Inhibition of the Replication of Clinical Drug-Resistant HIV-1 Strains by Small Molecule Integrase Inhibitors M522 and M532

Abstract

Objective: Integrase (IN) is an enzyme essential for HIV-1 replication that has been a target of antiretroviral drug therapy. Since emerging HIV-1 variants have frequently become clinically resistant to antiretroviral agents, it is necessary to develop alternative IN inhibitors. Methods: We tested IN inhibitors, M522 and M532, against clinically resistant HIV-1 strains to antiretroviral drugs (AZT, non-nucleoside reverse transcriptase inhibitors, IN drug raltegravir, protease inhibitors); wild-type and clinical isolate from HIV-infected patients. We performed disintegration studies to show the interaction of M522 and M532 with the catalytic core domain of HIV-1 IN and time-of-drug-addition experiments to determine the inhibition step of viral replication. We tested selection of HIV-1 with M522 and M532 to examine the emergence of new drug resistant virus. CD4+ cell count was calculated for several groups of cells infected with HIV, cells treated and non-treated with M522 and M532 to evaluate their protective effect. Results: M522 and M532 inhibited the replication of HIV-1 strains (wild-type; drug-resistant; clinical isolate from infected patients; and laboratory strains) with high potency. These inhibitors interacted with the catalytic core domain of HIV-1 IN and blocked its activity, prevented viral integration. M522 and M532 interfered with the viral replication precisely at the integration step. HIV-1 virus did not develop resistance to M522 and M532 for 20 viral passages (160 days). These IN inhibitors protected the infected cells from cytopathic effects and the CD4+ cell counts of these cells treated with M522 and M532 were found to be identical to those of the uninfected cells. Conclusion: M522 and M532 are potent against clinical isolate from HIV-infected patients, wild-type and clinically resistant strains especially the relevant raltegravir-resistant virus. Development of M522 and M532 as new mutationinsensitive drugs aiming for the protection of CD4+ T-cells during HIV infection in the clinical trials is in progress.