title: Elevated expression levels of inhibitory receptor programmed death 1 on simian immunodeficiency virus-specific CD8 T cells during chronic infection but not after vaccination.
abstract: Here, we study the temporal expression of the inhibitory receptor programmed death 1 (PD-1) on simian immunodeficiency virus (SIV) Gag-specific T cells following pathogenic SIV infection or following vaccination with a DNA/modified vaccinia virus Ankara (DNA/MVA) vaccine and simian/human immunodeficiency virus (SHIV) challenge in macaques. Following infection, the majority (>95%) of Gag-specific CD8 T cells expressed PD-1, and the level of PD-1 expression per cell increased over time. The level of PD-1 expression in lymph nodes and rectal mucosal tissue, the major sites of virus replication, was higher compared to blood. In vitro blockade of PD-1 resulted in enhanced proliferation of SIV-specific CD8 as well as CD4 T cells. In contrast, following vaccination, the majority of peak effector Gag-specific CD8 T cells expressed low levels of PD-1, and these levels decreased further as the cells differentiated into memory cells. In addition, following SHIV challenge of these vaccinated macaques, the level of PD-1 expression on Gag-specific CD8 T cells correlated positively with plasma viremia. These results demonstrate that SIV-specific CD8 T cells express PD-1 after exposure to antigen but downregulate expression under conditions of antigen clearance and enhance expression under conditions of antigen persistence. They also demonstrate that the level of PD-1 expression per cell rather than the presence or absence of expression plays an important role in regulating CD8 T-cell dysfunction in pathogenic SIV infection. In addition, they demonstrate that similar to HIV infection, the PD-1:PD-1 ligand inhibitory pathway is operational in pathogenic SIV infection, and the macaque/SIV model would be ideal to test the safety and therapeutic benefit of blocking this pathway in vivo.
authors: Vaccine Research Center, Department of Microbiology and Immunology, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA.
authors: Vijayakumar
authors: V
authors: Velu
authors: Sunil
authors: S
authors: Kannanganat
authors: Chris
authors: C
authors: Ibegbu
authors: Lakshmi
authors: L
authors: Chennareddi
authors: Francois
authors: F
authors: Villinger
authors: Gordon J
authors: GJ
authors: Freeman
authors: Rafi
authors: R
authors: Ahmed
authors: Rama Rao
authors: RR
authors: Amara
mesh_terms: D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D015703:Antigens, CD / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D051017:Apoptosis Regulatory Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000821:virology*; D002478:Cells, Cultured; D002908:Chronic Disease; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D015967:Gene Expression Regulation, Viral; D008253:Macaca mulatta; D011971:Receptors, Immunologic / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000276:immunology; D018449:SAIDS Vaccines / Q000008:administration & dosage / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology; D016097:Simian Acquired Immunodeficiency Syndrome / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control; D015302:Simian Immunodeficiency Virus / Q000276:immunology*
chemical_list: D019138:Antibodies, Blocking; D015703:Antigens, CD; D051017:Apoptosis Regulatory Proteins; D018984:Epitopes, T-Lymphocyte; D011971:Receptors, Immunologic; D018449:SAIDS Vaccines