Pathogenesis of paralysis and lymphoma associated with a wild mouse retrovirus infection. Part 1. Age- and dose-related effects in susceptible laboratory mice.

Wild mouse ecotropic retrovirus (Cas-Br-M) induced paralysis and non-thymic lymphomas in susceptible NIH Swiss and NFS/N mice. The incidence of paralysis was highest and latency shortest in mice receiving high doses of virus. Lower dose inoculation and inoculation of older mice produced less paralysis with longer latency, but resulted in more lymphomas. However, 10-day-old mice did not develop paralysis and had fewer lymphomas. Anti-Cas-Br-M antibody was detectable in sera from 10-day-old infected mice but not from paralyzed mice. These data suggest that while paralysis and lymphoma may result from different virus-host interactions, the development of immunocompetence may play a role in the age-dependent resistance to Cas-Br-M-associated paralysis and lymphoma in these mice.