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1st International Workshop on HIV Drug Resistance & Treatment Strategies25-28 June 1997, St. Petersburg, Florida, USA |
IDENTIFICATION AND CHARACTERIZATION OF NOVEL INHIBITORS OF HIV-1 INTEGRASE
Antiviral Therapy 1997;2 (Suppl 5):3 (abstract no. 5)
DJ Hazuda, AL Wolfe, PJ Felock, JC Hastings, C Uncapher Blau, WA Schleif and MD Miller
Department of Antiviral Research, Merck Research Laboratories, West Point, PA 19486, USA
Integrase is the only viral protein known to be required for the multi-step process of integration. These steps include (1) assembly (interaction with specific sequences in the viral LTRs); (2) 3´-end processing (removal of the terminal two bases from each 3´ end of the viral DNA); and (3) strand transfer (transfer of the 3´ viral DNA ends into host cell target DNA). Our efforts to discover inhibitors of HIV-1 integrase have focused on screening defined chemicals and natural products using a novel microtitre plate assay sensitive to inhibitors of assembly as well as to inhibitors of either of the two catalytic activities. This in vitro assay recapitulates the staged reaction which occurs in vivo and can be used to uncouple assembly and catalysis, thus facilitating the characterization of inhibitors.
Screening of several hundred-thousand samples resulted in the elucidation of a variety of structurally diverse compounds; however, upon further characterization, the majority of these inhibitors were determined to affect the binding of integrase to the viral DNA substrate (assembly), but had no effect on either of the subsequent catalytic reactions. Most of these inhibitors were phenolic compounds similar to integrase inhibitors described by other investigators. Consistent with the observation that such inhibitors affect only assembly, these phenolic compounds are poorly active in reactions catalysed by pre-assembled pre-integration complexes isolated from HIV-1-infected cells. The assay was therefore reformatted to specifically identify inhibitors which have activity post-assembly and are therefore likely to affect HIV-1 pre-integration complexes in vivo. Using this assay, we have recently identified several novel inhibitors of HIV-1 integrase. These compounds are structurally and mechanistically distinct from the phenolic inhibitors of integrase and are the first compounds identified which inhibit the catalytic activity of integrase subsequent to assembly. Unlike previously described integrase inhibitors, many of these compounds have comparable activity against recombinant integrase and HIV-1 pre-integration complexes in vitro.
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1997-06-25
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