CD8+T cells are significant because they clear intracellular infections;however, subverting these immune cells has implications to long-term infections. We will study how Brucella melitensis, a facultative intracellular bacterium, chronically persists in animals in the presence of an immune response. We hypothesize that low numbers and ineffectual CD8+T cells permit continuing infection. We have found BALB/c mice infected with B. melitensis results in chronic infection lasting >12 months using bioluminescent Brucella. Evaluation of the CD8+T cell memory pool from these mice reveals a failure to maintain the CD8+T cell memory phenotype (LFA1hi, KLRG1lo, and CD127hi), or polyfunctional cytokine expression (IL-2, IFN-? and TNF-?). These findings indicate CD8+T cells express an """"""""exhausted"""""""" phenotype suggesting that Brucella evades this known effector mechanism for removing intracellular pathogens. Further, a Brucella protein, TcpB, can inhibit CD8+T cell killing of Brucella peptide expressing target cells in vivo. Our long-term goal is to understand how the bacteria remain in a chronic state in the presence of an immune response, by investigating the following Aims:
Aim 1 : To determine the CD8+T cell response in BALB/c mice during acute and chronic infection. We will compare the magnitude and effectiveness of CD8+Tcell responses in mice during acute and chronic infection using CD8+Teffector and memory markers, transcription factor expression, cytokine production, and in vivo killing. Impact: We will identify CD8+T cell phenotypic differences between acute and chronic infection and hypothesize an """"""""exhausted"""""""" phenotype and ineffectual CD8+Tcells contribute to chronic brucellosis.
Aim 2 : To determine the protective capacity of Brucella-induced memory CD8+T cells. We will examine the capacity of adoptively transferred CD8+T cells from acute versus chronic infections to protect naive animals from a first infection. Impact: We expect CD8+Tcells from acute infected mice will protect naive mice better than cells from chronically infected mice supporting a loss of functional CD8+Tcells with chronic infection.
Aim 3 : To determine the inhibitory ability of Brucella TcpB on cytotoxic CD8+T cells. We will determine the ability of the TcpB protein to inhibit cytotoxic CD8+T cell killing of infected cells and the kinetics of this inhibition in vivo during infection. Impact: We expect that TcpB protein modulates the adaptive immune response by inhibiting CD8+T cell killing permitting long-term survival of Brucella-infected cells. Our studies represent a critical first step in elucidating how Brucella infection shapes CD8+T cell effector and memory responses. This work will fill a serious void in understanding the role of CD8+T cells in brucellosis that likely participate in the resolution of tis disease.
Brucellosis is a chronic debilitating bacterial disease and a prevalent zoonosis worldwide. CD8+ T cells likely play a critical role in controlling the intracellular infection, but little is known regarding effector and memory responses of these CD8+T cells during infection. We will study how effector and memory CD8+T cells respond in acute versus chronic Brucella infection, and we hypothesize that these studies will identify a decline in functional CD8+T cells as brucellosis transitions from early to late infection. Our findings will provide future opportunities to enhance development and persistence of functional CD8+T cells leading to improved bacterial clearance and designing vaccines that can potentate CD8+T memory cells.
|Harms, Jerome S; Khan, Mike; Hall, Cherisse et al. (2018) Brucella Peptide Cross-Reactive Major Histocompatibility Complex Class I Presentation Activates SIINFEKL-Specific T Cell Receptor-Expressing T Cells. Infect Immun 86:|
|Jakka, Padmaja; Bhargavi, Bindu; Namani, Swapna et al. (2018) Cytoplasmic Linker Protein CLIP170 Negatively Regulates TLR4 Signaling by Targeting the TLR Adaptor Protein TIRAP. J Immunol 200:704-714|
|Costa Franco, Miriam M; Marim, Fernanda; Guimarães, Erika S et al. (2018) Brucella abortus Triggers a cGAS-Independent STING Pathway To Induce Host Protection That Involves Guanylate-Binding Proteins and Inflammasome Activation. J Immunol 200:607-622|
|Smith, Judith A (2018) Regulation of Cytokine Production by the Unfolded Protein Response; Implications for Infection and Autoimmunity. Front Immunol 9:422|
|Smith, Judith A (2018) Brucella Lipopolysaccharide and pathogenicity: The core of the matter. Virulence 9:379-382|
|Kassem, Issmat I; Splitter, Gary A; Miller, Sally et al. (2016) Let There Be Light! Bioluminescent Imaging to Study Bacterial Pathogenesis in Live Animals and Plants. Adv Biochem Eng Biotechnol 154:119-45|
|Case, Elizabeth Di Russo; Smith, Judith A; Ficht, Thomas A et al. (2016) Space: A Final Frontier for Vacuolar Pathogens. Traffic 17:461-74|
|Khan, Mike; Harms, Jerome S; Marim, Fernanda M et al. (2016) The Bacterial Second Messenger Cyclic di-GMP Regulates Brucella Pathogenesis and Leads to Altered Host Immune Response. Infect Immun 84:3458-3470|
|Durward-Diioia, Marina; Harms, Jerome; Khan, Mike et al. (2015) CD8+ T cell exhaustion, suppressed gamma interferon production, and delayed memory response induced by chronic Brucella melitensis infection. Infect Immun 83:4759-71|
|Gourley, Christopher R; Petersen, Erik; Harms, Jerome et al. (2015) Decreased in vivo virulence and altered gene expression by a Brucella melitensis light-sensing histidine kinase mutant. Pathog Dis 73:1-8|
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