The differential binding and activity of PRO 2000 against diverse HIV-1 envelopes.

OBJECTIVE: PRO 2000 is a polyanionic microbicide that binds directly to the glycoprotein 120 (gp120) envelope protein to inhibit HIV-1 entry. We studied the breadth of PRO 2000 activity against HIV-1 derived from recently transmitted R5 viruses. We also investigated the interaction of this compound with X4 and R5 HIV-1 envelope glycoproteins using an epitope-mapping strategy. METHODS: The anti-HIV activity of PRO 2000 against subtype B and C Env-pseudotyped viruses was assessed in saline and cervicovaginal lavage fluid. Competitive binding assays were performed with X4 and R5 monomeric and virus-associated gp120. RESULTS: PRO 2000 was found to be active against recently transmitted subtype B and C viruses tested in vitro, however, at 1 microg/mL in saline, activity against subtype C was decreased compared with subtype B. Epitope mapping using anti-V3 region antibodies showed that PRO 2000 binds to the V3 region of monomeric and virus-associated X4 gp120 with a higher affinity than to V3 of R5 gp120. In contrast, the interaction of PRO 2000 with the CD4-binding site was similar for both X4 and R5 monomeric and virus-associated gp120. CONCLUSIONS: PRO 2000 has significant activity against recently transmitted viruses, although some activity is lost at low concentrations. Epitope binding studies suggest that this broad activity is due to direct and indirect interactions with multiple gp120 sites rather than V3 binding alone.

Gonococcal lipooligosaccharide suppresses HIV infection in human primary macrophages through induction of innate immunity.

Gonorrhea often occurs as a coinfection with human immunodeficiency virus (HIV). Lipooligosaccharide (LOS) is a component of the gonococcal outer membrane that induces innate immunity through engagement of Toll-like receptor 4 (TLR4). We investigated the effects that LOS from 5 different strains of Neisseria gonorrhoeae have on HIV infection and on HIV provirus in primary human macrophages. LOS-treated human primary macrophages developed resistance to new HIV infection as well as to HIV provirus. Gonococcal LOS from the 5 strains and lipopolysaccharide (LPS) from Escherichia coli showed no significant difference in their anti-HIV activities. Suppression of HIV provirus resulted from the induction of interferon (IFN)-beta and subsequent activation of signal transducer and activator of transcription 1. Neutralization of IFN-beta , but not IFN-alpha , via antibody significantly reduced the anti-HIV activity induced by LOS and LPS. We conclude that LOS expressed by various strains of N. gonorrhoeae induce specific innate immune responses through TLR4 signaling, resulting in anti-HIV activity in human primary macrophages in vitro.

Dual tropism of HIV-1 envelopes derived from renal tubular epithelial cells of patients with HIV-associated nephropathy.

The phenotype of HIV-1 gp120 envelope derived from renal epithelium and peripheral blood mononuclear cells (PBMC) of patients with HIV-associated nephropathy was investigated in vitro. Chimeric viruses were derived from kidney or blood and used to infect primary CD4+T cells, cell lines expressing single co-receptors and a renal epithelial cell line HPT-1. HIV-1 variants derived from renal epithelium were dual tropic whereas simultaneously derived viruses from PBMC were R5-tropic. Utilization of alternative co-receptors CCR3, BONZO and BOB, also differed.

PRO 2000 gel inhibits HIV and herpes simplex virus infection following vaginal application: a double-blind placebo-controlled trial.

BACKGROUND: Microbicides used to prevent the transmission of human immunodeficiency virus (HIV) are advancing to clinical trials on the basis of activity observed in vitro and in animal models. However, no data demonstrate activity of microbicides after application in humans. This study was designed to determine the antiviral activity in cervicovaginal lavage (CVL) samples collected after intravaginal application of 0.5% PRO 2000 gel (Indevus). METHODS: A randomized, double-blind study was conducted to assess the anti-HIV and anti-herpes simplex virus (HSV) activity of PRO 2000 in CVL samples obtained at screening (48 hours before) and 1 hour after application of study or placebo gel. HeLa cells or human macrophages were inoculated with CVL samples spiked with replication-defective HIV containing a luciferase indicator gene and pseudotyped with an R5 envelope. Human cervical epithelial cells were inoculated with CVL samples and challenged with HSV-2(G), and the virus titer was then determined. RESULTS: CVL samples obtained after application of PRO 2000 gel significantly inhibited HIV and HSV infection by at least 1000-fold, compared with CVL samples obtained at screening (P < .001). There were no differences in cytokine levels between the drug and placebo groups. CONCLUSIONS: PRO 2000 gel (0.5%) is sufficiently bioavailable and retains substantial antiviral activity after intravaginal application. This strategy provides a mechanism for testing the efficacy of a microbicide before embarking on large-scale clinical trials.

Infection of human and non-human cells by a highly fusogenic primary CD4-independent HIV-1 isolate with a truncated envelope cytoplasmic tail.

Truncation of the envelope cytoplasmic tail has enabled FIV, SIV, and some laboratory HIV-1 strains to acquire broader cellular tropism and enhanced fusogenicity. Here we have characterized a primary CD4-independent HIV-1 isolate (92UG046-T8) with a truncated cytoplasmic tail that was able to infect and induce syncytia in primary lymphocytes from human, chimpanzee, and monkey, as well as CD4-negative cell lines from human and monkey. Increased syncytia were also noticeable with 293 cells expressing the cloned envelope from the 92UG046-T8 isolate suggesting envelope-mediated cellular fusion. Except pooled serum from HIV-1-infected individuals, monoclonal anti-envelope antibodies or antibodies/antagonists against CD4, CXCR4, and CCR5 were not able to prevent infection by the 92UG046-T8 isolate. This is the first report showing a primary HIV-1 variant with truncated cytoplasmic tail which is highly fusogenic and can infect a broad range of cells from human and non-human origins. In vivo evolution of similar HIV-1 mutants may have important implications in AIDS pathogenesis.