Recombinant vaccinia virus primes and stimulates influenza haemagglutinin-specific cytotoxic T cells.

The ability of vaccinia virus to accept and express cloned genes encoding immunologically important proteins of unrelated viruses and malarial parasites has suggested a novel approach to the development of live vaccines. Vaccinia virus recombinants retain infectivity and stimulate synthesis of specific antibodies to the cloned gene products in vaccinated animals. Moreover, animals inoculated with recombinants expressing the influenza virus haemagglutinin (HA), the hepatitis B virus surface antigen, and type 1 herpesvirus glycoprotein D were protected against subsequent challenge with the corresponding virus. For maximal effectiveness, vaccines should produce cellular as well as humoral immunity. We now report that a vaccinia virus recombinant, expressing the influenza HA, primes and stimulates a specific murine cytotoxic T-lymphocyte (CTL) response. Histocompatible cells infected with this recombinant also serve as targets for CTLs. These properties make vaccinia virus a unique tool for studying cell-mediated immunity and enhance the attractiveness of this vector for production of live vaccines.