Photo Credit: C. Goldsmith, CDC The first treatments for HIV-1/AIDS targeted the viral enzymes, reverse transcriptase and protease; more recently, compounds that block viral fusion/entry have also been developed. HIV-1 regulatory proteins are considered to be more difficult drug targets, not least because ways to assay for activity are less clear, but researchers at the University of Pittsburgh have now described an assay for HIV-1 Nef and have identified compounds that block the function of this viral protein. The HIV-1 nef gene was originally believed to inhibit transcription and to be of little importance (hence ‘Negative regulatory Factor’), but the protein is now known to play key roles in viral replication and pathogenesis. Nef is one of the first proteins to be detected after infection of the host cell and has three main functions: it increases viral infectivity, down-regulates surface antigens, and alters signalling pathways to enhance survival of infected T-cells.
Nef binds to src family kinases via their SH3 domains and the Pittsburgh team have exploited Nef’s interaction with Hck (hemopoietic cell kinase) to develop an assay system suitable for high-throughput screening. In the assay, Hck activation is coupled to Nef, providing a direct readout of Nef activity. The assay was used to screen a library of 10,000 compounds biased towards kinase and phosphatase inhibitors, but also containing more diverse structures.
The study, which is published in ACS Chemical Biology, establishes that coupling of Nef to one of its known host cell targets provides a viable high-throughput screen which can be used to identify small molecule inhibitors. Including Hck in the assay may also induce relevant conformations of both Hck and Nef that are essential for small molecule inhibitor binding and function, an idea that is supported by the enhanced potency and efficacy of the inhibitors in the kinase assay when Nef is present. It may be possible to use a similar coupled protein approach to identify compounds that block the function of other HIV virulence factors and compounds which inhibit the function of Nef – or other virulence factors – could eventually become new weapons in the fight against HIV/AIDS.
Thanx for the info. Hoping drugs, from these class of compounds in the days to come…..