Friend disease in BDF1 mice is characterized by early transient splenomegaly followed by a long period of remission before the mice die from an exacerbation of their disease. In the experiments reported, remission occurred in mice

Friend disease in BDF1 mice is characterized by early transient splenomegaly followed by a long period of remission before the mice die from an exacerbation of their disease. In the experiments reported, remission occurred in mice inoculated at 8 weeks of age or older. The early and late phases of Friend disease in BDF1 mice were indistinguishable from those seen in BALB/c mice. However, transplantable tumors could be established much more readily in the former strain than in the latter. The spleens of some mice in remission showed no evidence of Friend disease. These mice could relapse, so their spleens probably still harbored Friend virus. Remissions were most common in mice I 2 weeks old at inoculation and were more frequent and longer lasting in mice receiving small inocula of virus. Serial passage of the virus in newborn BDF1 mice did not abolish the remission, indicating the importance of “hostfactors.― Only low levels of neutralizing antibodies could be detected in serum, although the offspring of mothers with minimal focal disease were partially resistant to challenge with Friend virus. Mice with remittent Friend disease demonstrated transplantation resistance to challenge with a syngeneic, noninfectious Friend virus-induced reticulum cell sarcoma, but this was not evident until after remission had occurred.