Amino Acid Substitutions in Gag Protein at Non-cleavage Sites Are Indispensable for the Development of a High Multitude of HIV-1 Resistance against Protease Inhibitors

Decreased Stimulation of CD4+ T Cell Proliferation and IL-2 Production by Highly Enriched Populations of HIV-Infected Dendritic Cells

“…Zidovudine and didanosine (ddI) were purchased from Sigma-Aldrich (St. Louis, MO) and JE2147 was obtained from Japan Energy (Tokyo, Japan). The latter is a relatively new potent protease inhibitor that has been used in previous laboratory studies (24,25). Dr. R. Offord at the University of Geneva (Geneva, Switzerland) kindly provided aminooxypentane (AOP)-RANTES, Dr. N. Fujii at Kyoto University (Kyoto, Japan) kindly provided AMD3100, and Genentech (Vacavill, CA) kindly provided soluble (s) CD4.…”

Altered HIV-1 Gag Protein Interactions with Cyclophilin A (CypA) on the Acquisition of H219Q and H219P Substitutions in the CypA Binding Loop

“…HIV-1 develops resistance mainly by substituting amino acids in the target viral enzyme or component; however, recent studies have revealed that certain polymorphic amino acid residues also contribute to the viral resistance (2,3). We recently found that multiple amino acid substitutions emerged in noncleavage sites of the Gag protein, which were associated with the development of HIV-1 resistance against PIs (4). Among such amino acid substitutions, H219Q, occurring in the cyclophilin A (CypA) binding loop in the p24 Gag protein, conferred the greatest replication advantage on HIV-1 (4).…”

“…We recently found that multiple amino acid substitutions emerged in noncleavage sites of the Gag protein, which were associated with the development of HIV-1 resistance against PIs (4). Among such amino acid substitutions, H219Q, occurring in the cyclophilin A (CypA) binding loop in the p24 Gag protein, conferred the greatest replication advantage on HIV-1 (4). CypA binds to p24 Gag protein, resulting in the packaging of ϳ200 copies of CypA into each HIV-1 virion (5,6), and is thought to perform an essential role early in the HIV-1 replication cycle (7,8), perhaps by destabilizing the capsid (p24 Gag protein) shell during viral entry and uncoating (9) and/or by performing an additional chaperon function, facilitating correct capsid condensation during viral maturation (10,11).…”

Clinical Significance of Human Immunodeficiency Virus Type 1 Replication Fitness

“…These mutations in gag were also essential for the mutant virus' replication in the presence of protease inhibitors. The L75R and H219Q mutations also improved the replication fitness of the wild-type laboratory strain NL4-3 but did not allow replication in the presence of protease inhibitors (68). It is of interest that the H219Q mutation is in the cyclophilin A binding loop and that the replication advantage conferred by it was influenced by the cyclophilin A concentration of different cell types (67), suggesting that gag-cyclophilin A interactions are important for HIV-1 replication fitness.…”

“…Mutations in gag that were not associated with cleavage sites or the PTAPP motif were also observed to accumulate when a laboratory strain was passaged in the presence of escalating concentrations of protease inhibitors (68). Two of these mutations, L75R and H219Q, improved the replication fitness of the protease inhibitor-resistant mutant L10F/V32I/M46I/I54M/A71V/I84V in the absence of drug (68). These mutations in gag were also essential for the mutant virus' replication in the presence of protease inhibitors.…”