Progress 09/01/06 to 08/31/07
Outputs
OUTPUTS: The common cattle Horn Fly, Haematobia irritans, is a hematophagous pest that occurs worldwide. Estimated health and production losses resulting from Horn Fly feeding on cattle in North America approach one billion dollars per year. This project addresses the critical needs for developing immunologic methods to control horn flies. Anti-feeding vaccines for blood-feeding flies are attractive because of ease of administration, specificity for the target species, longevity of effect, and environmental acceptability. Previous research at Auburn University has demonstrated "proof of concept" for the efficacy of salivary proteins as antigens for a horn fly vaccine and resulted in several patents covering novel salivary proteins. During the past 5 years, a multidisciplinary team from the Colleges of Agriculture, Veterinary Medicine, and Science and Mathematics at Auburn has conducted research toward development of a polyvalent vaccine against horn fly feeding. In addition, this project has served to introduce at least two undergraduate students (neither of whom had previous experience with cattle) to the performance and benefits of agricultural research. In 2007, this team has performed a series of field experiments to evaluate the effect of vaccination using several of these recombinant horn fly proteins on horn fly fecundity and the immune responses of cattle to these vaccine proteins. In short, cattle were vaccinated with horn fly thrombostasin (TB8, TB3) and antithrombin (Hfx) proteins (or control protein OVA) and horn flies were allowed to feed on the cattle, after which the reproductive responses of the horn flies were measured. In addition, the cell-mediated and humoral immune responses of the cattle to the vaccine proteins were evaluated using ELISA to measure anti-vaccine antibodies and lymphocyte proliferation assays and flow cytometry to determine specific lymphocyte responses. The evaluation of the humoral immune responses is being completed and data analysis is underway. Currently, a manuscript covering work performed in 2007 is in preparation. PARTICIPANTS: PI: Dwight F. Wolfe, DVM, MS, DACVT, Professor, Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, directed the horn fly vaccine project; Co-Investigators: Dunhua Zhang, PhD, Research Scientist, Department of Entomology and Plant Pathology, College of Agriculture, Auburn University, participated in experimental design, data collection, and analysis of the molecular investigation of horn fly salivary genes; Elizabeth Whitley, DVM, PhD, Assistant Professor, Department of Pathobiology, College of Veterinary Medicine, Auburn University participated in experimental design, data collection, and analysis of the immunologic response by cattle to vaccine proteins; LaTora Todd, BS, Research Associate, Department of Entomology and Plant Pathology, College of Agriculture, Auburn University, provided laboratory support; Doug Goodwin, PhD, Associate Professor, Department of Chemistry, Auburn University; Misty Edmonson, DVM, MS, Assistant Professor, Department of Clinical Sciences, Auburn University, participated in clinical aspects of vaccination and data collection. Undergraduate education: Katherine Glynn, undergraduate student, first experience in agricultural research, assisted in the collection and analysis of data, Rory Applegate, veterinary student, assisted in the collection of data. TARGET AUDIENCES: The primary target audience includes producers of beef cattle and dairy products, and more broadly, consumers of beef and dairy products from the United States and around the world. The beef and dairy producers can be expected to have reduced costs of production with reduced numbers of horn flies which will be reflected in lower prices for these commodities for consumers. In addition, successful control of fly populations will result in improved well-being for cattle due to reduced irritation and blood-feeding caused by horn flies. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
This on-going research has resulted in incremental accumulations of knowledge, that when integrated with the results of past and future research, will allow the selection of the appropriate protein and adjuvant for vaccination against horn fly feeding. More specifically, recent work has identified differences in immune responses by cattle to two isoforms of the anti-thrombin protein, thrombostasin, from horn flies, and has identified differences in the frequency of expression of the genetic sequences encoding these isoforms by field and laboratory populations of horn flies. Increased mortality rates and delayed development cycles of fly ovarioles have been detected among flies feeding from vaccinated calves. Work performed in the most recent vaccination trial is still being analyzed. Variations in patterns expression of alleles leading to the production of thrombostasin isoforms has been determined among North and South American fly populations.
Publications
- none 2006
- Cupp MS, Cupp EW, Zhang D, Yue X, Todd L, Panangala V, Navarre C, Whitley EM. 2009 Salivary gland thrombostasin isoforms differentially regulate blood uptake of horn flies fed on New Zealand white rabbits. J. Med. Entomol, 46(2): 351-357
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