Mapping of species-specific determinants enabling the induction of MHC-E and MHC-II-restricted CD8+ T cells by cytomegalovirus 4406

Abstract Description Infection of rhesus macaques (RM) with rhesus cytomegalovirus (RhCMV) elicits MHC-I restricted CD8 T cell responses whereas RhCMV deleted for homologs of HCMV UL128, UL130 and UL146 induces MHC-II and MHC-E restricted CD8 T cells. MHC-E restricted T cells are required for RhCMV-based SIV vaccines to provide “control and clear” protection against highly virulent SIV. Vaccination of Mauritian cynomolgus macaques (MCM) with similarly modified Cynomolgus (Cy)CMV/SIV vectors elicited MHC-E-restricted T cells and protected against SIV challenge. In contrast, immunization of RM with CyCMV or MCM with RhCMV failed to elicit MHC-E-restricted T cells suggesting species specificity of CMV-mediated T cell programming. To determine the viral determinants of this species specificity we generated RhCMV/CyCMV chimeras using transformation-associated recombination cloning in yeast. RhCMV and CyCMV genomes were cloned as overlapping fragments that were assembled into quarter genomes by homologous recombination using yeast artificial chromosomes. Quarter genomes were then assembled as four chimeras consisting of three quarters of RhCMV and one quarter of CyCMV. The resulting recombinants were transferred into E. coli and recombinant vectors were recovered in primary rhesus fibroblasts. Analysis of the T cell responses to recombinant Cy/RhCMV chimeras in RM and MCM revealed that a single genomic region, and possibly a single RhCMV gene, is required for unconventional CD8 T cell induction. Funding Sources RO1 AI095113, R37 AI054292, U19 AI128741, P01 AI174856, R01 AI059457, R01 AI175459, R01 AI140888, R01 AI129703, P51OD011092 Topic Categories Viral Immunology (VIR)