MHC (major histocompatibility complex) class I molecules are a central weapon in the immune response against viruses. When a virus infects a cell, the cell facilitates the expression of viral antigens on the surface of infected cells, drawing the attention of immune cells called cytotoxic T cells. These immune cells zero in on and destroy the infected cells, together with the invading virus inside them. a protein from the SARS-CoV-2 virus, called ORF 6, suppresses a host cell protein, called NLRC5, responsible for activating the MHC class I pathway. ORF6 hampers cell signalling, which turns off the expression of NLRC5. ORF6 also blocks the function of NLRC5. infectious viruses, including HIV and MERS, are known to also target the MHC class I pathway.
— source Hokkaido University | Dec 7, 2021