HIV-1 Nef-mediated downregulation of CD155 results in viral restriction by KIR2DL5+ NK cells

• DOI: 10.1371/journal.ppat.1010572
• Publication Date: 2022-06-24T17:39:33Z
• Authors: Pia Fittje; Angelique Hœlzemer; Wilfredo F. Garci...; Sarah Vollmers; Annika Niehrs; Kerri Hagemann; Glòria Martrus; Christian Körner; Frank Kirchhoff; Daniel Sauter; Marcus Altfeld
• Keywords: 0301 basic medicine; 570; QH301-705.5; 610; Down-Regulation; HIV Infections; RC581-607; Ligands; Antiviral Agents; 3. Good health; Killer Cells, Natural; 03 medical and health sciences; HIV Seropositivity; HIV-1; Humans; Receptors, Natural Killer Cell; Receptors, Virus; nef Gene Products, Human Immunodeficiency Virus; Immunologic diseases. Allergy; Biology (General); Research Article

Antiviral NK cell activity is regulated through the interaction of activating and inhibitory NK cell receptors with their ligands on infected cells. HLA class I molecules serve as ligands for most killer cell immunoglobulin-like receptors (KIRs), but no HLA class I ligands for the inhibitory NK cell receptor KIR2DL5 have been identified to date. Using a NK cell receptor/ligand screening approach, we observed no strong binding of KIR2DL5 to HLA class I or class II molecules, but confirmed that KIR2DL5 binds to the poliovirus receptor (PVR, CD155). Functional studies using primary human NK cells revealed a significantly decreased degranulation of KIR2DL5+NK cells in response to CD155-expressing target cells. We subsequently investigated the role of KIR2DL5/CD155 interactions in HIV-1 infection, and showed that multiple HIV-1 strains significantly decreased CD155 expression levels on HIV-1-infected primary human CD4+T cells via a Nef-dependent mechanism. Co-culture of NK cells with HIV-1-infected CD4+T cells revealed enhanced anti-viral activity of KIR2DL5+NK cells against wild-type versus Nef-deficient viruses, indicating that HIV-1-mediated downregulation of CD155 renders infected cells more susceptible to recognition by KIR2DL5+NK cells. These data show that CD155 suppresses the antiviral activity of KIR2DL5+NK cells and is downmodulated by HIV-1 Nef protein as potential trade-off counteracting activating NK cell ligands, demonstrating the ability of NK cells to counteract immune escape mechanisms employed by HIV-1.