ANAPLASMA MARGINALE, THE MOST PREVALENT VECTOR-BORNE PATHOGEN OF CATTLE WORLDWIDE, RESULTS IN >$300 M IN LOSSES EACH YEAR IN THE US. CURRENTLY, THERE ARE NO LICENSED VACCINES FOR ANAPLASMOSIS, AND CONTROL RELIES ON ANTIBIOTIC TREATMENT OF INFECTED ANIMALS. PREVENTION RELIES ON TICK CONTROL, SUCH AS APPLICATION OF CHEMICAL ACARICIDES WHICH RESULTS IN SELECTION OF ACARICIDE-RESISTANT TICK POPULATIONS, CONTAMINATION OF MEAT AND MILK PRODUCTS, AND IS AN IMPORTANT SOURCE OF ENVIRONMENTAL POLLUTION. ADDITIONAL TOOLS TO CONTROL A. MARGINALE WOULD BENEFIT U.S. AGRICULTURE. THE A. MARGINALE BACTERIUM IS TRANSMITTED BY MANY SPECIES OF TICKS INCLUDING THE ROCKY MOUNTAIN WOOD (RMW) TICK (DERMACENTOR ANDERSONI). WE HAVE IDENTIFIED AN ENDOSYMBIONT (NON-DISEASE-CAUSING BACTERIA THAT LIVE WITHIN A HOST) IN THE RMW TICK AND WHEN THIS ENDOSYMBIONT IS PRESENT IN HIGH LEVELS IN THE TICK, THE PATHOGENIC A. MARGINALE BACTERIA CANNOT ESTABLISH HIGH LEVELS OF INFECTION. IN THIS PROJECT WE WILL SHOW THAT OUR PREVIOUS RESULT IS REPRODUCIBLE BY INTRODUCING THE ENDOSYMBIONT INTO A POPULATION OF RMW TICKS THAT DOESN'T ALREADY HAVE IT AND SHOWING THAT IT IS THE ENDOSYMBIONT THAT AFFECTS THE TICKS ABILITY TO ACQUIRE HIGH LEVELS OF A. MARGINALE. THEN WE WILL DETERMINE WHETHER THE ENDOSYMBIONT POSITIVE TICKS HAVE REDUCED THE CARRIAGE OF A. MARGINALE BELOW THE LEVEL FOR EFFICIENT TRANSMISSION. IF THIS IS THE CASE, THEN JUST BY HAVING TICKS THAT CARRY THE ENDOSYMBIONT COULD REDUCE DISEASE TRANSMISSION.WE PROPOSE TO TEST THE HYPOTHESIS THAT THE TICK MICROBIOME IS A DETERMINANT OF THE EFFICIENCY OF A. MARGINALE TRANSMISSION. WE WILL INTRODUCE R. BELLII INTO A D. ANDERSONI POPULATION LACKING THIS ENDOSYMBIONT, AND SHOW THAT A. MARGINALE REPLICATION IS IMPAIRED IN R. BELLII+ TICKS AS COMPARED TO R. BELLII- TICKS. WE WILL EMPLOY AN ARTIFICIAL TICK FEEDING SYSTEM TO IDENTIFY A. MARGINALE INFECTED TICKS AND THEN DO TRANSMISSION EXPERIMENTS USING SINGLE TICK-CALF PAIRINGS. WE EXPECT THAT R. BELLII+ TICKS WILL HAVE LOWER TRANSMISSION EFFICIENCY THAN R. BELLII- TICKS, DEMONSTRATING THAT THE MICROBIOME AFFECTS VECTOR COMPETENCE. THIS WILL LEAD TO THE DEVELOPMENT OF ENVIRONMENTALLY SUSTAINABLE TRANSMISSION BLOCKING STRATEGIES THAT WILL IMPROVE ANIMAL HEALTH. OUR PROPOSAL DIRECTLY ADDRESSES THE PROGRAM AREA PRIORITIES BY TARGETTING THE MICROBIOME TO REDUCE DISEASE TRANSMISSION.

Washington State University, Pullman WA

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