Immunization of cattle with a Rhipicephalus microplus chitinase peptide containing predicted B-cell epitopes reduces tick biological fitness

Authors: PEREZ-SORIA, MARIA - Autonomous University Of Queretaro; LOPEZ-DIAZ, DANIEL - Autonomous University Of Queretaro; JIMÉNEZ-OCAMPO, RAFAEL - National Institute Of Forestry, Agricultural And Livestock Research; AGUILAR-TIPACAMU, GABRIELA - Autonomous University Of Queretaro; Ueti, Massaro; MOSQUEDA, JUAN - Autonomous University Of Queretaro

Submitted to: Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2024
Publication Date: 2/5/2024
Citation: Perez-Soria, M.M., Lopez-Diaz, D.G., Jiménez-Ocampo, R., Aguilar-Tipacamu, G., Ueti, M.W., Mosqueda, J. 2024. Immunization of cattle with a Rhipicephalus microplus chitinase peptide containing predicted B-cell epitopes reduces tick biological fitness. Parasitology. https://doi.org/10.1017/S0031182024000143.
DOI: https://doi.org/10.1017/S0031182024000143

Interpretive Summary: Rhipicephalus microplus, an ectoparasite, has a significant economic impact on the livestock industry worldwide. The continuous use of chemical treatments led to the emergence of acaricide-resistant tick populations. An immunological strategy based on vaccines offers an alternative approach to tick control infestation. In this study, R. microplus chitinase was identified and evaluated as a vaccine candidate. Four peptides containing predicted B-cell epitopes were designed. The immunogenicity of each peptide was assessed by immunizing cattle. The result showed that chitinase peptide-3 significantly reduced the weight and oviposition of engorged ticks, as well as larvae viability. Chitinase 3 appears as a viable vaccine candidate for tick control.

Technical Abstract: Rhipicephalus microplus, the cattle fever tick, is the most important ectoparasite impacting the livestock industry worldwide. Overreliance on chemical treatments for tick control has led to the emergence of acaricide-resistant ticks and environmental contamination. An immunological strategy based on vaccines offers an alternative approach to tick control. To develop novel tick vaccines, it is crucial to identify and evaluate antigens capable of generating protection in cattle. Chitinases are enzymes that degrade older chitin at the time of molting, therefore allowing interstadial metamorphosis. In this study, one R. microplus chitinase was identified and evaluated as vaccine candidate. First, the predicted amino acid sequence was determined in four isolates and their similarity were analysed by bioinformatics. Four peptides containing predicted B-cell epitopes were designed. The immunogenicity of each peptide was assessed by inoculating two cattle, four times at 21-days intervals, and the antibody response was verified by indirect ELISA. A vaccine efficacy experiment was conducted on those that were immunogenic. The chitinase gene was successfully amplified and sequenced, enabling comparison with reference strains. Notably, more than 99 % conservation was ascertained among the sequences. Furthermore, native protein recognition was demonstrated through western blot assays. Chitinase peptide 3 significantly reduced the weight and oviposition of engorged ticks, as well as larvae viability, exhibiting a 71 % efficacy. Therefore, chitinase 3 emerges as a viable vaccine candidate, holding promise for its integration into a multiantigenic vaccine against R. microplus