ENDOGENOUS NONECOTROPIC PROVIRUSES MAPPED WITH OLIGONUCLEOTIDE PROBESFROM THE LONG TERMINAL REPEAT REGION

We characterized endogenous proviruses in C57BL/6J, DBA/2J, and C3H/He J mouse strains with oligonucleotide probes derived from long terminal repeat (LTR) sequences of three classes of nonecotropic murine leukem ia virus. The segregation of proviral-host DNA junction fragments was followed in BXH and BXD recombinant inbred (RI) strain sets, and most fragments mapped readily to defined chromosomal regions. Most of the L TR fragments appear to correspond to proviruses mapped previously with oligonucleotide env region probes of the same viral class. At least 2 2 elements represent new proviral loci, no more than half of which may be solo LTRs, and an additional six may correspond to proviruses iden tified previously with less specific hybridization probes. Together wi th proviruses identified previously with env probes, the LTR probe-rea ctive elements represent the majority of endogenous murine leukemia pr oviruses in the mouse genome.