title: Novel CD4-Based Bispecific Chimeric Antigen Receptor Designed for Enhanced Anti-HIV Potency and Absence of HIV Entry Receptor Activity.
abstract: Adoptive transfer of CD8 T cells genetically engineered to express "chimeric antigen receptors" (CARs) represents a potential approach toward an HIV infection "functional cure" whereby durable virologic suppression is sustained after discontinuation of antiretroviral therapy. We describe a novel bispecific CAR in which a CD4 segment is linked to a single-chain variable fragment of the 17b human monoclonal antibody recognizing a highly conserved CD4-induced epitope on gp120 involved in coreceptor binding. We compared a standard CD4 CAR with CD4-17b CARs where the polypeptide linker between the CD4 and 17b moieties is sufficiently long (CD4-35-17b CAR) versus too short (CD4-10-17b) to permit simultaneous binding of the two moieties to a single gp120 subunit. When transduced into a peripheral blood mononuclear cell (PBMC) or T cells thereof, all three CD4-based CARs displayed specific functional activities against HIV-1 Env-expressing target cells, including stimulation of gamma interferon (IFN-γ) release, specific target cell killing, and suppression of HIV-1 pseudovirus production. In assays of spreading infection of PBMCs with genetically diverse HIV-1 primary isolates, the CD4-10-17b CAR displayed enhanced potency compared to the CD4 CAR whereas the CD4-35-17b CAR displayed diminished potency. Importantly, both CD4-17b CARs were devoid of a major undesired activity observed with the CD4 CAR, namely, rendering the transduced CD8(+) T cells susceptible to HIV-1 infection. Likely mechanisms for the superior potency of the CD4-10-17b CAR over the CD4-35-17b CAR include the greater potential of the former to engage in the serial antigen binding required for efficient T cell activation and the ability of two CD4-10-17b molecules to simultaneously bind a single gp120 subunit.
  
  
  OBJECTIVE
  HIV research has been energized by prospects for a cure for HIV infection or, at least, for a "functional cure" whereby antiretroviral therapy can be discontinued without virus rebound. This report describes a novel CD4-based "chimeric antigen receptor" (CAR) which, when genetically engineered into T cells, gives them the capability to selectively respond to and kill HIV-infected cells. This CAR displays enhanced features compared to previously described CD4-based CARs, namely, increased potency and avoidance of the undesired rendering of the genetically modified CD8 T cells susceptible to HIV infection. When adoptively transferred back to the individual, the genetically modified T cells will hopefully provide durable killing of infected cells and sustained virus suppression without continued antiretroviral therapy, i.e., a functional cure.
authors: Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
authors: Li
authors: L
authors: Liu
authors: Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
authors: Bhavik
authors: B
authors: Patel
authors: Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
authors: Mustafa H
authors: MH
authors: Ghanem
authors: Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
authors: Virgilio
authors: V
authors: Bundoc
authors: Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors: Zhili
authors: Z
authors: Zheng
authors: Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors: Richard A
authors: RA
authors: Morgan
authors: Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors: Steven A
authors: SA
authors: Rosenberg
authors: Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
authors: Barna
authors: B
authors: Dey
authors: Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA edward_berger@nih.gov.
authors: Edward A
authors: EA
authors: Berger
mesh_terms: D019380:Anti-HIV Agents / Q000378:metabolism*; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000378:metabolism; D015704:CD4 Antigens / Q000235:genetics / Q000378:metabolism; D015483:HIV Antibodies / Q000235:genetics / Q000378:metabolism; D015699:HIV Envelope Protein gp120 / Q000378:metabolism; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology* / Q000821:virology*; D011485:Protein Binding; D011946:Receptors, Antigen / Q000235:genetics / Q000378:metabolism*; D015728:Receptors, HIV / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D057127:Single-Chain Antibodies / Q000235:genetics / Q000378:metabolism; D014161:Transduction, Genetic
chemical_list: D019380:Anti-HIV Agents; D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D011946:Receptors, Antigen; D015728:Receptors, HIV; D011993:Recombinant Fusion Proteins; D057127:Single-Chain Antibodies; C514793:gp120 protein, Human immunodeficiency virus 1