In-silico identification of potential anti-tick vaccine B-cell epitopes from rhipicephalus appendiculatus serpin proteins

Abstract

Ticks are one of the leading vectors of pathogens of both veterinary and public health importance. Currently, the mostly used tick control method is acaricides which is associated with a number of significant disadvantages including chemical contamination of food chain due to pesticide residues in meat and milk, pollution, rapid development of acaricide resistance in ticks and high costs due to the need for regular application. Anti-tick vaccine development is a promising alternative to chemical control, with benefits including environmental safety, low production costs, and relative simplicity of product registration. To contribute to research efforts to produce anti-tick vaccines, in-silico analysis of Rhipicephalus appendiculatus serpin (RAS) proteins was carried out in order to identify epitopes that can be used in a cocktail anti-tick vaccine development. Motif analysis was carried out to identify peptide motifs. Chou and Fasman-T urn, Karplus and Schulz Flexibility, BepiPred linearity, Kolaskar antigenicity and Parker-Hydrophilicity prediction models were used to predict these motifs’ potential to induce B cell mediated immune responses. A total of four motifs were identified as potential epitopes for anti-tick vaccine development one motif 181-195 was identified from RAS-1 (NCBI ID: AAK61375.1), one motif 102-130 was identified from RAS-2 (NCBI ID: AAK61376.1), motif 119-176 was identified from RAS-3 (NCBI ID: AAK61377.1) and one motif 14-63 was identified from RAS-4(NCBI ID: AAK61378.1). The motifs were mapped on the structure of their respective proteins and all the motifs were extra-cellular. The four motifs can become good starting points for development of a cocktail anti-tick vaccine. Further analyses such as molecular biology and in vivo immunization assays are required to validate these findings.