title: Molecular and biological characterization of the endogenous ecotropic provirus of BALB/c mice.
abstract: We have isolated two identical molecular clones of the single, endogenous ecotropic provirus of BALB/c mice. The BALB/c clones are approximately 1/10 as infectious as an exogenous proviral clone derived from AKR mice, p623. Transfection of mouse cells with each BALB/c proviral clone yielded XC-negative, N-tropic, ecotropic virus. Cotransfection of subgenomic fragments of p623 and the BALB/c provirus did not increase infectivity to the level observed for p623; however, a 292-base-pair fragment of the p623 env gene was found to rescue XC-plaque formation. Sequence analysis showed that the XC-negative BALB/c provirus differed from the XC-positive AKR-derived provirus at a single nucleotide at the junction of the gp70 and p15E envelope proteins. Extensive sequence analysis of the BALB/c endogenous provirus showed that it differed from the sequence of the AKR-derived provirus at approximately 0.5% of 4,500 sequenced nucleotides. In addition, the BALB/c long terminal repeat contains a single copy of the enhancer-containing sequences that are repeated twice in p623. The limited variation between the ecotropic proviruses of BALB/c mice and AKR mice suggests that few cycles of reverse transcription separate these viral genomes.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D003588:Cytopathogenic Effect, Viral; D004262:DNA Restriction Enzymes; D004279:DNA, Viral / Q000235:genetics; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D005814:Genes, Viral; D009052:Leukemia Virus, Murine / Q000235:genetics*; D051379:Mice; D008806:Mice, Inbred AKR / Q000382:microbiology; D008807:Mice, Inbred BALB C / Q000382:microbiology*; D011499:Protein Processing, Post-Translational; D012091:Repetitive Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid; D014162:Transfection; D014759:Viral Envelope Proteins / Q000235:genetics; D014779:Virus Replication
chemical_list: D004279:DNA, Viral; D014759:Viral Envelope Proteins; D004262:DNA Restriction Enzymes