Blockade of Attachment and Fusion Receptors Inhibits HIV-1 Infection of Human Cervical Tissue

Abstract

Identification of cellular factors involved in HIV-1 entry and transmission at mucosal surfaces is critical for understanding viral pathogenesis and development of effective prevention strategies. Here we describe the evaluation of HIV-1 entry inhibitors for their ability to prevent infection of, and dissemination from, human cervical tissue ex vivo. Blockade of CD4 alone or CCR5 and CXCR4 together inhibited localized mucosal infection. However, simultaneous blockade of CD4 and mannose-binding C-type lectin receptors including dendritic cell–specific intercellular adhesion molecule–grabbing integrin was required to inhibit HIV-1 uptake and dissemination by migratory cells. In contrast, direct targeting of HIV-1 by neutralizing mAb b12 and CD4-IgG2 (PRO-542) blocked both localized infection and viral dissemination pathways. Flow cytometric analysis and immunostaining of migratory cells revealed two major populations, CD3+HLA-DR− and CD3−HLA-DR+ cells, with a significant proportion of the latter also expressing dendritic cell–specific intercellular adhesion molecule–grabbing integrin. Bead depletion studies demonstrated that such HLA-DR+ cells accounted for as much as 90% of HIV-1 dissemination. Additional studies using immature monocyte-derived dendritic cells demonstrated that although mannose-binding C-type lectin receptors and CD4 are the principal receptors for gp120, other mechanisms may account for virus capture. Our identification of the predominant receptors involved in HIV-1 infection and dissemination within human cervical tissue highlight important targets for microbicide development.

A mucosally targeted subunit vaccine candidate eliciting HIV-1 transcytosis-blocking Abs

“…[12][13][14]. In addition to direct targeting of HIV-1 by neutralizing Abs (15), HIV-1 transcytosis can be blocked by disruption of rafts and by Abs against the ELDKWA epitope (7,8,10,11).…”

Cyanovirin-N potently inhibits human immunodeficiency virus type 1 infection in cellular and cervical explant models

“…Cervical explant culture was performed as previously described (Fletcher et al, 2005;Greenhead et al, 2000;Hu et al, 2004). Tissue was obtained from women undergoing planned therapeutic hysterectomy at St George's and Kingston Hospitals (London, UK) with written consent (according to the local research ethics committee).…”

“…The ability of CV-N to prevent infection of the female genital tract was examined using ectocervical explants cultured in a non-polarized manner (Fletcher et al, 2005;Greenhead et al, 2000;Hu et al, 2004). Since R5 viruses predominate in the early stages of HIV-1 infection (Zhu et al, 1993) we selected the isolate HIV-1 BaL for these experiments.…”

“…We have previously shown spontaneous migration of CD4 + dendritic cells (DC) from cervical explant tissue during overnight culture, a population of cells able to bind virus via mannose C-type lectin receptors (MCLR) and/or CD4 (Hu et al, 2004). Migratory cells were harvested from explant cultures (exposed to compound and virus as described above) following overnight culture, washed to eliminate cell-free virus, and cocultured with permissive PM1 T cells.…”

“…These studies expand and build on our early demonstration of compound efficacy in tissue and animal models (Tsai et al, 2004). In this study, we have evaluated multiple aspects of CV-N activity including: the ability to block cell-free and cell-to-cell HIV-1 transmission; its activity in the presence of semen; efficacy in the presence of Candida albicans; and activity in human cervical explant cultures (Fletcher et al, 2005;Greenhead et al, 2000;Hu et al, 2004). The potential mitogenic effects of CV-N have been assessed in peripheral blood mononuclear cell (PBMC) cultures, while the potential induction of inflammation has been assessed by measuring changes in production in a panel of 23 cytokines in both PBMC and cervical tissue explants.…”