Despite recent progress in anti-HIV therapy, drug toxicity and the emergence of drug-resistant isolates during long-term treatment of HIV-infected patients necessitate the search for new targets that can be used to develop novel antiviral agents. The HIV-1 matrix protein (MA) is a structural protein involved in several stages in the life cycle of the retrovirus. Although MA has long been known to be crucial for virion assembly, details regarding this function, and the domains responsible for mediating it, are still emerging. MA has also been implicated in nuclear import of HIV-1 cDNA and has recently been implicated in novel roles during infection including viral entry/uncoating, cytoskeletal-mediated transport, and targeting viral assembly to lipid rafts. The importance of MA in HIV-1 infection and its potential as an antiviral target have been demonstrated by the success of two strategies designed to block its function, one intrabody-based and another, more recent approach using small molecules. Given the success of these studies and the breadth of functions of HIV-1 MA, we have used a high-throughput computational docking (HTCD) approach to identify small molecules that may potentially bind to and disrupt the functions of HIV-1 MA. From this HTCD screen, we have identified 19 small molecules that are predicted to bind to HIV-1 MA in a structurally and functionally important region. From these 19 compounds, we have determined that eight possess antiviral activity. Importantly, the compounds that display antiviral activity can be grouped into three classes: early-stage inhibitors, late-stage inhibitors, and two compounds that appear to disrupt both early and late events. To our knowledge, these compounds represent the first small-molecule inhibitors that can disrupt both early- and late-stage processes in the replication cycle of HIV-1. In this proposal, we wish to establish the MA-targeted compounds that are suitable for further optimization via medicinal chemistry by investigating their binding affinity, stoichiometry, and binding site on MA (Specific Aim 1) in addition to determining their range, specificity, and mechanism of action (Specific Aim 2). We believe that execution of this cross-disciplinary strategy will successfully identify pharmacologically useful reagents that can be used to gain insight into the biological functions of HIV-1 MA protein, especially its role(s) in the early, pre-integration stage of the HIV-1 life cycle. Moreover, small molecules identified from this study hold promise as lead compounds for a new class of antiviral agent.
Despite the success of antiretroviral drug regimens, new targets for inhibition of HIV-1 replication are highly desirable, and new drugs are needed to combat the rising problem of drug resistance. The studies proposed in this application will characterize a class of compounds targeted at the HIV-1 matrix (MA) protein and that act via a novel mechanism at multiple stages in the HIV-1 life cycle. The compounds identified within this proposal have the potential to serve as templates for novel anti-HIV agents while also providing reagents with which to dissect the basic biology of HIV-1.
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