Germ-line reinsertions of AKR murine leukemia virus genomes in Akv-1 congenic mice.

Congenic mouse strains NIH,Akv-1 and NIH,Akv-2 carry the two high ecotropic virus-inducing loci of the AKR mouse on the NIH Swiss genetic background. Progeny tests of animals in three separate congenic families show that both Avk-1 and Akv-2 are stably transmitted as classical mendelian loci in these mice. However, during the process of inbreeding, additional chromosomal viral loci were detected in several NIH.Akv-1 sublines. These loci appeared only in the progeny of virus-positive females. They segregate with mendelian ratios, are unlinked to markers on chromsome 7 near Akv-1, and are phenotypically expressed as high-virus-inducing loci. The generation of new loci for viurs induction, no doubt resulting from the rare germ-line reintegration of the endogenous ectropic provirus, represents a unique form of gene duplication and rearrangement.