ABSTRACT:
AG1776 (formerly JE-2147) is a novel peptidomimetic inhibitor of HIV protease that has demonstrated potent in vitro antiviral activity against clinical isolates and laboratory strains of HIV-1 and -2 with a mean EC50 value of 47.6 nM. In addition, HIV-1 isolates with reduced susceptibility to indinavir, ritonavir, saquinavir and/or nelfinavir and that contain protease amino acid substitutions V82A, G48V/V82A, V82A/L90M, V82F/L90M, I84V/L90M, or D30N remained susceptible to AG1776 as determined by the Antivirogram method. Previous reports from in vitro serial passage studies utilizing HIV-1 strain IIIB propagated in the presence of increasing concentrations of AG1776 have identified HIV variants that demonstrate a 16-fold reduction in susceptibility to AG1776 and that contain protease amino acid substitutions L10F, I47V, and V82I or I84V.
To identify amino acid substitutions that arise in different viral backgrounds and to examine the temporal appearance of these substitutions, HIV-1 strains RF and NL4.3 were each passaged in the presence of increasing concentrations of AG1776. Viral RNA was isolated from culture supernatants, amplified by RT-PCR, and cloned for sequence analysis. An initial HIV-1 RF variant isolated after six passages revealed one substitution at residue 47 (I47V)in 15/15 clones sequenced. Genotypic and phenotypic characterization of variants isolated at later passages is in progress. These results determine the in vitro resistance profile for AG1776, a potentially promising clinical candidate.
