Discrete regions of sequence homology between cloned rodent VL30 genetic elements and AKV related MuLV provirus genomes

Abstract

Southern blot analyses using reduced stringency hybridization conditions have been employed to search for sequence homologies between rodent VL30 genes and murine leukemia virus (MuLV) proviruses. These constitute two classes of transposon-like elements previously believed to be genetically unrelated. Our results demonstrate that cloned representatives of both ecotropic and xenotropic-like proviruses shared is crete regions of sequence homology with VL3O genes of both rat and mouse origin . These regions of homology existin both 3' and 5' halves of the MuLV genome but do not include extensive portions of the long terminal repeat(LTR) or a 0.4 Kbp segment of the enu gene specific for recently acquired ecotropic-type MuLV p roviruses . DNA sequencing, however, revealed that the short inverted terminal repeat sequence of MuLV proviral LTRs is almost perfectly conserved at the terminus of an integrated mouse VL30 gene. These results suggest that recombination events with rodent VL.30-type sequences occurred during early MuLV evolution. The strong conservation of the inverted terminal repeat sequence may reflect a common integration mechanism for VL30 elements and HuLV proviruses.