PROVIRAL ACTIVATION OF THE C-MYB PROTOONCOGENE IS DETECTABLE IN PRELEUKEMIC MICE INFECTED NEONATALLY WITH MOLONEY MURINE LEUKEMIA-VIRUS BUTNOT IN RESULTING END-STAGE T-LYMPHOMAS

Moloney murine leukemia virus induces myeloid leukemia when inoculated intravenously into pristane-primed adult BALB/c mice. One hundred per cent of these tumors show insertional activation of the c-myb proto-on cogene, and reverse transcriptase PCR assays have shown that the c-myb activation could be detected soon after infection. We tested BALB/c a nd NIH Swiss mice that had been inoculated as newborns with Moloney mu rine leukemia virus, under which conditions they develop T lymphomas e xclusively. Reverse transcriptase-PCR assays indicated that c-myb acti vations were detectable soon after neonatal infection. However, none o f the resulting T lymphomas contained c-myb activations. The implicati ons of these results to the timing of proto-oncogene activations in le ukemogenesis and the specificity of proto-oncogene activations for dif ferent diseases are discussed.