ENHANCED GENERATION OF CYTOTOXIC T-LYMPHOCYTES USING RECOMBINANT VACCINIA VIRUS EXPRESSING HUMAN TUMOR-ASSOCIATED ANTIGENS AND B7 COSTIMULATORY MOLECULES

In this work, we addressed the possibility to enhance the ''in vitro'' generation of CTLs recognizing tumor-associated antigens (TAAs) by us ing an inactivated recombinant vaccinia virus encoding B7.1 and B7.2 c ostimulatory molecules (rVV-B7.1/2). Antigen presenting cells (APCs) i nfected by rVV-B7.1/2 and pulsed with MART-1/Melan-A(27-35) HLA-A2.1-r estricted peptide induced significantly higher specific cytotoxic acti vity than peptide-loaded APCs infected by wild-type VV, both in VV-sen sitized and naive donors. When APCs were infected with a rVV encoding both MART-1/Melan-A(27-35) and B7-1/2 (rVV-B7.1/2-M), a significantly more effective CTL generation was observed as compared with cultures s timulated by APCs infected with a rVV encoding the TAA epitope only (r VV-M), These enhancing effects were detectable irrespective of a previ ous W-specific sensitization. Most importantly, fibroblasts, devoid of antigen-presenting capacity upon peptide pulsing or infection with rV V-M, could be turned into effective APCs after infection by rVV encodi ng TAA epitopes and costimulatory molecules. In these experiments, by using separate recombinant viral constructs, we observed a predominant role of B7-1 as compared with B7-2 in the induction of TAA-specific C TLs, Taken together, our data indicate that replication-incompetent rV V encoding TAA epitopes and costimulatory molecules are able to induce highly effective generation of tumor-specific CTLs. Therefore, these vectors could represent valuable clinical tools for immunotherapy of m elanoma patients.