Molecular epidemiology of HCV infection among acute and chronic liver disease patients in Kolkata, India

Abstract

In recent years, hepatitis C virus (HCV) infection is gaining importance in Asian countries. Recent studies conducted in different parts of the world revealed that there is a genotypic correlation of disease severity and treatment outcome. A detailed study was carried out to delineate the genotypic distribution of HCV among acute and chronic liver disease patients in Kolkata, a city in eastern India. Acute and chronic liver disease was diagnosed among patients attending hepatitis clinics in the city. Anti-HCV ELISA was performed on the blood samples of the cases and positive samples were tested for presence of HCV-RNA and genotyping of the samples were carried out by reverse transcription and polymerase chain reaction (RT-PCR) and sequencing. Seroprevalence of HCV infection among acute (11.0%) and chronic (25.3%) hepatitis patients were high and among them 97 (75.8%) and 323 (86.1%) were HCV-RNA positive for acute and chronic hepatitis patients, respectively. Genotyping by PCR showed that the predominant genotype was 3b (42.3%) followed by 3a (28.9%) among acute hepatitis group whereas among chronic hepatitis group, the most prevalent genotypes were 3a (34.7%) and 3b (47.7%). Sequence analysis of the untypeable isolates revealed the presence of a rare subtype 6b. The study revealed very high prevalence of HCV among acute and chronic hepatitis patients with predominance of genotype 3. Subtype 6b was commonly found in Thailand but not in India. The detection of this rare strain of Thai origin reveals the spread of HCV infection from Thailand to other parts of Asia. This observation necessitates further intensive surveillance of HCV infection in India to unravel the distribution of genotypes in the country and to correlate disease severity and treatment outcome to the genotype prevalence.