Adenovirus Proteins And Mhc Expression

Publisher Summary It is noteworthy that Class I MHC molecules are present in most somatic cells and constitute an absolute prerequisite for the effector phase of the specific cytolytic immune response. This chapter reviews the mechanisms that have evolved by Adenoviruses, using which they are able to reduce or abolish the T-cell dependent cytolytic response by modulating the cell surface expression of class I molecules in infected and transformed cells. Most viral serotypes achieve these ends by synthesizing a protein that binds to class I antigens in the endoplasmic reticulum (ER) and impedes the transport of these molecules to the cell surface. However, viruses belonging to the highly oncogenic subgenus A do not affect the cIass I antigen expression during acute infection. Instead, they are distinct from other adenoviruses in that they specifically down-regulate the level of mRNAs, encoding MHC class I antigens, in virally transformed cells. The virus-induced reduction of class I antigen expression drastically diminishes the ability of CTLs to recognize the cells that are infected or transformed by adenovirus.