Immunoprotective potential of a Rhipicephalus (Boophilus) microplus metalloprotease

- A Rhipicephalus microplus metalloprotease was expressed in Escherichia coli.
- BrRm-MP4 was used as a vaccinal antigen against R. microplus.
- Level of anti-BrRm-MP4 antibody was correlated with decrease of tick numbers.
- Immunization with tick metalloprotease provided 60% overall protection.

Ticks have serious impacts on animal and human health, causing significant economic losses in cattle breeding. Besides damage due to the hematophagous behavior, they transmit several pathogens. Low cost and environmental safety have made vaccines a promising alternative control method against tick infestation. Metalloproteases (MPs) have been shown to be essential for diverse biological functions in hematophagous organisms, inhibiting blood clotting, degrading extracellular matrix proteins, and inhibiting host tissue repair via anti-angiogenic activity. In this study, we analyzed the immunoprotective potential of a recombinant MP against Rhipicephalus (Boophilus) microplus infestation. First, a cDNA encoding R. microplus amino acids sequence with highly conserved regions of the metzincin (reprolysin) group of MP was identified (BrRm-MP4). After expression and purification, recombinant BrRm-MP4 was used as a vaccinal antigen against R. microplus infestation in cattle (Bos taurus taurus). All vaccinated bovines developed immune response to the antigen, resulting in increased antibody level throughout the immunization protocol. Immunization with rBrRm-MP4 reduced tick feeding success, decreasing the number of engorged females and their reproduction potential, representing a 60% overall protection. These results show that rBrRm-MP4 provides protection against tick infestation, placing it is a potential candidate for an anti-tick vaccine.