RFs have been found to target cryptic epitopes of IgG heavy chains, presumably being released by lysis of EBV-infected B cells (123) and MHC-II molecules with SE motives (certain HLA-DRB1 alleles) have been found to be optimal ligands for EBV gP42, thus favoring EBV infection of B cells with these forms of MHC-II (31). Here, HLA-DRB1 is linked to Epstein-Barr virus infection.