KLRA1P and cytomegalovirus infection: Mice harboring only the inhibitory Ly49 family members, which bind to MHCIs (Held et al., 1996; Yu et al., 1996; Hanke et al., 1999) as well as the CMV MHCI homolog, m157 (Arase et al., 2002; Smith et al., 2002), cannot survive the CMV infection.