ENZYME-LINKED IMMUNOSORBENT ASSAY(ELISA) FOR DETECTION OF MUMPS IgM ANTIBODY

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Serological disgnosis of viral infection is done by the demonstration of a significant increase of antibody during the period from acute to convalscent phases. Bleeding of patients at appropriate times is, however, not always possible and, in many instances, including mumps, only one serum specimen is available. Domonstration of IgM antibody provides the evidence for a recent infection with mumps virus. IgM antibody has usually been determined after separation of IgM fraction from a test serum by centrifugation through sucrose gradient, but the method is not easy for a routine serodiagnosis. We tried to develop a less sophisticated and less time-consuming procedure for determination of IgM antibody against mumps virus. We have developed the method in which IgM of a test serum is captured by anti-human IgM antibody attached to the solid phase. Purified mumps virus and peroxidase-conjugated monoclonal antibody specific to mumps virus NP protein then followed in succession. The color generated by the peroxidase in reaction with the substrate mixture was determined spectrophotometrically: In 24 cases of clinical mumps, the diagnosis of which had been confirmed by a significant rise in antibody titer in IgG-ELISA, IgM antibody was positive in 6 out of 9 sera taken on the first day of illness, in 8 out of 9 on day 2, and in all of 24 on day 5 and thereafter. A follow-up study with 25 cases showed that IgM antibody persisted for as long as 3 months and in one case up to 5 months. These results showed that the method is useful for the diagnosis of recent mumps virus infection.