Occurrence of hepatitis E virus IgM, low avidity IgG serum antibodies, andviremia in sporadic cases of non-A, -B, and -C acute hepatitis

Serum samples were taken from 57 patients with sporadic non-A, -B, and -C ( Non A, B, C) acute hepatitis at different times after onset of the disease and tested for the presence of the hepatitis E virus (HEV) RNA, IgM, and lo w avidity IgG antibodies. The viral antibodies were detected using two ELIS A. One assay (GL) was produced using a mixture of recombinant peptides spec ified by ORF2 and ORF3 of the viral genome. The other was produced with an ORF2 specified peptide, pE2. The latter occurs naturally as homodimer, it i s recognized strongly in its dimeric form by human sera and, in the primate model, it confers protection against experimental HEV infection. Nineteen samples were positive for one or more of these acute markers of HEV infecti on, 14 of which were acute sera with elevated ALT levels and 5 were convale scent sera with normal ALT level. The results showed that icteric phase of sporadic hepatitis lasts for about 17 days and it coincides with a period w hen viremia is subsiding as HEV antibodies are developing. Viremia was inte rmittent and all but one of the 5 instances were confined to the icteric ph ase with elevated ALT levels. On two of these occasions, viremia preceded d etection of HEV antibody, on another 2 occasions it was concurrent with the detection of pE2 specific IgM and/or low avidity IgG and only in one case of protracted viremia was the viral genome detected concurrently with avid pE2 IgG antibody. Ten (71%) of the 14 acute sera were reactive for pE2 IgM, eight (57%) were reactive for low avidity pE2 IgG, and six (43%) for the G L IgM. The sensitivity for the diagnosis of acute hepatitis E may be increa sed to 87% by combining pE2 IgM and viremia. GL IgM was detected later, but persisted for a longer period of time than the pE2 antibodies, and it was the only acute antibody detected in the convalescent sera. (C) 2002 Wiley-L iss, Inc.