Use of Click-Chemistry to Make Bivalent Antibodies for Redirection of T Cells: Proof of Concept in an In Vitro HIV Model

Abstract

Neutralizing HIV gp120 Ab-coated T cells may play a role in providing cytotoxic targeting of HIV-infected cells and thereby reduce or eliminate the HIV reservoir. Using recombinant DNA methods, bispecific T-cell engager (BiTE) antibodies have been designed and FDA approved for treatment of cancer. In this study, we used a simpler method of production, namely hinge region-specific click-chemistry to form a dual-specific, bivalent BiTE (dbBiTE). This was done by joining an intact (150 kDa) anti-gp120 antibody 3BNC117 in high yield (30- 50%) to an intact (150 kDa) anti-human CD3 (OKT3) antibody. The resultant dbBITE was able to bind to both T cells and HIV gp120-positive HEK cells as shown by flow staining. To assess specific cytotoxic responses against HIV gp120-positive cells, we used the anti-gp120/CD3 dbBITES to coat activated human T cells, derived from PBMCs, after anti-CD3/CD28 activation and IL-2 expansion, and co-incubated them with target cells including HIV Lab strain NL4-3 infected PBMC, or cells expressing HIV gp120 and control cell lines. T cells coated with anti-gp120/CD3 dbBITES showed anti-HIV effect in HIV-infected PBMC at various effector to target ratios ranging from 53% to 27%, as measured by p24 Elisa testing, and showed target specific killing ranging from 96% to 36% killing of gp120-positive HEK cells as measured by incuCyte imaging analysis. This methodology has the potential to be developed into a cellular immunotherapy for HIV/AIDS.

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