- The r144 major histocompatibility complex class I-like gene of rat cytomegalovirus is dispensable for both acute and long-term infection in the immunocompromised host. Beisser, P.S., Kloover, J.S., Grauls, G.E., Blok, M.J., Bruggeman, C.A., Vink, C. J. Virol. (2000)