Biologic and immunologic characterization of the soluble skin-test antigen of varicella-zoster virus.

A sensitive method for assay of the potency of the skin-test antigen of varicella-zoster virus was established. Potency was determined by a reverse passive hemagglutination test, and the results correlated well with the cutaneous reaction of sensitized guinea pigs and an immune human adult to the antigen. Cutaneous reactivity was not induced by repeated inoculation of the antigen, but humoral neutralizing antibody was detected in most guinea pigs when a large amount of antigen was used. No cutaneous cross-reactivity between varicella-zoster virus and herpes simplex virus was noted; however, positive cutaneous reactions and neutralizing antibody responses to homologous virus were detected in infected guinea pigs. These results suggest that both skin tests are specific and support the clinical usefulness of the varicella-zoster skin test.