Demonstration of virus-specific transcriptional activator(s) in cells infected with HTLV-III by an in vitro cell-free system.

Human T cell lymphotropic viruses (HTLV's) differ from most other retroviruses based on the presence of trans-regulatory genes for virus expression. In this study, using an in vitro cell-free transcription system, we demonstrate that nuclear extracts obtained from cells infected with HTLV-III (human immunodeficiency virus, HIV) contain a factor(s) that stimulates transcription specifically from the HTLV-III promoter. Present studies indicate that this activation is mainly involved in the initiation of transcription from the HTLV-III promoter.