MURINE T-HELPER CELL IMMUNE-RESPONSE TO RECOMBINANT VACCINIA VENEZUELAN EQUINE ENCEPHALITIS-VIRUS

The T-helper (Th) cell immune response following immuniziation of C3H (H-2(k)) mice with a recombinant vaccinia (VAC) virus (TC-5A) expressi ng the structural proteins (capsid, E1 and E2) of the attenuated vacci ne strain (TC-83) of Venezuelan equine encephalitis (VEE) virus was co mpared with the immune response induced in mice after immunization wit h TC-83 virus. TC-5A virus elicited Th cells that strongly recognized both VAC and TC-83 viruses in in vitro lymphoblastogenesis tests. Th-c ell activation was associated with elevated levels of interleukin-2. T C-5A virus induced long-term humoral immunity; VEE virus-binding and n eutralizing antibodies were detected in mouse sera collected from mice 16 months after a single immunization.