MHC I-dependent antigen presentation is inhibited by poliovirus protein 3A

The effects of poliovirus 3A protein expression and poliovirus infection on the presentation of hepatitis C virus antigens in cultured chimpanzee cell s were examined. Expression of poliovirus 3A protein inhibits protein secre tion when expressed in isolation and was sufficient to protect chimpanzee c ells from lysis by hepatitis C virus-specific cytotoxic T cells in standard Cr-51-release assays. Poliovirus infection also inhibited antigen presenta tion, as determined by decreased cytotoxic T cell activation. A mutation in 3A that abrogates the inhibition of protein secretion also abolished the e ffects of poliovirus on antigen presentation. These results demonstrate tha t the inhibition of secretion observed in poliovirus-infected cells substan tially reduces the presentation of new antigens on the cell surface. These observations may reflect a general mechanism by which nonenveloped viruses such as poliovirus and other viruses that do not require a functional prote in secretory apparatus can evade detection by the cellular immune response.