Analysis of gene expression in the Itu strain of Amblyomma sculptum in response to Rickettsia rickettsii infection

• Grant number: 18/07453-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2018
• End date: October 31, 2019
• Field of knowledge: Biological Sciences - Parasitology - Entomology and Malacology of Parasites and Vectors
• Principal Investigator: Andréa Cristina Fogaça
• Grantee: Thales Tadashi Kaida
• 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

Although Amblyomma sculptum (previously named Amblyomma cajennense) and Amblyomma aureolatum belong to the same genus and are important vectors of Rickettsia rickettsii, these species are distinct in relation to susceptibility to infection. A. aureolatum is more susceptible to infection than A. sculptum, providing more specimens of experimentally infected ticks. On the other hand, A. aureolatum is very sensitive to variations in environmental conditions, leading to considerable loss of specimens at each stage of the life cycle. In addition, the maintenance of the colony of A. aureolatum in the laboratory involves the experimentation with dogs in the adult phase. However, A. sculptum, despite being more resistant to infection, is resistant to environmental weather and can be fed to rabbits during all phases of its life cycle. Thus, it is fundamental to use a robust model for the experimental infection, which leads to a high number of ticks and is susceptible to infection. To date, we have used the Pedreira strain of A. sculptum to study interactions with R. rickettsii. Recently, we started the establishment of the Itu strain of A. sculptum, kindly provided by Prof. Dr. Marcelo Bahia Labruna (FMVZ-USP, collaborator of this research project), which seems to be more susceptible to infection. Thus, the main objective of this project is to evaluate the expression of genes of interest in the A. sculptum Itu strain in response to R. rickettsii infection and to evaluate the effects of the silencing of some of these genes by interfering RNA (RNAi) in the acquisition of this bacterium. The validation of A. sculptum Itu strain as a model of the interaction studies between R. rickettsii and ticks is fundamental to continue the functional studies initiated by our research group. (AU)