Introduction of protein or DNA delivered via recombinant Salmonella typhimurium into the major histocompatibility complex class I presentation pathway of macrophages

Recombinant (r) Salmonella typhimurium aroA strains which display the hen e gg ovalbumin OVA(257-264) peptide SIINFEKL in secreted form were constructe d. In addition, attenuated rS. typhimurium pcDNA-OVA constructs harbouring a eukaryotic expression plasmid encoding complete OVA were used to introduc e the immunodominant OVA(257-264) epitope into the major histocompatibility complex (MHC) class I presentation pathway. Both modes of antigen delivery (DNA and protein) by Salmonella vaccine carriers stimulated OVA(257-264)-s pecific CD8 T-cell hybridomas. An in vitro infection system was established that allowed both rSalmonella carrier devices to facilitate MHC class I de livery of OVA(257-264) by coexpression of listeriolysin (Hly) or by coinfec tion with rS, typhimurium Hlys (Hess J., Gentschev I., Mike D., Welzel M., Ladel C., Goebel W., Kaufmann S.H.E., Proc. Natl. Acad. Sci. USA 93 (1996) 1458-1463). Coexpression of Hly and coinfection with rS. typhimurium Hlys s lightly improved MHC class I processing of OVA. Our data provide further ev idence for the feasibility of attenuated, Hly-expressing rS. typhimurium ca rriers secreting heterologous antigens or harbouring heterologous DNA as ef fective vaccines for stimulating CD8 T cells in addition to CD4 T cells. (C ) Elsevier, Paris.