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.

Public Health Relevance

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.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
Project #
Application #
Study Section
Vaccines Against Microbial Diseases (VMD)
Program Officer
Mukhopadhyay, Suman
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Wisconsin Madison
Schools of Veterinary Medicine
United States
Zip Code
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; GuimarĂ£es, 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

Showing the most recent 10 out of 30 publications