The Tortorella laboratory focus is to study how viruses evade immune detection. The human cytomegalovirus (HCMV), a member of the herpes virus family, can be used as a model to study strategies that viruses use to avoid the immune system by interfering with MHC class I antigen presentation. HCMV encodes a number of proteins derived from the unique short (US) region of the HCMV genome referred to as US2, US3, US6 and US11 that prevent the surface expression of Class I molecules. The US3 and US6 gene products interfere with Class I trafficking to the cell surface and loading of antigenic peptides into the Cla! ss I complex, respectively. US2 and US11 target the class I molecules for destruction by the proteasome.