Induction of monocyte procoagulant activity by murine hepatitis virus type 3 parallels disease susceptibility in mice

A number of investigators (26, 27) have demonstrated that the susceptibility of adult mice of different strains to MHV, using mortality as the index, parallels the cytopathic effects that the virus has in mouse peritoneal macrophages in vitro. The cellular basis for the resistance of A strain macrophages is not known; however, it has been observed (26) that resistance can be overcome by increasing the infecting dose, suggesting that resistant strains do not entirely lack receptors for MHV-3. It has also been demonstrated (43) (44) (45) that young or immunologically depressed A strain mice develop disease similar to that occurring in susceptible strains, in contrast to the fully resistant adult A mouse. Further observations suggest that the state of susceptibility is under the influence of T cells (46) (47) (48) , humoral factors (28) , and splenic adherent cells (27) . It has also been demonstrated (46, 47) that nude mice and mice treated with cyclophosphamide (49) develop full susceptibility to MHV-3 infection. Thus, it appears that a complex series of interactions between lymphocytes, monocytes, and humoral factors may be required to explain the balance between susceptibility or resistance to this virus.