Identification of putative endogenous proviral templates for progenitor mink cell focus-forming (MCF) MuLV-related RNAs.

Murine leukemia virus (MuLV)-related RNAs exhibiting different env deletions are believed to participate in the generation of leukemogenic mink cell focus-forming (MCF) viruses. We have cloned an endogenous MuLV provirus from AKR/J mouse DNA, designated as A-2, which may serve as template for the env-deleted E2 MuLV RNA, expressed in GIX+ mice (D.E. Levy et al., J. Virol. 56, 691-700 (1985]. We have also isolated an endogenous MCF-related DNA, A-1, which shared close sequence homology with the 7.2-kb RNA expressed in AKR mice (F. Laigret et al., J. Virol. 62, 376-386 (1988] and sustained an identical env deletion. The data indicate that putative precursor MCF-related RNAs are transcribed from a heterogenous family of env-deleted endogenous MuLV DNAs.