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Professor
Animal Health and Biomedical Sciences
Phone: 608-262-3177
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Research Areas
Host-Microbe Interaction and Pathogenesis
Immunology
Research Description
Human brucellosis is characterized by undulating fever, which if untreated,
may result in localization of bacteria in various tissues leading to chronic
disease with serious clinical manifestations. Brucella melitensis, a
facultative intracellular pathogen, is the most frequent cause of human
brucellosis. Several genetic and molecular approaches have been used to
identify genes required for Brucella survival and multiplication in the
intracellular niches of phagocytic as well as non-phagocytic cells. While
several virulence factors have been identified using in vitro models,
because of the complex microenvironment of the host many of these factors
may have little or no in vivo relevance.
Our laboratory is focusing on two active areas of Brucella-host
interactions. First, we have used comparative genomic analysis of Brucella
species whole genomes to identify factors that may be responsible for
differences in host preference and virulence restriction. Using a genomic
microarray of Brucella melitensis, hybridization of genomic DNA from five
different Brucella species revealed ORFs altered in five Brucella species.
These ORFs were often found in clusters (islands) in the B. melitensis
genome. Examination of the genomic context of these islands suggested that
many are horizontally acquired. Deletion of selected genomic islands from
virulent B. melitensis leads to attenuation. Identifying particular genes
within the islands that contribute to the phenotypic change are under active
investigation.
Second, despite progress in mouse models of brucellosis, much remains
unknown regarding dissemination and tissue localization of Brucella during
pathogenesis. We have applied bioluminescent imaging using EZ::TN/lux to
gain greater insight into Brucella pathogenesis to identify the dynamics of
acute and chronic infection in real time. Virulent bioluminescent Brucella
was found to replicate in the salivary glands early following infection
suggesting a previously unknown tissue preference. Establishing a niche in
this region may have relevance in humans where infection can result from
ingestion of few bacteria. Chronic Brucella localization occurs in tail
joints, an infection parallel to osteoarticular brucellosis in humans.
Importantly, bioluminescent imaging can rapidly identify attenuated EZ::TN/lux
mutants in infected mice and can reveal differences in dissemination.
Mutants differing in pathogenesis can define the contribution of Brucella
genes to virulence and tissue localization. We are identifying Brucella
genes that contribute to its unique survival strategies in the mammalian
host. Our approach facilitates identifying virulence determinants that may
control tissue specific replication and may help develop therapeutics to
overcome Brucella-induced chronic debilitating conditions.
Publications
Ko, Jinkyung, Gendron-Fitzpatrick, A., and Splitter, G. A. Susceptibility of
interferon regulatory factor-1 (IRF-1) and interferon consensus sequence
binding protein (ICSBP) deficient mice to brucellosis. Journal of
Immunology, 168:2433-2440, 2002.
Ko, J., Gendron-Fitzpatrick, A, Ficht, T.A. and Splitter, G.A. Virulence
criteria for Brucella abortus strains as determined by interferon regulatory
factor-1 deficient mice. Infection and Immunity,70:7004-7012, 2002.
Jarvis, B. W., Harris, T.H., Qureshi, N. and Splitter, G. Rough LPS from
Brucella abortus and E. coli Differentially activate the same MAP Kinase
signaling pathways for TNFα in RAW 264.7 Macrophage-like Cells. Infection
and Immunity, 70:7165-8, 2002.
Eskra, L., Mathison, A., and Splitter, G. Differential Gene Transcription of
RAW264.7 Macrophages Infected with Brucella abortus, Infection and Immunity,
71:1125-33, 2003.
Qureshi, N. Perera, P.-Y., Shen, J., Zhang, G., Lenschat, A., Splitter, G.,
Morrison, D.C., and Vogel, S.N. The proteasome as a Lipopolysaccharide
-binding protein in macrophages: Differential Effects of Proteasome
Inhibition on Lipopolysaccharide-Induced Signaling Events. Journal of
Immunology
171:1515–1525, 2003.
Rajashekara, G., Glasner, J.D., Glover, D.A., Splitter, G.A. Comparative
whole-genome hybridization reveals genomic islands in Brucella species.
Journal of Bacteriology, 186:5040-5051, 2004.
Baek, S.-H., Rajashekara, G., Splitter, G.A., and Shapleigh, J.P. Phenotypic
and genotypic characterization of Brucella neotomae identifies it as a
partial denitrifier. Journal of Bacteriology, 186:6025-31, 2004.
Rajashekara, G. Glover, D.A., Krepps, M., and Splitter, G.A. Temporal
analysis of pathogenic events in virulent and avirulent Brucella melitensis
infections. Cellular Microbiology, 7:1459-73, 2005.
Rajashekara, G., Glover, D.A., Banai, M., O’Callaghan, D. and Splitter, G.A.
Attenuated bioluminescent Brucella melitensis mutants, GR019 (VirB), GR024 (GalE),
and GR026 (90-91IR) display unique infection patterns and confer protection
in mice. Infection and Immunity, In Press.
Lab Members
Linda Eskra
Jerome Harms
Angie Mathison
Erik Petersen
Gireesh Rajashekara
Qiqi Yu
| Laboratory | Graduate Students | Tenure Faculty |
Comp Bio Sci Graduate
Student Listing |
Comp Bio Sci Faculty
Research Areas |
Immunol 528 |