Transacting transcriptional activation of human spumaretrovirus LTR in infected cells

The long terminal repeat (LTR) of the human spumaretrovirus (HSRV) was examined with respect to its ability to function as transcriptional promotor in virus-infected and uninfected cells. Transient transfections using a plasmid in which the 3' LTR of HSRV was coupled to the bacterial chloramphenicol acetyltransferase (cat) gene revealed that the level of HSRV LTR-directed cat gene expression was markedly increased in HSRV-infected cells compared to uninfected cells. Northern blot analysis of cat mRNA from transfected cultures suggests that transactivation of HSRV-directed gene expression occurs at the transcriptional level.