Rickettsia rickettsii is the causative agent of Rocky Mountain spotted fever (RMSF), one of the most severe infectious diseases in the United States. To better understand the molecular mechanisms by which rickettsiae undergo transmission to vertebrate hosts, we will characterize rickettsiae inside the tick vector. Our long term goal is to exploit the differences between rickettsiae of varying pathogenicity and elucidate the mechanisms of rickettsial pathogenesis in ticks in order to develop novel approaches to control tick-borne rickettsial diseases. Towards this objective, we propose to use comparative proteomics to assess the molecular interactions between ticks and tick-borne rickettsiae.
Aims of these studies will characterize the rate at which spotted fever group Rickettsia spread through individual ticks and throughout individual tick tissues, in addition to identifing Rickettsia-derived molecules that are involved in transmission events. Experiments under these aims will identify: 1) differences in species ranging from endosymbionts to pathogens, 2) differences in rickettsial protein expression profiles in various tissues, and 3) conserved and unique antigens recognized by the vertebrate host. Studies will assess proteomes of Rickettsia rickettsii in the salivary glands and ovaries of Dermacentor variabilis ticks by two-dimensional gel electrophoresis. Additionally, antigenic proteins will be identified by immunoblot analysis; candidate proteins will be identified by mass spectrometry. Comparative analysis will include proteomes of rickettsiae not associated with human disease (R. montanensis and R. bellii). By identifying molecules which define the virulence of rickettsiae in arthropods, novel aspects of rickettsial biology will be elucidated and subsequently exploited for control of the pathogen. Rickettsioses are diseases caused by members of the typhus group and spotted fever group of Rickettsia. Pathogenic Rickettsia are typically transmitted to humans by arthropods (insects and ticks). To better understand the mechanisms of rickettsial virulence, this project seeks to examine the interplay between spotted fever group Rickettsia and the vector tick. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21AI070705-02
Application #
7244140
Study Section
Special Emphasis Panel (ZRG1-VB-P (01))
Program Officer
Perdue, Samuel S
Project Start
2006-06-01
Project End
2009-05-31
Budget Start
2007-06-01
Budget End
2009-05-31
Support Year
2
Fiscal Year
2007
Total Cost
$178,421
Indirect Cost
Name
Louisiana State University A&M Col Baton Rouge
Department
Pathology
Type
Schools of Veterinary Medicine
DUNS #
075050765
City
Baton Rouge
State
LA
Country
United States
Zip Code
70803
Pornwiroon, Walairat; Bourchookarn, Apichai; Paddock, Christopher D et al. (2015) Immunoproteomic profiling of Rickettsia parkeri and Rickettsia amblyommii. Ticks Tick Borne Dis 6:829-35
Pornwiroon, Walairat; Bourchookarn, Apichai; Paddock, Christopher D et al. (2009) Proteomic analysis of Rickettsia parkeri strain portsmouth. Infect Immun 77:5262-71
Reif, Kathryn E; Stout, Rhett W; Henry, Gretchen C et al. (2008) Prevalence and infection load dynamics of Rickettsia felis in actively feeding cat fleas. PLoS One 3:e2805
Zanettii, Andre S; Pornwiroon, Walairat; Kearney, Michael T et al. (2008) Characterization of rickettsial infection in Amblyomma americanum (Acari: Ixodidae) by quantitative real-time polymerase chain reaction. J Med Entomol 45:267-75
Sunyakumthorn, Piyanate; Bourchookarn, Apichai; Pornwiroon, Walairat et al. (2008) Characterization and growth of polymorphic Rickettsia felis in a tick cell line. Appl Environ Microbiol 74:3151-8