Measles virus and canine distemper virus target proteins into a TAP-independent MHC class I-restricted antigen-processing pathway

Institute of Virology and Immunobiology, University of Würzburg, Versbacher Str. 7, 97078 Würzburg, Germany 1 Institute of Molecular Biology, University of Zürich, Winterthurer Str. 190, 8057 Zürich, Switzerland 2 Children Hospital, University of Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany 3 Institute of Hygiene and Microbiology, University of Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany 4 Author for correspondence: Stefan Niewiesk. Fax +49 931 201 3934. e-mail niewiesk{at}vim.uni-wuerzburg.de After infection of CEM174.T2 cells [deficient for the transporter of antigen presentation (TAP)] with measles virus (MV) the nucleocapsid protein is recognized by L d -restricted cytotoxic T cells in a TAP-independent, chloroquine-sensitive fashion. Presentation via the TAP-independent pathway requires virus replication. During MV infection of the cell the nucleocapsid as well as the matrix protein enter the endolysosomal compartment as indicated by colocalization with the lysosomal-associated membrane protein 1 (LAMP-1). Similarly, the nucleocapsid protein of canine distemper virus (CDV) is recognized in a TAP-independent fashion. In addition, a recombinant MV expressing bacterial -galactosidase protein is able to introduce the recombinant antigen into the TAP-independent pathway whereas a vaccinia virus expressing -galactosidase is not. These data and a report about TAP-independent recognition of parainfluenza virus type 1 suggest that members of the Paramyxoviridae family regularly introduce viral proteins into the TAP-independent antigen-processing pathway.