with their clinical characteristics. Peripheral venous blood collected from 546 cases of acute viral hepatitis was employed for enzyme-linked immunosorbent assays (ELISA) for the serological detection of hepatitis A-C and E viruses. A nested reverse transcription RT-PCR was performed to detect HAV genome, and the positive samples were sequenced to determine the HAV genotypes. Of 73 (13.4%) cases positive for IgM anti-HAV, 29 (39.7%) were positive for HAV RNA. Genotyping was done for 27 (93%) positive cases by direct nucleotide sequencing. Phylogenetic analysis revealed that 15 (55.6%) isolates belonged to genotype 1A, while 12 (44.4%) isolates to IIIA genotype. The results suggest that both genotypes IA and IIIA are almost equally prevalent in northern India. A significant difference was observed with respect to the mean liver-function profile between the IgM anti-HAV-positive and the IgM anti-HAV-negative (includes hepatitis B (153), hepatitis C (57), hepatitis E (153) and unclassified (136)) cases. There is a need for further research on HAV transmission and genotype distribution in Indian sub-continent.