Paired receptor signaling for NK cell virus control and antiviral immunity

University Of Virginia, Charlottesville VA

Investigators

Abstract

Project Summary. Viral infections and ensuing diseases are a global threat to human life. Intriguingly, some individuals are at much lower risk of viral infection and life-threatening disease than others, which is explained in part by host diversity. This point is highlighted in the case of rare individuals known as `elite-controllers' who survive HIV infection long- term, exclusive of antiretroviral therapy, and without progressing to AIDS. Many HIV controllers express HLA- B57 and its cognate KIR3DL1 inhibitory receptor which licenses NK cells for increased functionality in these individuals. Though the role of HLA-B57 and KIR3DL1 in antiviral immunity remain unresolved, these findings suggest that 3DL1+ NK cells may be key to long-term survival. By analogy, the H-2Dk class I molecule in mice confers resistance to murine cytomegalovirus (MCMV) infection. We found that licensed NK cells in mice bearing the Dk-binding Ly49G2 inhibitory receptor become selectively activated and rapidly expand during MCMV infection. We also discovered that Ly49G2 together with the Ly49R activating receptor is required in NK cell paired receptor virus control during MCMV infection. Related but distinct Dk-binding Ly49 inhibitory receptors however fail to promote similar virus control. The basis for Ly49 paired receptor virus control is unknown. A broad, long-term objective for this research project is to investigate how NK receptor polymorphism affects antiviral immunity and to delineate the basis of paired receptor virus control. Aim 1 studies the molecular basis for paired receptor signaling in antiviral NK cells during MCMV infection. scCITEseq and Mass Spectroscopic (MS) proteome sequencing will be used to identify NK cell paired receptor signaling pathways for virus control. Key hits associated with paired receptor signaling variations in NK cells lacking one or both Ly49 receptors will be tested in pathway validation studies, and with transgenic approaches designed to test how NK-specific transgenic expression of Ly49 receptors or ablation of signaling adaptors in transgenic primary NK cells affects MCMV susceptibility upon transfer to Ly49G2-deficient mice. Aim 2 investigates the effect of polymorphism on NK paired receptor signaling for MCMV control. A hybrid model will be developed to investigate how polymorphism affects paired receptor virus control. Both NK cell licensing and receptor–ligand binding assays will be used to delineate how Ly49 polymorphism affects NK effector activity and the potential to mediate paired receptor responses during MCMV infection. scCITEseq and MS proteome sequencing will be further used to identify perturbations in paired receptor signaling pathways coinciding with Ly49 polymorphism. Aim 3 tests if polymorphic human NK receptors mediate paired receptor-like responses upon stimulation or exposure to HIV- infected CD4 T cells. Human NK cells with defined KIR–HLA types coinciding with the potential to mediate HIV control will be identified from a pre-existing cohort of 1200 subjects. HLA-B57+ NK cells expressing both 3DL1 and 3DS1 KIRs will be tested for functional licensing and paired receptor-like responses upon exposure to HIV- infected CD4 T cell targets in comparison to donor NK cells expressing only 3DL1 or 3DS1 KIRs.