Optimization of Amblyomma sculptum infection by Rickettsia rickettsii

• Grant number: 17/22565-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2017
• End date: October 31, 2019
• Field of knowledge: Biological Sciences - Parasitology - Entomology and Malacology of Parasites and Vectors
• Principal Investigator: Andréa Cristina Fogaça
• Grantee: Lucas Godoi Almeida
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 13/26450-2 - Molecular characterization of the interactions among ticks, rickettsiae and vertebrate hosts, AP.TEM

Abstract

Rocky Mountain Spotted Fever (RMSF) is the most severe tick-borne ticks, presenting high lethality rates. In Brazil, the etiological agent of the disease, Rickettsia rickettsii, is transmitted to humans by the ticks Amblyomma sculptum (a species of the Amblyomma cajennense complex) and Amblyomma aureolatum. Although both species belong to the same genus and are important important vectors of R. rickettsii, they are different regarding the susceptibility to infection. While 80 to 100% of A. aureolatum ticks from a laboratory colony become infected by experimental infection, only 10 to 60% of A. sculptum ticks become infected. Our research group has previously analyzed the effects of R. rickettsii infection on the gene expression profile of the intestine and the salivary glands of A. aureolatum and A. sculptum ticks. The role played by some proteins were determined in both models by interference RNA. Although A. aureolatum is more susceptible to infection, it is quite sensitive to variations in environmental conditions, leading to considerable losses of specimens at each stage of the life cycle. In addition, colony maintenance in the laboratory involves the feeding of adults on dogs. On the other hand, A. sculptum, although refractory to infection, is resistant and can be feed on rabbits during all phases of its life cycle. The main objective of this project is to establish, in the laboratory, a colony of A. sculptum more susceptible to infection, providing a high number of ticks for functional studies. (AU)