Enzyme immunoassay versus plaque neutralization and other methods for determination of immune status to measles and varicella-zoster viruses and versus complement fixation for serodiagnosis of infections with those viruses.

Results by an enzyme immunoassay method (EIA) performed at one serum dilution and results by indirect immunofluorescence (IFA) and hemagglutination inhibition (HI) tests performed at step dilutions were correlated with results by a neutralization test (50% plaque neutralization [PN]) performed at step dilutions on single serum samples for serologic evaluation of immunity status to measles virus. PN results were taken as true indicators of immunity, and the other tests were evaluated on that basis. The predictive value of a positive result being positive also by PN was 95.3% for HI and 93.3% for EIA and IFA. The predictive value of a negative result being negative also by PN was 81.1% for HI, 100% for EIA, and 75.0% for IFA. A similar study on immunity status to varicella-zoster virus by EIA and by an anticomplement immunofluorescence test versus PN showed a 100% predictive value of a positive or negative result by EIA. By the anticomplement immunofluorescence test, the predictive value of a positive result was 97.7%, and that of a negative result was 88.5%. Studies on the comparative ability of EIA versus complement fixation (CF) to detect significant changes in antibody concentration between acute-phase and convalescent-phase serum samples indicative of a current infection were also done. Both tests were satisfactory for the serodiagnosis of measles or varicella-zoster virus infections. However, EIA was preferable to CF because it was less technically difficult, less labor intensive, and could be performed on sera that were anticomplementary in CF reactions.