Thesis
Characterization of humoral immune response in horses immunized with a recombinant Bm86 protein and challenge with Rhipicephalus (Boophilus) microplus tick
Washington State University
Master of Science (MS), Washington State University
2010
Handle:
https://hdl.handle.net/2376/103745
Abstract
Babesia equi, has become a very important tick-borne parasite that is impacting the horse industry worldwide. As for both endemic and free areas, the presence of potential tick vectors capable to acquire and transmit the infection to naïve horses during mobilization, plays a very important role in Babesia equi transmission. The Rhipicephalus (Boophilus) microplus midgut protein Bm86 is a component of a partially protective anti-tick vaccine in cattle. However, whether Bm86-based vaccines also confer protection in immunized horses remained unknown. In this study we characterized the humoral immune response of horses immunized with rBm86 and challenged with Rhipicephalus (Boophilus) microplus larvae, as a preliminary step towards testing whether vaccination with rBm86 results in decreasing the fitness of Rhipicephalus (Boophilus) microplus in horses. Immunization was able to elicit a strong anti-Bm86 immune response with antibody titers between 1,000 and 10,000 at the time of tick challenge. Furthermore, characterization of the IgG sub-isotypes demonstrated a significant increase starting at week 3 after the first immunization in all IgG (T), IgGa and IgGb except for IgGc. IgG (T) was the most prevalent sub-isotype with titers greater or equal to 100,000, followed by IgGa and IgGb and not significant presence of IgGc at any of the analyzed time points. Horses from both groups, experimental and control were challenged with ≈ 2,500 R. microplus larvae per animal. Tick's feeding success, a way to assess the efficiency of the immunization, was evaluated measuring three different parameters, i.e. survival, tick weight, and eggs weight. The number of surviving ticks was significantly lower in the Bm86 group compared to the control group. No significant differences were observed either in ticks or eggs weight. All immunized animals, but one in the control group, developed a strong local skin inflammatory response in the areas where the ticks were feeding, likely interfering with the ticks feeding efficiency. Our results demonstrate that immunization with a recombinant Bm86 protein elicits a strong antibody response. However, under these experimental conditions and likely due to the strong inflammatory responses we are not able to confirm whether rBm86 immunization confers protection against tick's infestation in horses.
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Details
- Title
- Characterization of humoral immune response in horses immunized with a recombinant Bm86 protein and challenge with Rhipicephalus (Boophilus) microplus tick
- Creators
- Ma. Guadalupe Gonzalez Rodriguez
- Contributors
- Donald P. Knowles (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Veterinary Medicine, College of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525182501842
- Language
- English
- Resource Type
- Thesis