Potential effects on Rhipicephalus microplus tick larvae fed on calves immunized with a Subolesin peptide predicted by epitope analysis

Abstract

The cattle tick Rhipicephalus microplus economically impacts cattle production in tropical and subtropical regions of the world. The recombinant R. microplus Subolesin antigen has been shown to protect cattle against tick infestations. In this study, we searched in silico protective epitopes in the subolesin gene and a recombinant peptide containing the predicted epitopes was expressed, and evaluated against a tick challenge. Two different epitope types, linear B-cells and conformational discontinuous epitopes, were predicted using bioinformatics strategies, in order to synthesize the recombinant peptide. Two Eightmonth-old calves European crossbred were immunized with two subcutaneous doses of the subolesin recombinant peptide, emulsified with Montanide ISA 50 V as an adjuvant, at 30-day intervals. The tick challenge was conducted with 5 000 R. microplus larvae/animal. ELISA test was used to evaluate the IgG immune response elicited against the peptide. After tick challenge, reduction in the number of engorged females (79%), and reduction in egg hatching (30%) was observed in tick population fed on immunized calves with regards to an untreated control group. The results showed a potential higher effect on tick reproduction for the recombinant peptide compared to other studies reported with Subolesin protein, demonstrating that the use of bioinformatics strategies to predict protective epitopes may lead to improve the immune response elicited against tick recombinant peptides and therefore to prevent cattle tick infestations.