Molecular cloning of AKR xenotropic murine leukemia virus unintegrated proviral DNA

Abstract Superhelical proviral DNA of AKR xenotropic murine leukemia virus was purified from agarose gels and cloned in lambda Charon 28 DNA ( Bam HI sites). Nine viral DNA recombinants were identified and mapped with 12 restriction endonucleases. Three classes of cloned viral DNA inserts were found: (1) Six inserts were apparently full-length 9.0-kb DNA with tandem long terminal repeat (LTR) elements; (2) two inserts contained DNAs with deletions in or adjacent to the LTR regions; (3) a single isolate contained an inversion of 2.3 kb around the LTR in the envelope gene.