An internal deletion enhances the transcriptional activity of a recombinant retrovirus in hematopoietic cells in vivo.
Lv-myc is a recombinant retrovirus that spontaneously arose during experiments designed to express the provirus LNAv-myc in the hematopoietic system of bone marrow-reconstituted mice (L. Bonham, K. MacKenzie, S. Wood, P. B. Rowe, and G. Symonds, Oncogene 7:2219-2229, 1992). The recombinant provirus is of interest because it is able to promote long terminal repeat-initiated transcription in hematopoietic cells in vivo, whereas the parental provirus, LNAv-myc, is transcriptionally repressed in the same cells. Here we report that Lv-myc was generated by precise deletion of the neomycin resistance gene (neo) and the human gamma-actin promoter from LNAv-myc. In comparison with LNAv-myc, no sequence alterations in the viral regulatory regions of Lv-myc were detected. Thus, it appears that neo and/or the gamma-actin promoter exerted a cis-acting repressor effect on the long terminal repeat of LNAv-myc in vivo. The origin of Lv-myc was also investigated, and it was shown that Lv-myc was harbored as a productive provirus in a G418-resistant subpopulation of the LNAv-myc producer cell line, psi 2AV. It appears that Lv-myc arose during propagation of the psi 2AV cell line. Repeated sequence detected at the sites of the deletion suggest that Lv-myc was generated by a template misalignment during reverse transcription of LNAv-myc.
MacKenzie
K L
KL
Children's Medical Research Institute, Wentworthville, New South Wales, Australia.
Bonham
L
L
Symonds
G
G
D000199:Actins / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D004352:Drug Resistance, Microbial / Q000235:genetics; D017353:Gene Deletion; D006413:Hematopoietic System / Q000382:microbiology; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011533:Proviruses / Q000235:genetics*; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D012190:Retroviridae / Q000235:genetics*; D014158:Transcription, Genetic
D000199:Actins