CD4-mimetic sulfopeptide conjugates display sub-nanomolar anti-HIV-1 activity and protect macaques against a SHIV162P3 vaginal challenge

Abstract

The CD4 and the cryptic coreceptor binding sites of the HIV-1 envelope glycoprotein are key to viral attachment and entry. We developed new molecules comprising a CD4 mimetic peptide linked to anionic compounds (mCD4.1-HS12 and mCD4.1-PS1), that block the CD4-gp120 interaction and simultaneously induce the exposure of the cryptic coreceptor binding site, rendering it accessible to HS12- or PS1- mediated inhibition. Using a cynomolgus macaque model of vaginal challenge with SHIV162P3, we report that mCD4.1-PS1, formulated into a hydroxyethyl-cellulose gel provides 83% protection (5/6 animals). We next engineered the mCD4 moiety of the compound, giving rise to mCD4.2 and mCD4.3 that, when conjugated to PS1, inhibited cell-free and cell-associated HIV-1 with particularly low IC50, in the nM to pM range, including some viral strains that were resistant to the parent molecule mCD4.1. These chemically defined molecules, which target major sites of vulnerability of gp120, are stable for at least 48 hours in conditions replicating the vaginal milieu (37 °C, pH 4.5). They efficiently mimic several large gp120 ligands, including CD4, coreceptor or neutralizing antibodies, to which their efficacy compares very favorably, despite a molecular mass reduced to 5500 Da. Together, these results support the development of such molecules as potential microbicides.

Lack of ADCC Breadth of Human Nonneutralizing Anti-HIV-1 Antibodies

“…We thus examined the effect of mCD4.2-PS1 on the binding and ADCC activity of our panel of nnAbs and bNAbs. mCD4.2-PS1 is a recently described CD4-mimetic sulfopeptide conjugate that binds to HIV-1 Env and inhibits cell-free and cell-associated HIV-1 with particularly low 50% inhibitory concentrations (IC 50 s), in the picomolar-to-nanomolar range (80). mCD4.2-PS1 binds gp120 through its mCD4 moiety and induces the structural modifications necessary to expose the coreceptor binding domain, which, as a result, becomes available to be blocked by the PS1 moiety (81).…”

“…Antibodies were purified by batch/gravity-flow affinity chromatography using protein G-Sepharose 4 fast-flow beads (GE Healthcare). The CD4 mimetic (mCD4.2-PS1) was prepared by chemical synthesis and characterized as previously described (80).…”

In Vivo Modulation of Cervicovaginal Drug Transporters and Tissue Distribution by Film-Released Tenofovir and Darunavir for Topical Prevention of HIV-1

“…In addition, expression analyses in vitro do not mimic closely the complexity of the physiological environment of the cervicovaginal tract where expression of drug transporters may be influenced by pH variations, hormones, mucus, microbiota, and anti- and pro-inflammatory mediators. For the first time, to the best of our knowledge, we provide a comprehensive description of drug transporter expression in the female genital tract of the cynomolgus macaquea common nonhuman primate model for HIV transmission. − …”

Antibody Functional Assays as Measures of Fc Receptor-Mediated Immunity to HIV - New Technologies and their Impact on the HIV Vaccine Field

“…This has been suggested to be a potential vaccine candidate for eliciting CD4i focused antibody responses but will first require an evaluation of the importance of off target killing of uninfected bystander cells to determine if this approach will be effective. Here the multiple effects of small CD4 mimetic compounds, themselves highly potent inhibitors of infection [ 137 ], may prove useful for redeeming CD4i ADCC by redirecting it to killing infected targets. First, these act with co-receptor binding site Abs to reveal CD4i epitopes on the unliganded Env to make infected cells ADCC targets [ 138 ].…”