Identification and functional characterization of hemolymph proteins from Amblyomma aureolatum ticks differentially expressed in response to Rickettsia rickettsii infection

• Grant number: 17/13776-8
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: August 01, 2017
• End date: April 30, 2019
• Field of knowledge: Biological Sciences - Parasitology - Entomology and Malacology of Parasites and Vectors
• Principal Investigator: Andréa Cristina Fogaça
• Grantee: Leticia Monica Coimbra Gaziola
• 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 is caused by the bacterium Rickettsia rickettsii, which is transmitted to humans by tick bites. In Brazil, the tick Amblyomma aureolatum is an important vector of R. rickettsii. The interactions between pathogens and their vectors are closely related to the physiological aspects of blood feeding. After the acquisition of the blood meal, host blood is processed in the midgut of the hematophagous arthropod to acquire nutrients and energy. If the ingested blood contains microorganisms, they must be able to resist to the effects of both hemolytic and antimicrobial factors that are produced by the intestinal epithelium. In addition, the pathogen must colonize and/or cross the midgut epithelium, getting to the hemocoel of the arthropod vector, filled with hemolymph, where it suffers the attack of both cellular and humoral immune reactions. If the microorganism succeeds in evading the immune reactions of the hemolymph, it still needs to be able to invade the salivary glands and reach to the saliva, through which it will be transmitted to the vertebrate host during a subsequent blood meal. Thus, the identification of the molecules that participate in each of these steps becomes fundamental, and may provide information for the development of new biotechnological tools to block the transmission of these pathogens. The main objective of the current study is to identify, by a proteomic approach, the proteins of the hemolymph of A. aureolatum that are differentially expressed in response to R. rickettsii infection. Some of these proteins will be selected for functional characterization using RNA interference (RNAi)-mediated gene silencing. The proteins identified and characterized by the present study might be used as targets for the development of vaccines for the control of both tick and rickettsia in the future. (AU)