Submitted to: World Association for the Advancement of Veterinary Parasitologists
Publication Type: Abstract Only
Publication Acceptance Date: 2/16/2005
Publication Date: 10/1/2005
Citation: Cupp, M.S., Cupp, E.W., Navarre, C.B., Panangala, V.S., Zhang, D., Todd, L.W., Blair, C.E. 2005. Vaccination of cattle with recombinant salivary proteins of horn flies (Haematobia irritans irritans). Proceedings of World Association for the Advancement of Veterinary Parasitologists (WAAVP) 2005. Abstract 94. Interpretive Summary:
Technical Abstract: Adult horn flies are ectoparasites of cattle that require multiple daily bloodmeals for basic nutrition and reproduction. We demonstrated earlier that vaccination of cattle with a recombinant form of an anti-thrombin protein in horn fly saliva, Thrombostasin (TB8), caused a reduction in blood uptake of flies and delayed egg development in females. Further analysis of TS revealed that multiple isoforms exist within both field and laboratory strains of horn flies, with the isoform TS9 predominating in North American populations. Recombinant protein was prepared for TS9 (rTS9) and for another, novel, horn fly salivary protein (rHFX) to test their use in an anti-feeding vaccine for cattle. Sixteen horn fly naive Holstein calves, maintained in a large animal isolation facility, were immunized in groups of four calves each with either ovalbumin (OVA-negative control), rTB9 (positive control), rTS9 or rHFX using Freund's Complete (FCA) and Incomplete adjuvants (FIA) in a prime and 2 or 3 boost regimen. Calf responses to vaccination were evaluated by measuring antibody titers (ELISA) and PBMC proliferation responses to vaccine antigens. Antibody titers varied substantially among calves and tended to be higher in calves immunized with recombinant salivary proteins compared to OVA (HFX is greater than TB8yTS9is greater than OVA). PBMC from control immunized calves exposed to horn fly feeding were suppressed in their proliferation response to Con A in the presence of recombinant salivary antigens whereas proliferation responses to Con A from saliva-immunized calves were enhanced. Vaccination with all three recombinant salivary proteins decreased blood uptake compared to uptake by flies feeding on OVA vaccinated calves. Horn fly mortality increased for flies feeding on salivary protein vaccinated calves and was greatest when calves had rHFX vaccination. Delay in egg development for female flies followed the trend observed for horn fly mortality.