Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 21, 2006
Publication Date: August 31, 2006
Citation: Pruett Jr., J.H., Untalan, P.M., Davey, R.B. 2006. Identification and partial purification of serologically defined Boophilus microplus larval antigens by natural ectoparasite exposure. Veterinary Parasitology. 140:148-157. Interpretive Summary: The southern cattle tick, Boophilus microplus, is an important parasite pest of cattle, as it impacts economic production and has the ability to transmit disease from sick cattle to healthy cattle. The southern cattle tick is primarily controlled with chemical pesticides. The tick population has the genetic potential to become resistant or tolerant to these pesticides, reducing the effectiveness of the pesticide. New vaccine control technologies have been commercialized that are based upon tick protein targets that are not exposed to the host by natural exposure. Thus, to be effective these vaccines need to be administered often. Cattle can develop acquired immunological resistance to ticks after repeated exposure. Immune cattle are responding to tick proteins that are exposed to the cow with of natural infestation. In our project, we are attempting to identify tick proteins, of larval, nymphal, and adult life-stages that elicit an antibody response in cattle with natural tick exposure. This report is the first in a series of reports designed to accomplish this task. The current report identifies seven larval proteins that may be specific to southern cattle tick exposure. These proteins may play varied roles in successful tick feeding, and along with their diagnostic potential, may serve as vaccine candidates for control of the tick and the diseases transmitted
Technical Abstract: In an effort to identify life-stage specific Boophilus microplus proteins that elicit a humoral response in cattle, soluble proteins were extracted from 10-14-day-old larvae and subsequently fractionated by size-exclusion chromatography and reverse-phase high pressure liquid chromatography. Several antigens were identified by Western blotting as potentially shared with other ixodid tick species since antibodies to these proteins were present in sera of calves not previously exposed to B. microplus. Six putative B. microplus-specific antigens were identified by antibodies in the sera of calves repeatedly exposed to B. microplus larvae. One of the antigens, a 19.1 kDa protein, was used in the development of a diagnostic kELISA for previous exposure to B. microplus. The 19.1 kDa protein did not have tryptic protease activity or inhibit bovine trypsin activity, but appeared to be allergenic in that a partially pure fraction elicited immediate-type hypersensitivity responses in calves previously exposed to B. microplus. We are obtaining amino acid sequence information for the 19.1 kDa protein as well as an additional prominent B. microplus-specific antigen (98.2 kDa).