The objective of this proposal is to improve our understanding of the mechanisms of pathogenesis of tick borne rickettsial pathogens that cause ehrlichiosis and anaplasmosis of humans and animals. These pathogens efficiently utilize a small genome (<1.5 Mb) to evade the immune response and establish persistent infection in the mammalian reservoir host, to colonize and replicate in the tick midgut and salivary glands, and to develop infectivity upon renewed feeding of the tick to effect onward transmission. MSP2 was initially defined in Anaplasma marginale and infections of cattle and ticks with this pathogen provide an excellent model for discovering the mechanisms used to modify the surface proteome. In the prior project period, we identified segmental gene conversion of single expression sites for MSP2, and a related surface paralogue MSP3, as a primary mechanism for generating surface diversity and demonstrated differential expression of operon-encoded proteins between the mammalian host and tick vector. A similar gene conversion mechanism is used by Anaplasma phagocytophilum to express a large repertoire of outer membrane proteins in human patients and studies by others support expression from multiple loci to generate surface diversity. Analysis of the A. marginale genome reveals a complex family of outer membrane protein genes related to msp2. This msp2 superfamily is comprised of 32 paralogues, comprising the two msp2 and msp3 operon-linked expression sites, a single msp4 gene locus, multiple msp2 and msp3 pseudogenes, and other uncharacterized msp2-like paralogues. We hypothesize that differential expression of these paralogues and recombination between them generates diversity in the pathogen surface and provides the ability of organisms to adapt to and persist in different hosts and cellular environments.
The specific aims of the present proposal are: 1] Determine if msp2 superfamily genes are differentially expressed during infection of the mammalian and invertebrate hosts; 2] Determine the operon structure and generation of diversity within msp2 superfamily gene clusters; 3] Identify the mechanisms for differential regulation of the msp2 superfamily proteins in the mammalian and invertebrate hosts; and 4] Compare regulation of expression of msp2 superfamily proteins in A. marginale and A. phagocytophilum.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
2R01AI045580-05
Application #
6681247
Study Section
Special Emphasis Panel (ZRG1-BM-1 (01))
Program Officer
Perdue, Samuel S
Project Start
1999-07-01
Project End
2007-12-31
Budget Start
2003-07-01
Budget End
2003-12-31
Support Year
5
Fiscal Year
2003
Total Cost
$145,572
Indirect Cost
Name
University of Florida
Department
Pathology
Type
Schools of Veterinary Medicine
DUNS #
969663814
City
Gainesville
State
FL
Country
United States
Zip Code
32611
Granquist, Erik G; Stuen, Snorre; Crosby, Liliana et al. (2010) Variant-specific and diminishing immune responses towards the highly variable MSP2(P44) outer membrane protein of Anaplasma phagocytophilum during persistent infection in lambs. Vet Immunol Immunopathol 133:117-24
Wamsley, Heather L; Barbet, Anthony F (2008) In situ detection of Anaplasma spp. by DNA target-primed rolling-circle amplification of a padlock probe and intracellular colocalization with immunofluorescently labeled host cell von Willebrand factor. J Clin Microbiol 46:2314-9
Granquist, Erik G; Stuen, Snorre; Lundgren, Anna M et al. (2008) Outer membrane protein sequence variation in lambs experimentally infected with Anaplasma phagocytophilum. Infect Immun 76:120-6
Palmer, Guy H; Futse, James E; Knowles Jr, Donald P et al. (2006) Insights into mechanisms of bacterial antigenic variation derived from the complete genome sequence of Anaplasma marginale. Ann N Y Acad Sci 1078:15-25
Barbet, Anthony F; Lundgren, Anna M; Alleman, A Rick et al. (2006) Structure of the expression site reveals global diversity in MSP2 (P44) variants in Anaplasma phagocytophilum. Infect Immun 74:6429-37
Noh, Susan M; Brayton, Kelly A; Knowles, Donald P et al. (2006) Differential expression and sequence conservation of the Anaplasma marginale msp2 gene superfamily outer membrane proteins. Infect Immun 74:3471-9
Brayton, Kelly A; Kappmeyer, Lowell S; Herndon, David R et al. (2005) Complete genome sequencing of Anaplasma marginale reveals that the surface is skewed to two superfamilies of outer membrane proteins. Proc Natl Acad Sci U S A 102:844-9
Rodriguez, Jose-Luis; Palmer, Guy H; Knowles Jr, Donald P et al. (2005) Distinctly different msp2 pseudogene repertoires in Anaplasma marginale strains that are capable of superinfection. Gene 361:127-32
Zika, Eleni; Fauquier, Lucas; Vandel, Laurence et al. (2005) Interplay among coactivator-associated arginine methyltransferase 1, CBP, and CIITA in IFN-gamma-inducible MHC-II gene expression. Proc Natl Acad Sci U S A 102:16321-6
Brown, Wendy C; Palmer, Guy H; Brayton, Kelly A et al. (2004) CD4+ T lymphocytes from Anaplasma marginale major surface protein 2 (MSP2) vaccinees recognize naturally processed epitopes conserved in MSP3. Infect Immun 72:3688-92

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