UCLA1, a synthetic derivative of a gp120 RNA aptamer, inhibits entry of human immunodeficiency virus type 1 subtype C

Entry of human immunodeficiency virus type 1 (HIV-1) into cells is mediated by the virion surface envelope (Env) glycoproteins, making it a desirable target for antiretroviral entry inhibitors. We previously isolated a family of gp120 binding RNA aptamers and showed that they neutralized the infectivity of HIV-1. In this study, we assessed the activity of a shortened synthetic derivative of the B40 aptamer, called UCLA1, against a large panel of HIV-1 subtype C viruses. UCLA1 tightly bound to a consensus HIV-1 subtype C gp120 and neutralized isolates of the same subtype with 50% inhibitory concentrations (IC(50)s) in the nanomolar range. The aptamer had little toxicity in tests with cell lines and primary cells. Furthermore, it exhibited high therapeutic indices, suggesting that it may be effective at very low doses. Mapping of UCLA1 binding sites on gp120 revealed eight amino acid residues that modulated neutralization resistance. This included residues within the coreceptor binding site, at the base of the V3 loop, and in the bridging sheet within the conserved V1/V2 stem-loop of gp120. The aptamer was also shown to have synergistic effects with T20, a gp41 fusion inhibitor, and IgG1b12 (b12), an anti-CD4 binding site monoclonal antibody. These results suggest that UCLA1 may be suitable for development as a potent HIV-1 entry inhibitor.     

10-Hydroxy-7,8-dihydropyrazino[1',2':1,5]pyrrolo[2,3-d]pyridazine-1,9(2H,6H)-diones: potent, orally bioavailable HIV-1 integrase strand-transfer inhibitors with activity against integrase mutants

A series of 10-hydroxy-7,8-dihydropyrazino[1',2':1,5]pyrrolo[2,3-d]pyridazine-1,9(2H,6H)-diones was synthesized and tested for their inhibition of HIV-1 replication in cell culture. Structure-activity studies indicated that high antiviral potency against wild-type virus as well as viruses containing integrase mutations that confer resistance to three different structural classes of integrase inhibitors could be achieved by incorporation of small aliphatic groups at certain positions on the core template. An optimal compound from this study, 16, inhibits integrase strand-transfer activity with an IC(50) value of 10 nM, inhibits HIV-1 replication in cell culture with an IC(95) value of 35 nM in the presence of 50% normal human serum, and displays modest pharmacokinetic properties in rats (i.v. t(1/2)=5.3 h, F=17%).