Enzyme-linked immunosorbent assay (ELISA) for detection of IgM and IgG antibodies to Japanese encephalitis virus in sera from experimentally infected swine.

Abstract

An enzyme-linked immunosorbent assay (ELISA) using peroxidase conjugate was adapted to detect IgM and IgG antibodies of Japanese encephalitis (JE) in sera from two experimentally infected swine. Using anti-swine IgM or IgG conjugate, ELISA IgM and IgG antibody titers to JE Virus were compared with hemagglutination inhibition (HI) titers before and after 2-Mercaptoethano1 (2-ME) treatment of the sera. ELISA IgM antibody was detected immediately after the disapperence of viremia, and the titers reached maximum in the early stage of infection but decreased in the convalescent period. ELISA IgG antibody, however, appeared later than IgM antibody, and the IgG titers changed to become predominate over the IgM titers in the convalescent sera. The titers in ELISA corresponded well with HI titers. It was found that ELISA could detect IgM antibody even though HI test could not detect it. Anti-swine IgM and IgG conjugates for ELISA were specific enogh to differentiate IgM and IgG sub-class antibodies in the swine serum. Aceton-ether (AE) zonal antigen was found to produce less non-specific reaction in ELISA as compared with sucrose-aceton (SA) antigen. Thses results suggest that ELISA has advantages over the HI test for serodiagnosis of JE in swine.