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Pharmacological and Immunologic Interventions Against Vector-Borne Bovine and Equine Babesiosis


Objective 1: Improve control of bovine babesiosis and its tick vector through the identification of novel targets and development of new vaccine strategies. Sub-objective 1A: Identify surface exposed antigens expressed by Babesia bovis during its development within the tick. Sub-objective 1B: Test if antibody response in cattle immunized with tick midgut surface antigens enhances access of bovine antibodies to tick hemolymph. Sub-objective 1C: Determine if immunization with Babesia tick stage and midgut antigens blocks B. bovis transmission.

Objective 2: Evaluate the risks of B. equi or B. caballi transmission by species of ticks indigenous to the United States. Sub-objective 2A: Identify tick species feeding on horses at the outbreak ranch in Texas that are capable of transmitting B. equi. Sub-objective 2B: Determine the B. equi transmission efficiency of vector-competent tick species from the outbreak ranch in Texas.

Objective 3: Determine the impact of both new and current chemotherapeutic agents on the clearance of B. equi or B. caballi from persistently infected horses and on the risks of transmission. Sub-objective 3A: Assess the efficacy of imidocarb dipropionate to eliminate B. equi infection Sub-objective 3B: Develop a serological method that rapidly and accurately predicts elimination of B. equi infection following treatment. Sub-objective 3C: Assess tick-borne transmission risk of imidocarb dipropionate treated horses.

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The discovery of chemical (acaricide) resistant ticks capable of transmitting protozoan parasites that cause bovine babesiosis and the reemergence of equine babesiosis within the United States are the catalysts for this research plan. National concerns are eradication of the currently emerging equine babesiosis, the possibility of reemergence of bovine babesiosis and the need for novel methods to control the causal parasites and their tick vectors. The current strategy in the U.S. for bovine babesiosis is control of ticks through acaricides. However, the development of ticks resistant to acaricides is resulting in geographic expansion of these vectors in the U.S. Since cattle entry is not monitored by serology, infected cattle are entering the U.S. The risk of bovine babesiosis is significantly increased by the presence and expanding range of ticks capable of transmission and the lack of serologic monitoring of cattle. To protect the U.S. cattle population from babesiosis, this research plan proposes to develop novel immunological interventions and to use these tools to test the hypothesis that tick transmission of Babesia bovis can be blocked. The primary goal is to disrupt the B. bovis-tick interface at the level of the tick midgut and hemolymph. In contrast to bovine babesiosis, the control strategy for equine babesiosis is based on serological restriction of infected horses from entering the country. Due to previous use of the complement fixation test (CFT), which lacked sensitivity, infected horses have been admitted into the U.S. which likely led, at least in part, to the recent reemergence of this foreign equine disease in the U.S. The goal of this research plan related to equine babesiosis is to assist the Animal Plant Health Inspection Service (APHIS), State Veterinarians and owners in eliminating Babesia infections, transmission risk, and potential endemicity by developing pharmacological interventions. Replacing 5348-32000-028-00D (October 2011).
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Kappmeyer, Lowell
Knowles, Donald
Scoles, Glen
Suarez, Carlos
Ueti, Massaro
Published Journal Articles USDA ARS (NP 108):
Targeted surface expression of an exogenous antigen in stably transfected Babesia bovis
Laughery JM, Knowles DP, Schneider DA, Bastos RG, McElwain TF, Suarez CE.
PLoS One. 2014 May 19;9(5):e97890.
The glycosylphosphatidylinositol-anchored protein repertoire of Babesia bovis and its significance for erythrocyte invasion
Rodriguez AE, Florin-Christensen M, Flores DA, Echaide I, Suarez CE, Schnittger L.
Ticks Tick Borne Dis. 2014 Apr;5(3):343-8.
Amblyomma cajennense is an intrastadial biological vector of Theileria equi
Scoles GA, Ueti MW.
Parasit Vectors. 2013 Oct 23;6:306.
Lymphocytes and macrophages are infected by theileria equi, but T cells and B cells are not required to establish infection in vivo
Ramsay JD, Ueti MW, Johnson WC, Scoles GA, Knowles DP, Mealey RH.
PLoS One. 2013 Oct 7;8(10):e76996.
Differential expression of three members of the multidomain adhesion CCp family in babesia bigemina, babesia bovis and theileria equi
Bastos R, Suarez CE, Laughery J, Johnson WC, Ueti MW, Knowles Jr DP .
PLoS One. 2013 Jul 3;8(7):e67765.
Efficacy of imidocarb dipropionate in eliminating Theileria equi from experimentally infected horses
Grause JF, Ueti MW, Nelson JT, Knowles DP, Kappmeyer LS, Bunn TO.
Vet J. 2013 Jun;196(3):541-6.
Diagnosis of Theileria equi infections in horses in the Azores using cELISA and nested PCR
Baptista C, Lopes MS, Tavares AC, Rojer H, Kappmeyer L, Mendonça D, da Câmara Machado A.
Ticks Tick Borne Dis. 2013 Apr;4(3):242-5.
Repertoire of Theileria equi immunodominant antigens bound by equine antibody
Silva MG, Graça T, Suarez CE, Knowles DP.
Mol Biochem Parasitol. 2013 Apr;188(2):109-15.
Genetic characterization of Theileria equi infecting horses in North America: evidence for a limited source of U.S. introductions
Hall CM, Busch JD, Scoles GA, Palma-Cagle KA, Ueti MW, Kappmeyer LS, Wagner DM.
Parasit Vectors. 2013 Feb 11;6:35.
Comparative genomic analysis and phylogenetic position of Theileria equi
Kappmeyer LS, Thiagarajan M, Herndon DR, Ramsay JD, Caler E, Djikeng A, Gillespie JJ, Lau AO, Roalson EH, Silva JC, Silva MG, Suarez CE, Ueti MW, Nene VM, Mealey RH, Knowles DP, Brayton KA.
BMC Genomics. 2012 Nov 9;13:603.
Acute and persistent infection by a transfected Mo7 strain of Babesia bovis
Suarez CE, Laughery JM, Schneider DA, Sondgeroth KS, McElwain TF.
Mol Biochem Parasitol. 2012 Sep;185(1):52-7.
In vitro activity of ponazuril against Theileria equi
Wise LN, Ueti MW, Kappmeyer LS, Hines MT, White SN, Davis W, Knowles DP.
Vet Parasitol. 2012 Apr 30;185(2):282-5.
Re-emergence of the apicomplexan Theileria equi in the United States: elimination of persistent infection and transmission risk
Ueti MW, Mealey RH, Kappmeyer LS, White SN, Kumpula-McWhirter N, Pelzel AM, Grause JF, Bunn TO, Schwartz A, Traub-Dargatz JL, Hendrickson A, Espy B, Guthrie AJ, Fowler WK, Knowles DP.
PLoS One. 2012;7(9):e44713.
Food Safety Categories:
On-Farm Food Safety
Pathogen Biology
Risk Assessment
Farm-to-Table Categories:
On-farm food production