Correlation between the neutralizing activity of human serum against Herpes simplex virus and a simian herpesvirus (SA8).

Cross-neutralization tests were carried out between various Group A and Group B herpesviruses using rabbit or rooster antisera. The viruses studied included herpes simplex, SA8 (a simian herpesvirus isolated from vervet monkeys), SA6 (a simian cytomegalovirus isolated from vervet monkeys), infectious bovine rhinotracheitis, and pseudorabies. Reciprocal cross-reactivity was found between HSV and SA8 (both Group A herpesviruses), but not between other virus pairs. Sera from certain healthy (normal) humans were shown to contain neutralizing antibodies against both HSV and SA8, but not against IBR or PRV. The neutralizing activity of these human sera against HSV and SA8 was localized in the 7 S antibody fractions. The results suggested that neutralization of SA8 by human serum was due to a heterotypic response between SA8 and antibody to HSV, rather than to immunogenic exposure of these individuals to SA8.