title: Effector CD8+ T cells are generated in response to an immunodominant epitope in type III effector YopE during primary Yersinia pseudotuberculosis infection.
abstract: YopE is a virulence factor that is secreted into host cells infected by Yersinia species. The YopE C-terminal domain has GTPase-activating protein (GAP) activity. The YopE N-terminal domain contains an epitope that is an immunodominant CD8(+) T cell antigen during primary infection of C57BL/6 mice with Yersinia pseudotuberculosis. The characteristics of the CD8(+) T cells generated in response to the epitope, which comprises YopE amino acid residues 69 to 77 (YopE(69-77)), and the features of YopE that are important for antigenicity during primary infection, are unknown. Following intravenous infection of naïve C57BL/6 mice with a yopE GAP mutant (the R144A mutant), flow cytometry analysis of splenocytes by tetramer and intracellular cytokine staining over a time course showed that YopE69-77-specific CD8(+) T cells producing gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α) were generated by day 7, with a peak at day 14. In addition, ∼80% of YopE(69-77)-specific CD8(+) T cells were positive for KLRG1, a memory phenotype marker, at day 21. To determine if residues that regulate YopE activity by ubiquitination or membrane localization affect the antigenicity of YopE(69-77), mice were infected with a yopE ubiquitination or membrane localization mutant (the R62K or L55N I59N L63N mutant, respectively). These mutants elicited YopE(69-77)-specific CD8(+) T cells producing IFN-γ and TNF-α with kinetics and magnitudes similar to those of the parental R144A strain, indicating that primary infection primes effector CD8(+) T cells independently of the ubiquitination or membrane localization of YopE. Additionally, at day 7, there was an unexpected positive correlation between the numbers of YopE(69-77)-specific CD8(+) T cells and CD11b(+) cells, but not between the numbers of YopE(69-77)-specific CD8(+) T cells and bacterial cells, in spleens, suggesting that the innate immune response contributes to the immunodominance of YopE(69-77).
authors.affiliation: Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, USA yue.zhang@stonybrook.edu.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, USA.
authors.forename: Patricio
authors.initials: P
authors.lastname: Mena
authors.affiliation: Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, USA.
authors.forename: Galina
authors.initials: G
authors.lastname: Romanov
authors.affiliation: Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, USA.
authors.forename: James B
authors.initials: JB
authors.lastname: Bliska
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D016056:Immunodominant Epitopes / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D014774:Virulence; D015009:Yersinia Infections / Q000276:immunology* / Q000382:microbiology; D015011:Yersinia pseudotuberculosis / Q000276:immunology* / Q000472:pathogenicity
chemical_list: D001425:Bacterial Outer Membrane Proteins; D016056:Immunodominant Epitopes; C063239:yopE protein, Yersinia