Genetic variability of hepatitis E virus within and between three epidemics in India

Hepatitis E virus (HEV) is an important cause of epidemic and sporadic acut e viral hepatitis in many developing countries, including India. We evaluat ed the genetic variability within two regions (a 476-nt long ORF1 segment a nd a 304-nt long ORF2 segment) from specimens collected during three outbre aks in the cities of Karnal (1987), Yamunanagar (1989), and Meerut (1996), India, and from one patient, residing in Lucknow, India, who had a case of sporadic hepatitis (1996). Within an outbreak, sequences in the ORF1 and OR F2 regions were 99.3-100.0% identical. However, when strains were compared between outbreaks, identity in the ORF1 and ORF2 region was 97.1-99.2 and 9 6.4-100.0%, respectively. A comparison of these sequences to previously pub lished Indian ORF1 and ORF2 sequences revealed even lower similarities, 95. 2-98.5 and 95.1-98.7%, respectively. One patient in the Meerut outbreak had genomic sequences that differed substantially from the other patients affe cted during this outbreak and probably reflected a sporadic infection. The sporadic hepatitis E strain from Lucknow clustered with a previously descri bed HEV strain from a patient with fulminant hepatic failure (FHF). Our dat a suggest that the ORF1 and ORF2 segments can be used to study the molecula r epidemiology of HEV infection and indicate that much remains to be determ ined about the genetic variability of Indian HEV strains. (C) 1999 Publishe d by Elsevier Science B.V. All rights reserved.