Objective: The aim of this study was to assess the consequence of sequence variations in HLA-C*03:04-presented HIV-1 p24 Gag epitopes on binding of the inhibitory natural killer (NK) cell receptor KIR2DL2 to HLA-C*03:04.
Design: HIV-1 may possibly evade recognition by KIR+ NK cells through selection of sequence variants that interfere with the interactions of inhibitory killer cell immunoglobulin-like receptors (KIRs) and their target ligands on HIV-1 infected cells. KIR2DL2 is an inhibitory NK cell receptor that binds to a family of HLA-C ligands. Here, we investigated whether HIV-1 encodes for HLA-C*03:04-restricted epitopes that alter KIR2DL2 binding.
Methods: Tapasin-deficient 721.220 cells expressing HLA-C*03:04 were pulsed with overlapping peptides (10mers overlapped by nine amino acids, spanning the entire HIV-1 p24 Gag sequence) to identify peptides that stabilized HLA-C expression. The impact that sequence variation in HLA-C*03:04-binding HIV-1 epitopes has on KIR2DL2 binding and KIR2DL2+ NK cell function was determined using KIR2DL2-Fc constructs and NK cell degranulation assays.
Results: Several novel HLA-C*03:04 binding epitopes were identified within the HIV-1 p24 Gag consensus sequence. Three of these consensus sequence peptides (Gag144–152, Gag163–171 and Gag295–304) enabled binding of KIR2DL2 to HLA-C*03:04 and resulted in inhibition of KIR2DL2+ primary NK cells. Furthermore, naturally occurring minor variants of epitope Gag295–304 enhanced KIR2DL2 binding to HLA-C*03:04.
Conclusion: Our data show that naturally occurring sequence variations within HLA-C*03:04-restricted HIV-1 p24 Gag epitopes can have a significant impact on the binding of inhibitory KIR receptors and primary NK cell function.
aRagon Institute of MGH, MIT, and Harvard, Cambridge, Massachusetts, USA
bExperimental Immunology, Academic Medical Center Amsterdam, Amsterdam, The Netherlands
cDepartment of Microbiology and Immunobiology, Harvard Medical School, Boston
dDivision of Microbiology, New England Primate Research Center, Southborough, Massachusetts, USA
eIrsicaixa AIDS Research Institute – HIVACAT, Autonomous University of Barcelona, Badalona and Institució Catalana de Recerca i Estudis Avancats (ICREA), Barcelona, Spain
fCancer and Inflammation Program, Laboratory of Experimental Immunology, SAIC Frederick, Inc., Frederick National Laboratories for Cancer Research, Frederick, Maryland
gDepartment of Pathology and Laboratory Medicine, University of Wisconsin, Madison, Wisconsin, USA
hLaboratory for Translational Immunology, University Medical Center Utrecht, Utrecht
iCenter for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
jHeinrich-Pette-Institut, Leibniz Institute for Experimental Virology, Hamburg, Germany.
*Nienke H. van Teijlingen and Angelique Hölzemer have contributed equally to the writing of the manuscript.
Correspondence to Marcus Altfeld, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Martinistraße 52, 20251 Hamburg, Germany. Tel: +49 40 48051 221; e-mail: firstname.lastname@example.org
Received 27 August, 2013
Revised 9 March, 2014
Accepted 18 March, 2014
Data in this manuscript have not previously been published. However, the data have in part been presented on a poster at the AIDS Vaccine Conference 2012 (Boston, Massachusetts, USA).
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