Host immune responses after administration of inactivated Venezuelan equine encephalomyelitis virus vaccines. I. Description and characterization of adoptive transfer by immune spleen cells.

Cellular immune responses after immunization with a number of inactivated Venezuelan equine encephalomyelitis (VEE) virus vaccines were evaluated in mice by means of an adoptive transfer system. Formalin-inactivated, TC-83 strain VEE virus vaccine was immunogenic and highly effective in protecting recipient mice against challenge with virulent VEE virus. In contrast to immunization with live TC-83 VEE virus vaccine, however, immunization with inactivated VEE vaccine did not provide donor mice with the capacity to transfer adoptive immunity readily. Only when mice were immunized with inactivated VEE vaccine combined with specific adjuvants (particularly complete Freund's adjuvant or Bordetella pertussis) were donors capable of consistently transferring adoptive immunity. The total dose of inactivated VEE vaccine did not appear to influence the capacity to transfer adoptive immunity. On the other hand, weekly boosters of VEE vaccine and/or administration of vaccine with specific adjuvants did markedly influence donor immune responses.