TAP1‐independent loading of class I molecules by exogenous viral proteins

AbstractPresentation of peptides derived from endogenous proteins on class I molecules needs functional TAP peptide transporters. To reveal whether class I‐associated presentation of exogenous proteins also required the presence of TAP transporters, we assessed in vitro the ability of spleen cells and macrophages from TAP1‐deficient mice (TAP1−/−) to present peptides derived from exogenous recombinant viral proteins on their class I molecules. We found that recombinant glycoand nucleoprotein from lymphocytic choriomeningitis virus and nucleoprotein of vesicular stomatitis virus were presented as efficiently by TAP1 −/− cells as by control cells. Peptide regurgitation was not involved. Since particulate, nonreplicating antigens can efficiently prime anti‐viral cytotoxic T cells in vivo, this new, TAP‐independent pathway of class I‐associated antigen presentation may be applicable for vaccine strategies.