The dynamics of HIV-1 replication in vivo are largely unknown yet they are critical to our understanding of disease pathogenesis. Experimental drugs that are potent inhibitors of viral replication can be used to show that the composite lifespan of plasma virus and virus-producing cells is remarkably short (half-life approximately 2 days). Almost complete replacement of wild-type virus in plasma by drug-resistant variants occurs after fourteen days, indicating that HIV-1 viraemia is sustained primarily by a dynamic process involving continuous rounds of de novo virus infection and replication and rapid cell turnover.

Viral dynamics in human immunodeficiency virus type 1 infection

Background The new protease inhibitors are potent inhibitors of the human immunodeficiency virus (HIV), and in combination with other antiretroviral drugs they may be able to cause profound and sustained suppression of HIV replication. Methods In this double-blind study, 97 HIV-infected patients who had received zidovudine treatment for at least 6 months and had 50 to 400 CD4 cells per cubic millimeter and at least 20,000 copies of HIV RNA per milliliter were randomly assigned to one of three treatments for up to 52 weeks: 800 mg of indinavir every eight hours; 200 mg of zidovudine every eight hours combined with 150 mg of lamivudine twice daily; or all three drugs. The patients were followed to monitor the occurrence of adverse events and changes in viral load and CD4 cell counts. Results The decrease in HIV RNA over the first 24 weeks was greater in the three-drug group than in the other groups (P<0.001 for each comparison). RNA levels decreased to less than 500 copies per milliliter at week 24 in 28 of...

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Treatment with Indinavir, Zidovudine, and Lamivudine in Adults with Human Immunodeficiency Virus Infection and Prior Antiretroviral Therapy

INHIBITORS of the human immunodeficiency virus type 1 (HIV-1) protease have entered clinical study as potential therapeutic agents for HIV-1 infection. The clinical efficacy of HIV-1 reverse transcriptase inhibitors has been limited by the emergence of resistant viral variants. Similarly, variants expressing resistance to protease inhibitors have been derived in cell culture1-10. We now report the characterization of resistant variants isolated from patients undergoing therapy with the protease inhibitor MK-639 (formerly designated L-735,524). Five of these variants, isolated from four patients, exhibited cross-resistance to all members of a panel of six structurally diverse protease inhibitors. This suggests that com-bination therapy with multiple protease inhibitors may not prevent loss of antiviral activity resulting from resistance selection. In addition, previous therapy with one compound may abrogate the benefit of subsequent treatment with a second inhibitor.

In vivo emergence of HIV-1 variants resistant to multiple protease inhibitors

Molecular recognition of protein-ligand complexes : applications to drug design

Protease inhibitors: current status and future prospects.

To date, numerous inhibitors of the human immunodeficiency virus type 1 protease have been reported, but few have been studied extensively in humans, primarily as a consequence of poor oral bioavailability in animal models. L-735,524 represents a class of human immunodeficiency virus type 1 protease inhibitors, termed hydroxyaminopentane amides, that incorporate a basic amine into the hydroxyethylene inhibitor backbone. L-735,524 is a potent inhibitor of virus replication in cell culture and inhibits the protease-mediated cleavage of the viral precursor polyproteins that results in the production of noninfectious progeny viral particles. The compound is effective against viruses resistant to reverse transcriptase inhibitors and is synergistically active when used in combination with reverse transcriptase inhibitors. Most importantly, L-735,524 exhibits good oral bioavailability and plasma pharmacokinetic profiles in two species of laboratory animals by using clinically acceptable formulations. Accordingly, the compound was selected for evaluation of safety and pharmacokinetic studies in humans.

https://www.pnas.org/content/pnas/91/9/4096.full.pdf

L-735,524: an orally bioavailable human immunodeficiency virus type 1 protease inhibitor

A series of HIV protease inhibitors possessing a hydroxylaminepentanamide transition state isostere have been developed. Incorporation of a basic amine into the backbone of the L-685,434 (2) series provided antiviral potency combined with a highly improved pharmacokinetic profile in animal models. Guided by molecular modeling and an X-ray crystal structure of the inhibited enzyme complex, we were able to design L-735,524. This compound is potent and competitively inhibits HIV-1 PR and HIV-2 PR with Ki values of 0.52 and 3.3 nM, respectively. It also stops the spread of the HIV-1IIIb-infected MT4 lymphoid cells at concentrations of 25-50 nM. To date, numerous HIV-PR inhibitors have been reported, but few have been studied in humans because they lack acceptable oral bioavailability. L-735,524 is orally bioavailable in three animals models, using clinically acceptable formulations, and is currently in phase II human clinical trials.

L-735,524 : the design of a potent and orally bioavailable HIV protease inhibitor

By tethering of a polar hydrophilic group to the P1 or P1' substituent of a Phe-based hydroxyethylene isostere, the antiviral potency of a series of HIV protease inhibitors was improved. The optimum enhancement of anti-HIV activity was observed with the 4-morpholinylethoxy substituent. The substituent effect is consistent with a model derived from inhibitor docked in the crystal structure of the native enzyme. An X-ray crystal structure of the inhibited enzyme determined to 2.25 A verifies the modeling predictions.

Synthesis and antiviral activity of a series of HIV-1 protease inhibitors with functionality tethered to the P1 or P1' phenyl substituents: X-ray crystal structure assisted design.

A series of glycopeptidemimetics based on the hydroxyethylene Phe-Phe isostere have been synthesized and evaluated for their ability to inhibit the enzyme HIV-1 protease. Incorporation of carbohydrate moieties at the P 2 '-position and elimination of P 3 ' amino acid in our lead compound 1, provided inhibitors with only nanomolar potencies (400-800 nM). However, incorporation of a carbohydrate moiety at the P 3 '-position with branched chain amino acid at the P 2 '-position, resulted in inhibitors with subnanomolar potencies. Within this series, compound 21 was the most potent inhibitor (IC 50 value 0.17 nM). This compound has also shown to block the spread of HIV-1 in T-lymphoid cells at an inhibitor conoentration of 200 nM

J C Quintero

Papers

L-735,524: an orally bioavailable human immunodeficiency virus type 1 protease inhibitor

L-735,524 : the design of a potent and orally bioavailable HIV protease inhibitor

Synthesis and antiviral activity of a series of HIV-1 protease inhibitors with functionality tethered to the P1 or P1' phenyl substituents: X-ray crystal structure assisted design.

HIV-1 protease inhibitors: synthesis and biological evaluation of glycopeptidemimetics.