Determination of virus-specific antigens in extracts from herpes simplex virus-infected cells by a Cr release inhibition test.

A 51cr release inhibition test (CRIT) was developed for determining herpes simplex virus type 1 antigens in infected cell extracts. Among the factors studied were the optimal concentrations of complement, antibody, and infected target cells. Under standardized conditions, the relationship between antigen content and inhibition of chromium release was linear in a semilogarithmic plot, indicating that the antigen content can be determined from testing two dilutions of a given preparation. Other tests showed that infected cells cryopreserved at -70 degrees C for periods exceeding 3 months can be used in CRIT. Five different batches of infected cell extracts were tested in both CRIT and blocking neutralization tests with comparable results being obtained, suggesting that both tests measure the same activity.