Prova de conceito e aprimoramento biotecnológico de alvos antigênicos para compor a primeira vacina contra o carrapato de cães Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae)

Abstract

Ticks are one of the most important groups among the vectors of Phylum Arthropoda, compared only to mosquitoes. These arthropods can affect the host through blood spoliation or transmission of various pathogens, including viruses, bacteria, helminths and protozoa. In veterinary medicine the Rhipicephalus sanguineus, highly specific dog, is of great relevance given the diversity of transmitted pathogens, especially Babesia vogeli, Ehrlichia canis, Hepatozoon canis and Anaplasma platys. In addition, this tick has a wide geographic distribution, with cases reported in the South, Central and North America, Asia, Africa, Oceania and Europe. Traditionally, the methods used to control ticks consist of the application of chemicals, but with reduced effectiveness in controlling the population. Increasing resistance to these compounds is a major problem for the veterinary industry as the cost of developing new formulations is very high, making the continued development of new chemical compounds complex. This demonstrates the need for the development of new strategies for sustainable control of tick populations. In this sense, the present study was designed to identify and evaluate specific R. sanguineus antigenic targets with potential to interfere with their biological cycle, so that they can be used as an alternative tick control strategy. Initially (Chapter I) the proof-of-concept study employing immunization with R. sanguineus antigens (RsSap) in BALB/c mice and mongrel dogs. At this stage it was observed that the formulation was considered safe and reduced survival in all evolutionary stages of the tick (larva, nymph and adult), besides reducing the amount of eggs generated by the teleogins, indicating the potential of the evaluated antigens. In the next step of this study (Chapter II), antiRsSap antibodies were used to identify new phage display vaccine targets. Thus, six different antigenic sequences (S1-6) were identified. In the final step of this study (Chapter III), these sequences separately composed different vaccine formulations that were evaluated in a new preclinical trial. The results showed that all vaccine formulations were considered safe and harmless. In addition, it was found that the formulations evaluated presented high antigenicity and high potential for interference in the R. sanguineus biological cycle, reaching 99.57% efficacy. This study demonstrated for the first time that it is possible to have a tick vaccine against R. sanguineus, with biotechnological characteristics that favor its large-scale production.