ARS | Publication request: Serologically defined Rhipicephalus (Boophilus) microplus larval antigens in BmLF3, a partially pure Sephacryl S-300 fraction of crude larval proteins

Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 21, 2008
Publication Date: August 17, 2008
Citation: Pruett Jr, J.H., Olafson, P.U., Davey, R.B. 2008. Serologically defined Rhipicephalus (Boophilus) microplus larval antigens in BmLF3, a partially pure Sephacryl S-300 fraction of crude larval proteins. Veterinary Parasitology. 155(3-4):264-272.

Interpretive Summary: The southern cattle tick, Rhipichephalus (Boophilus) microplus, is a parasite pest of cattle capable of transmitting pathogens from sick cattle to healthy cattle. Control of ticks is achieved with chemical acaricides and the ticks have the genetic potential to become resistant or tolerant to these chemicals, reducing their effectiveness. Cattle can develop acquired immunological resistance to ticks after repeated exposure. Immune cattle are responding to tick proteins that are exposed to the cow as a result of natural infestation most likely through salivary gland secretions. In our project, we are attempting to identify tick proteins, of larval, nymphal, and adult life-stages that elicit an antibody response in cattle as a result of natural tick exposure. This report is the second in a series providing a database of potential candidate vaccine antigens and proteins important to tick physiology. In this study, we add 6 common ixodid antigens and 7 R. microplus specific antigens to the database. The database currently contains these serologically defined R. microplus proteins, ixodid shared 15, and R. microplus specific, 13. These proteins may play varied roles in successful tick feeding, and along with their diagnostic potential, may serve as vaccine candidates in the rational design of sustainable strategies for control of the tick and the diseases transmitted.

Technical Abstract: This report is the second in a series providing a database of Rhipicephalus (Boophilus) microplus larval proteins that elicit a humoral immune response in cattle as a result of natural ectoparasite infestation. Larval proteins of R. microplus are complex and the profile is not dominated by any major proteins. Thus, fractionation of these proteins and enhancing lesser moieties is necessary for their study. This report focuses upon a S-300 Sephacryl (molecular sieve) column fraction, fraction 3 (BmLF3). With the use of SDS-PAGE (without-2ME) and Western blotting this fraction was found to contain 6 common ixodid antigens, those potentially shared with other ixodid species, and 8 apparent R. microplus specific antigens. In addition, BmLF3 contains potent inhibitors of trypsin activity. However, these inhibitors of trypsin did not appear to elicit host antibodies as a result of natural ectoparasite exposure, as defined by Western blotting of reduced and denatured trypsin binding proteins purified by affinity chromatography.