Ecotropic andMinkCellFocus-Forming MurineLeukemia Viruses Integrate inMouseT,B,andNon-T/Non-B CellLymphomaDNA

Structures ofsomatically acquired murineleukemia virus (MuLV)genomespresent intheDNA ofa large panel ofMuLV-induced C57BLandBALB/cB andnon-T/non-B cell lymphomas werecompared withthose present inMuLV-induced T-cell lymphomas induced inthesame low-"spontaneous"-lymphoma-incidence mice. Analyses were performed withprobes specific forthegp7O, pl5E,andU3-long terminal repeat (LTR) regions ofecotropic AKV MuLV anda minkcell focus-forming virus(MCF)-LTRprobeannealing with U3-LTRsequencesofaunique endogenous xenotropic MuLV,whichalsohybridizes withU3-LTRsequences ofa substantial portion ofsomatically acquired MCF genomesinspontaneous AKR thymomas. TheDNAsof bothT-andB-cell tumorsinduced byneonatal inoculation withthehighly oncogenic C57BL-derived MCF 1233 virus predominantly contain integrated MCF proviruses. Incontrast, theDNAsofmore slowly developing B andnon-T/non-B cell lymphomas induced bypoorly oncogenic ecotropic orMCF C57BLMuLV isolates mostly contain somatically acquired ecotropic MuLV genomes.Approximately 50% ofthespontaneous C57BL lymphomaDNAscontain somatically acquired MuLV genomes.Noneoftheintegrated MuLV proviruses annealed withtheMCF-LTRprobe, whichindicates a clear difference inLTR structure witha substantial portion ofthesomatically acquired MuLV genomespresent intheDNA ofspontaneous AKR thymomas. This study stresses a dominant role ofMuLV withecotropic gp7OandLTR sequencesinthedevelopment ofslowly arising MuLV-induced B andnon-T/non-B celllymphomas.