VIRUS-SPECIFIC CYTOTOXIC T-LYMPHOCYTE ACTIVITY ELICITED BY COIMMUNIZATION WITH HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 GENES REGULATED BY THE BACTERIOPHAGE-T7 PROMOTER AND T7 RNA-POLYMERASE PROTEIN

Cytotoxic T lymphocyte (CTL) activity was assessed in mice immunized w ith DNA plasmids containing the human immunodeficiency virus type 1 (H IV-1) gp120 envelope (pTMIgp120) or p55(gag) (pTMIgag) gene regulated by the bacteriophage T7 promoter, Immunization with either plasmid res ulted in CTL activity against class I major histocompatibility complex -restricted viral epitopes when coadministered with a recombinant vacc inia virus expressing the T7 RNA polymerase protein (T7 RNAP) but not a control vaccinia virus, Recombinant vaccinia-T7 RNAP virus (VTF7-3) could be replaced with a noninfectious source of T7 RNAP, A three-comp onent vaccine consisting of pTMIgag, a recombinant subunit T7 RNAP pro tein, and a plasmid (pT7T7) encoding T7 RNAP under the control of its own promoter induced gag-specific CTL activity, Intramuscular immuniza tion with the pTMIgag plasmid delivered with either the T7 RNAP protei n or pT7T7 plasmid alone also induced HIV-l-specific CTL, Thus, there is adventitious expression of the pT7T7 plasmid in vivo, and enough T7 RNAP is produced to result in production of p24(gag) protein from the pTMIgag plasmid, The results demonstrate that regulated expression of genes in vivo is possible with this T7-based expression system, and m ay be useful in vaccine settings where short-term cytoplasmic expressi on of protein in antigen presenting cells is desired.