Susceptibility of W/WV mice to murine cytomegalovirus infection.

The susceptibility of congenitally anemic W/WV mice to infection with murine cytomegalovirus (MCMV) was examined. W/WV mice showed a higher mortality rate and shorter survival time after MCMV infection than did their +/+ littermate mice. In addition, W/WV mice showed a lower plaque-forming unit (PFU) per 50% lethal dose (LD50) and produced higher titers of infectious virus in various organs. The mortality rate and survival time of W/WV mice which received a bone marrow graft 4 weeks before infection was completely restored to the level for +/+ mice, suggesting the importance of the cells of myeloid origin. Although natural killer (NK) activity of W/WV mice was comparable to that of +/+ mice before infection, marked reduction was observed after MCMV infection. Furthermore, OK-432 treatment failed to enhance NK activity of W/WV mice. Impaired NK response was also completely restored by bone marrow grafting 4 weeks before infection. The level of serum interferon (IFN) of infected or uninfected W/WV mice was comparable to that of +/+ mice. Therefore, impaired NK inducibility seems to be responsible, at least in part, for the high susceptibility of W/WV mice to MCMV infection.