Transcriptase by Intracellular Expression of Single-Chain Variable Fragments To Inhibit Early Stages of the Viral Life Cycle

Novel molecular approaches to inhibit human immunodeficiency virus type 1 (HIV-1) infection have received increasing attention because of the lack of effective antiviral drug therapies in vivo. We now demonstrate that cells can be intracellularly immunized by cytoplasmic expression of single-chain variable antibody fragments (SFv) which bind to the HIV-1 reverse transcriptase (RT) enzyme. The expression of anti-RT SFv in T-lymphocytic cells specifically neutralizes the RT activity in the preintegration stage and affects the reverse transcription process, an early event of the HIV-1 life cycle. Blocking the virus at these early stages dramat-ically decreased HIV-1 propagation, as well as the HIV-1-induced cytopathic effects in susceptible human T lymphocytes, by impeding the formation of the proviral DNA. These data also demonstrate that intracellular, complete SFvs may gain access to viral proteins of the HIV-1 preintegration complex. These SFvs will provide a tool with which to better understand the molecular mechanism(s) involved in restricting viral replication in HIV-1-infected cells. It has been over a decade since the discovery of human immunodeficiency virus type 1 (HIV-1) as the major cause of AIDS. There has been only modest progress in the develop-ment of therapy that may stop or significantly alter the ulti