Comparison of Protein Gut Samples from Rhipicephalus spp. Using a Crude and an Innovative Preparation Method for Proteome Analysis

Report from the 'One Health' 9th Tick and Tick-Borne Pathogen Conference and the 1st Asia-Pacific Rickettsia Conference, Cairns, Australia, 27th August-1st September 2017

The 9th Tick and Tick-borne Pathogen (TTP9) Conference was held in conjunction with the first Asia Pacific Rickettsia Conference (APRC1) in Cairns, Australia from 27 August until 1 September in 2017. This MDPI Veterinary Sciences Special Issue has been dedicated to selected veterinary science articles from the conference associated with the control of animal diseases in the context of ticks and tick-borne pathogens, including Rickettsia species. The articles presented in this Special Issue include novel developments for the future control of ticks and tick-borne diseases. This editorial describes the meeting content, the plenaries, the TTP awards, the MDPI Veterinary Science Special Issue articles, and serves as a legacy report for TTP9APRC1.

Novel and Selective Rhipicephalus microplus Triosephosphate Isomerase Inhibitors with Acaricidal Activity

The cattle tick Rhipicephalus microplus is one of the most important ectoparasites causing significant economic losses for the cattle industry. The major tool of control is reducing the number of ticks, applying acaricides in cattle. However, overuse has led to selection of resistant populations of R. microplus to most of these products, some even to more than one active principle. Thus, exploration for new molecules with acaricidal activity in R. microplus has become necessary. Triosephosphate isomerase (TIM) is an essential enzyme in R. microplus metabolism and could be an interesting target for the development of new methods for tick control. In this work, we screened 227 compounds, from our in-house chemo-library, against TIM from R. microplus. Four compounds (50, 98, 14, and 161) selectively inhibited this enzyme with IC₅₀ values between 25 and 50 μM. They were also able to diminish cellular viability of BME26 embryonic cells by more than 50% at 50 μM. A molecular docking study showed that the compounds bind in different regions of the protein; compound 14 interacts with the dimer interface. Furthermore, compound 14 affected the survival of partially engorged females, fed artificially, using the capillary technique. This molecule is simple, easy to produce, and important biological data—including toxicological information—are available for it. Our results imply a promising role for compound 14 as a prototype for development of a new acaricidal involving selective TIM inhibition.