CHARACTERIZATION OF IN-VIVO PRIMARY AND SECONDARY CD8(-CELL RESPONSESINDUCED BY RECOMBINANT INFLUENZA AND VACCINIA VIRUSES() T)

We characterized the in vivo primary and secondary murine CD8(+) T cel l responses induced by immunization with influenza and vaccinia viruse s, which were engineered to express the same H-2K(k)- and H-2K(d)-rest ricted epitopes. Our results show that the induction and magnitude of the primary CD8(+) T cell response closely depends on the viral dose u sed for immunization, while it is not affected by the route of immuniz ation. The induction of secondary CD8(+) T cell responses appears to b e highly restricted, as suggested by the lack of in vivo expansion of antigen-specific CD8(+) T cells after repeated immunization with the s ame virus. In contrast, a 20- to 30-fold increase in the frequency of antigen-specific CD8(+) T cells could be induced after combined immuni zation with recombinant influenza and vaccinia viruses. These findings may provide the basis for the development of new prophylactic and the rapeutic strategies to prevent or control intracellular infections and certain malignancies. (C) 1996 Academic Press, Inc.