EXPRESSION AND DIAGNOSTIC UTILITY OF HEPATITIS-E VIRUS PUTATIVE STRUCTURAL PROTEINS EXPRESSED IN INSECT CELLS

The full-length putative structural proteins encoded by open reading f rame 2 (ORF2) and ORF3 of hepatitis E virus have been cloned and expre ssed in recombinant baculovirus. Sera obtained from 28 Sudanese pediat ric patients with acute hepatitis and 19 pediatric control patients we re analyzed for reactivity to hepatitis E virus by using the baculovir us-expressed ORF2 and ORF3 proteins in a Western blot (immunoblot) for mat. Seventeen of the 18 patients classified as having non-A, non-B he patitis, without acute antibody markers for hepatitis A, B, or C virus es, Epstein-Barr virus, or cytomegalovirus, were shown to have immunog lobulin M (IgM) antibodies to the recombinant ORF2 protein, as did two patients with chronic hepatitis B, three of seven patients with acute hepatitis A, and one patient with acute hepatitis B. None of the 19 c ontrol patients had IgM antibodies against the ORF2 or ORF3 proteins. The Western blot assay using the baculovirus-expressed ORF3 protein di d not appear to be as sensitive as the assay based on the ORF2 protein . Only 10 of the patients classified as having non-A, non-B hepatitis had IgM antibodies to the baculovirus-expressed ORF3 protein. We concl ude that a Western blot assay which uses a baculovirus-expressed ORF2 protein is both sensitive and specific for diagnosing acute hepatitis E.