Comparison of the neutralizing and ELISA antibody titres to measles virus in human sera and in gamma globulin preparations.

Measles virus infection as well as measles vaccination induces a long-lasting immune protection. Specific antibodies have been proven to be associated with this immune protection, since measles immunity can be transferred by immune globulin application (passive immunisation). The neutralisation test (NT) is regarded as the gold standard method for measles immunity because it measures functional neutralising antibody, while with the ELISA, which is often based on cell culture grown native virus antigens, predominantly antibodies to the nucleoprotein antigen were detected. To compare the results of NT and ELISA 199 individual sera and 364 gamma globulin samples, which were made from plasma pools, were tested. Qualitative results showed that the sensitivity of the ELISA was 141/144 (97.9%) and specificity was 48/55 (87.3%) when compared to the NT and focused to the patient samples. For the gamma globulin samples the sensitivity and specificity was 100%. As expected no measles NT negative plasma pool samples were found. The present study showed that with increasing NT-titre, the ELISA-values also rise. False negative ELISA results were obtained in 1.5% of patient sera, mainly containing low levels of neutralising antibody. In both antibody tests seropositive specimens revealed a quite good to moderate correlation. Taken together, the measles IgG ELISA is adequately for immunity testing and identifying of seronegative individuals for vaccination.