Synergistic inhibition of protease-inhibitor-resistant HIV type 1 by saquinavir in combination with atazanavir or lopinavir.

BACKGROUND: Double-boosted protease inhibitors (PIs) are under investigation for the treatment of patients who are unable to take nucleoside reverse transcriptase inhibitors because of cross-resistance and/or intolerance. Evidence of synergistic inhibition of wild-type HIV has been reported for saquinavir with atazanavir or lopinavir. METHODS: We investigated the activity of these two combinations against a panel of six site-directed mutant HIV-1 strains and 14 clinically derived recombinant HIV-1 strains presenting a range of PI-resistance profiles. RESULTS: No evidence of synergy was observed against wild-type virus for either combination. The combination of saquinavir and lopinavir showed evidence of synergy against four viruses displaying high-level resistance to lopinavir and low-level resistance to saquinavir. Similarly, evidence of synergy between saquinavir and atazanavir was only observed in two viruses which were more susceptible to saquinavir than to atazanavir. CONCLUSIONS: We hypothesize that differences between the PIs in intracellular protein-binding behaviour or inhibition of drug transporters (P glycoprotein, MDR1 and MDR2) could result in intracellular levels of saquinavir being increased by co-administration with lopinavir or atazanavir. The effect of this increase would be masked in cases involving viruses that were susceptible to atazanavir or lopinavir. In virus resistant to lopinavir or atazanavir but susceptible to saquinavir, the majority of the antiviral effect is due to saquinavir; thus even small increases in intracellular concentration could significantly increase virus inhibition. These results confirm that in vitro synergy can be observed between PIs and suggest that the degree of synergy observed might depend on the resistance profile of the virus.

New HIV-1 replication inhibitors of the styryquinoline class bearing aroyl/acyl groups at the C-7 position: synthesis and biological activity.

Novel variants of HIV-1 replication inhibitors of the styrylquinoline class harboring aroyl/acyl group at the C-7 position have been synthesized. In sharp contrast with styrylquinolines bearing a carboxylic acid group at C-7, these compounds proved to be inactive toward HIV-1 integrase in in vitro assays.

Styrylquinolines, integrase inhibitors acting prior to integration: a new mechanism of action for anti-integrase agents.

We have previously shown that styrylquinolines (SQLs) are integrase inhibitors in vitro. They compete with the long terminal repeat substrate for integrase. Here, we describe the cellular mode of action of these molecules. We show that SQLs do not interfere with virus entry. In fact, concentrations of up to 20 times the 50% inhibitory concentration did not inhibit cell-to-cell fusion or affect the interaction between GP120 and CD4 in vitro. Moreover, the pseudotype of the retrovirus envelope did not affect drug activity. Quantitative reverse transcription PCR experiments showed that SQLs do not inhibit the entry of the genomic RNA. In contrast, the treatment of human immunodeficiency virus type 1-infected cells with SQLs reduced the amount of the late cDNA, suggesting for the first time that integrase targeting molecules may affect the accumulation of DNA during reverse transcription. The cellular target of SQLs was confirmed by the appearance of mutations in the integrase gene when viruses were grown in the presence of increasing concentrations of SQLs. Finally, these mutations led to SQL-resistant viruses when introduced into the wild-type sequence. In contrast, SQLs were fully active against reverse transcriptase inhibitor- and diketo acid-resistant viruses, positioning SQLs as a second group of anti-integrase compounds.

Linker-modified quinoline derivatives targeting HIV-1 integrase: synthesis and biological activity.

A novel series of HIV-1 integrase inhibitors was synthesized and tested in both in vitro and ex vivo assays. These inhibitors are featured by the presence of a quinoline subunit and an ancillary aromatic ring linked by functionalized spacers such as amide, hydrazide, urea and 1-hydroxyprop-1-en-3-one moiety. Amide derivatives are the most promising ones and could serve as leads for further developments.