Serological response to hepatitis E virus genotype 3 infection: IgG quantitation, avidity, and IgM response

Abstract Sequential sera were collected from 18 acute cases of UK‐acquired hepatitis E. The virus strains in all cases were of genotype 3. The IgM and IgG response to acute infection were documented over time using EIA kits based on a peptide antigen, pE2, which is derived from a genotype 1 strain of hepatitis E virus (HEV). Ninety‐five percentage of acute sera were IgM positive; after 6 months or more only 12% remained positive. The kit was adapted to quantify the IgG response (in WHO U/ml) and to determine antibody avidity. Following acute infection, anti‐HEV IgG concentrations rose between 6.9‐ and 90‐fold. IgG avidity was low (<25%) in most acute sera. After 6 months IgG avidity was greater than 50% in all cases. One patient with a poor IgM response and high avidity antibody in acute sera may have had a second HEV infection. Taken together, these results confirm that the pE2‐based EIA kits are suitable for diagnosing acute HEV genotype 3 infection. With simple modifications the IgG kit can measure anti‐HEV concentration and avidity, which can be used to confirm acute infection. J. Med. Virol. 80:95–101, 2008. © 2007 Wiley‐Liss, Inc.