Trans-activation of the human immunodeficiency virus long terminal repeat sequence by DNA viruses

To investigate whether DNA viruses can augment gene expression of the human immunodeficiency virus (HIV), cotransfection experiments were carried out in which a recombinant plasmid containing the HIV long terminal repeat (LTR) linked to the chloramphenicol acetyltransferase (CAT) gene was transfected into cultured cells along with plasmids containing DNA from various distinct classes of DNA viruses. Molecular clones containing JC virus, BK virus, lymphotropic papovavirus, bovine papilloma virus, type 1 herpes simplex virus (HSV-1), and varicella-zoster virus sequences increased CAT expression directed by the HIV LTR. Trans-activation of the HIV LTR varied in different cell lines, but in each case the HIV tat gene product elicited the greatest stimulation. Primer-extension assays specific for HIV LTR mRNA revealed increased levels of steady-state RNA following transfection with HIV tat as well as with several of the DNA viruses. Virus-specific RNA expression paralleled the stimulation of CAT activity. More-than-additive effects were observed at both the RNA and protein levels when tat plus type 1 herpes simplex virus DNAs or tat plus JC virus DNAs were transfected into cells with the HIV LTR-CAT plasmid. These data suggest that coinfection of cells by HIV and some DNA viruses can stimulate the expression of HIV.