Abstract
Anti-HIV chimeric antigen receptors (CARs) promote direct killing of infected cells, thus offering a therapeutic approach aimed at durable suppression of infection emerging from viral reservoirs. CD4-based CARs represent a favored option, since they target the essential conserved primary receptor binding site on the HIV envelope glycoprotein (Env). We have previously shown that adding a second Env-binding moiety, such as the carbohydrate recognition domain of human mannose-binding lectin (MBL) that recognizes the highly conserved oligomannose patch on gp120, increases CAR potency in an in vitro HIV suppression assay; moreover it reduces the undesired capacity for the CD4 of the CAR molecule to act as an entry receptor, thereby rendering CAR-expressing CD8+ T cells susceptible to infection. Here, we further improve the bispecific CD4-MBL CAR by adding a third targeting moiety against a distinct conserved Env determinant, i.e. a polypeptide sequence derived from the N-terminus of the HIV coreceptor CCR5. The trispecific CD4-MBL-R5Nt CAR displays enhanced in vitro anti-HIV potency compared to the CD4-MBL CAR, as well as undetectable HIV entry receptor activity. The high anti-HIV potency of the CD4-MBL-R5Nt CAR, coupled with its all-human composition and absence of immunogenic variable regions associated with antibody-based CARs, offer promise for the trispecific construct in therapeutic approaches seeking durable drug-free HIV remission.
Highlights
The development of antiretroviral therapy (ART) drug regimens represents an exceptional medical achievement that has enabled individuals infected with human immunodeficiency virus (HIV) to remain asymptomatic and lead essentially normal lives (Saag et al, 2018)
In contemplating additional motifs for further chimeric antigen receptors (CARs) enhancement, we considered the N-terminal region of the HIV coreceptor CCR5
The native CCR5 N-terminus contains between 2 and 4 sulfated tyrosine residues at positions 2, 10, 14, 15, which have been shown to be necessary for HIV coreceptor function (Choe and Farzan, 2009)
Summary
The development of antiretroviral therapy (ART) drug regimens represents an exceptional medical achievement that has enabled individuals infected with human immunodeficiency virus (HIV) to remain asymptomatic and lead essentially normal lives (Saag et al, 2018). Drug toxicities, high costs, adherence difficulties, emergence of viral resistance, and challenges to medication accessibility to communities at greatest need represent major burdens for the global HIV population (Mouton et al, 2016) These factors are fueling extensive efforts to develop HIV curative approaches that either eradicate the infection from the body (“sterilizing cure”) or achieve long-term remission by durably suppressing the virus (“functional cure”) (Siliciano and Siliciano, 2016; Davenport et al, 2019; Ndung’u et al, 2019; Peterson and Kiem, 2019). A rare subset of individuals, termed “elite controllers,” are able to naturally maintain virus loads below the level of detection in the absence of ART, thanks in large part to their strong HIV-specific CD8+ T cell responses (Goulder and Deeks, 2018) This has fueled considerable interest in devising approaches to endow HIV-infected subjects with elite-controller-like T cell responses to enable longterm discontinuation of ART without a viral rebound. In this context of durable remission, anti-HIV chimeric antigen receptors (CARs) represent a active area of research (Kuhlmann et al, 2018; Wagner, 2018; Kim et al, 2019; Liu et al, 2019; Mylvaganam et al, 2019)
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