Work

27 HIV-associated gastrointestinal microbial dysbiosis influences the efficacy of anti-HIV immunity by immune checkpoint blockade

Year: 2017

Type: article

Abstract: human moiety that recognizes a separate highly conserved site on Env.The second moiety enhances potency and also prevents the CD4 from acting as an entry receptor into CAR-expressing CD8 + T cells.Methods: We previously reported potent and broad activity of a CD4-based bispecific CAR containing an scFv directed against a highly conserved CD4-induced epitope within the coreceptor-binding region of gp120 (Liu et al.J Virol.2015).However, we are concerned that the scFv variable regions would elicit anti-idiotypic immune responses.We therefore designed bispecifc CD4-based CARs wherein the second moiety is the carbohydrate-recognition domain of a human C-type lectin, which recognizes the oligomannose patch obligatorily displayed on gp120 of all clinical HIV-1 variants.Results: Particularly favorable results were obtained with a CAR based on human serum mannose binding lectin (MBL).The CD4-MBL CAR (Fig. A) displayed extremely potent activity against all tested clinical isolates from genetically diverse clades.In spreading infection assays, virus replication was fully suppressed, with p24 release below detection over 2 weeks (suppression 4-5 logs) (Fig. B).The potency of the bispecific CD4-MBL CAR significantly exceeded that of the corresponding monospecific CD4 CAR; moreover, the lectin component fully blocked the entry receptor activity of the CD4 moiety.Conclusions: Mechanistic nvestigations regarding the extreme potency of the bispecific CARs are underway.Studies with inducible Env indicate that CAR killing occurs with targets displaying surface Env levels below detection by flow cytometry.Moreover, the markedly superior suppression of spreading infection by CAR-T cells compared to a targeted immunotoxin suggest kinetic advantages associated with 'killing from the outside'.Preliminary experiments with replicationincompetent pseudoviruses have led us to analyze whether CAR-T cells can kill targets by recognizing Env molecules introduced by incoming virions, prior to synthesis of new Env.These findings support advancing the CD4-MBL CAR into collaborative preclinical studies in relevant animal models.

Source: Journal of Virus Eradication

DOI: 10.1016/s2055-6640(20)30732-9