A microneutralization enzyme immunoassay for antibody to human cytomegalovirus

We have developed a relatively rapid, sensitive and quantitative microneutralization assay for antibody to human cytomegalovirus (HCMV). Cell monolayers in 96-well microtiter plates inoculated with pre-incubated virus-antibody mixtures were fixed after 3 days. Infectious foci were stained with peroxidase-labeled human monoclonal antibody to a 64 kDa immediate early antigen of HCMV, and the plates were read at OD450. The 50% neutralization titer of the antibody was calculated. A study with 20 human sera and a human monoclonal antibody which neutralizes virus showed that this microneutralization enzyme immunoassay is more sensitive than, and as quantitative as, the conventional plaque reduction assay for antibody to HCMV. The neutralizing antibody titers of each sample measured by these two methods showed good correlation (n = 19, r = 0.884). Thus, this new assay is a useful and valid alternative to the conventional method for mass screening of sera and hybridoma fluids, and considerably more rapid.