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Increased, Durable B-Cell and ADCC Responses Associated with T-Helper Cell Responses to HIV-1 Envelope in Macaques Vaccinated with gp140 Occluded at the CD4 Receptor Binding Site.

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Bogers, Willy MJM 
Barnett, Susan W 
Oostermeijer, Herman 
Nieuwenhuis, Ivonne G 
Beenhakker, Niels 

Abstract

Strategies are needed to improve the immunogenicity of HIV-1 envelope (Env) antigens (Ag) for more long-lived, efficacious HIV-1 vaccine-induced B-cell responses. HIV-1 Env gp140 (native or uncleaved molecules) or gp120 monomeric proteins elicit relatively poor B-cell responses which are short-lived. We hypothesized that Env engagement of the CD4 receptor on T-helper cells results in anergic effects on T-cell recruitment and consequently a lack of strong, robust, and durable B-memory responses. To test this hypothesis, we occluded the CD4 binding site (CD4bs) of gp140 by stable cross-linking with a 3-kDa CD4 miniprotein mimetic, serving to block ligation of gp140 on CD4+ T cells while preserving CD4-inducible (CDi) neutralizing epitopes targeted by antibody-dependent cellular cytotoxicity (ADCC) effector responses. Importantly, immunization of rhesus macaques consistently gave superior B-cell (P < 0.001) response kinetics and superior ADCC (P < 0.014) in a group receiving the CD4bs-occluded vaccine compared to those of animals immunized with gp140. Of the cytokines examined, Ag-specific interleukin-4 (IL-4) T-helper enzyme-linked immunosorbent spot (ELISpot) assays of the CD4bs-occluded group increased earlier (P = 0.025) during the inductive phase. Importantly, CD4bs-occluded gp140 antigen induced superior B-cell and ADCC responses, and the elevated B-cell responses proved to be remarkably durable, lasting more than 60 weeks postimmunization.IMPORTANCE Attempts to develop HIV vaccines capable of inducing potent and durable B-cell responses have been unsuccessful until now. Antigen-specific B-cell development and affinity maturation occurs in germinal centers in lymphoid follicles through a critical interaction between B cells and T follicular helper cells. The HIV envelope binds the CD4 receptor on T cells as soluble shed antigen or as antigen-antibody complexes, causing impairment in the activation of these specialized CD4-positive T cells. We proposed that CD4-binding impairment is partly responsible for the relatively poor B-cell responses to HIV envelope-based vaccines. To test this hypothesis, we blocked the CD4 binding site of the envelope antigen and compared it to currently used unblocked envelope protein. We found superior and durable B-cell responses in macaques vaccinated with an occluded CD4 binding site on the HIV envelope antigen, demonstrating a potentially important new direction in future design of new HIV vaccines.

Description

Keywords

B-cell responses, CD4 mimetic, CD4 occluded, T-cell responses, human immunodeficiency virus, nonhuman primates, vaccines, AIDS Vaccines, Animals, Antibodies, Neutralizing, Antibody-Dependent Cell Cytotoxicity, B-Lymphocytes, Binding Sites, Antibody, CD4 Antigens, HIV Antibodies, HIV-1, Macaca mulatta, T-Lymphocytes, Helper-Inducer, Vaccination, env Gene Products, Human Immunodeficiency Virus

Journal Title

J Virol

Conference Name

Journal ISSN

0022-538X
1098-5514

Volume Title

91

Publisher

American Society for Microbiology
Sponsorship
Wellcome Trust (091501/Z/10/Z)
Wellcome Trust (via Imperial College London) (P14152)
Isaac Newton Trust (1135(ac))
Bill & Melinda Gates Foundation (via University College London (UCL)) (unknown)
Wellcome Trust NIH