There is a need to develop improved methods to treat and potentially cure HIV infection. During chronic HIV infection, replication is concentrated within T follicular helper cells (Tfh) located within B cell follicles, where low levels of virus-specific CTL permit ongoing viral replication. We previously showed that elevated levels of simian immunodeficiency virus (SIV)-specific CTL in B cell follicles are linked to both decreased levels of viral replication in follicles and decreased plasma viral loads. These findings provide the rationale to develop a strategy for targeting follicular viral-producing (Tfh) cells using antiviral chimeric antigen receptor (CAR) T cells co-expressing the follicular homing chemokine receptor CXCR5. We hypothesize that antiviral CAR/CXCR5-expressing T cells, when infused into an SIV-infected animal or an HIV-infected individual, will home to B cell follicles, suppress viral replication, and lead to long-term durable remission of SIV and HIV. To begin to test this hypothesis, we engineered gammaretroviral transduction vectors for co-expression of a bispecific anti-SIV CAR and rhesus macaque CXCR5. Viral suppression by CAR/CXCR5-transduced T cells was measured in vitro, and CXCR5-mediated migration was evaluated using both an in vitro transwell migration assay, as well as a novel ex vivo tissue migration assay. The functionality of the CAR/CXCR5 T cells was demonstrated through their potent suppression of SIVmac239 and SIVE660 replication in in vitro and migration to the ligand CXCL13 in vitro, and concentration in B cell follicles in tissues ex vivo. These novel antiviral immunotherapy products have the potential to provide long-term durable remission (functional cure) of HIV and SIV infections.
Bibliographical noteFunding Information:
The authors thank Ms. Chi Phan at the University of Minnesota, and Dr. Martin Wohlfart at the Fred Hutch Viral Vector Core for assistance with viral production, Ms. Kim Weisgrau at the University of Wisconsin-Madison for isolating PBMCs and enriching CD8+ T cells, Dr. Virgilio Bundoc at NIAID for technical support with the CAR-mediated virus suppression assays, and Dr. Brian Fife at the University of Minnesota for assistance in developing the ex vivo migration assay. The authors also thank Dr. GeoffHart at the University of Minnesota for assistance with flow cytometry, Dr. Aaron Rendahl at the University of Minnesota for assistance with statistical analysis, Dr. David N. Levy at New York University for technical guidance, and Dr. Matthew Bronnimann and Ms. Joy Folkvord at the University of Arizona for critical review of this manuscript. Anti-CD3 and anti-CD28 used in these studies were provided by the NIH Nonhuman Primate Reagent Resource (R24 OD010976, U24 AI126683). This study was supported by NIH grants 5R01AI096966-06S1 (PS, EC, and EB), 1UM1AI26617 (PS, EC, and EB), P51OD011106/P51RR000167 (ER), MN-REACH grant 5U01HL127479-03 (PS), and NIH-T32 DA007097 (GM), as well as by funds provided by the NIAID Division of Intramural Research and the NIH Intramural AIDS Targeted Antiviral Program.
- B cell follicles
- CAR-T cells
- CD8 T cells
- Chimeric antigen receptor
- HIV cure strategies
- Simian immunodeficiency virus