Genetic profile and susceptibility of different populations of the tick Amblyomma sculptum to the infection by the pathogen Rickettsia rickettsii

• Grant number: 13/14222-5
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: September 01, 2013
• End date: July 31, 2016
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Preventive Veterinary Medicine
• Principal Investigator: Marcelo Bahia Labruna
• Grantee: Monize Gerardi
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Brazilian spotted fever (BSF), caused by the bacterium Rickettsia rickettsii, is the tick-borne disease of greatest medical importance in Latin America, where the disease is transmitted mainly by the Cayenne tick, Amblyomma cajennense. The present proposal aims: (i) to evaluate, under laboratory conditions, the susceptibility of five geographically distinct populations of A. cajennense to the infection by R. rickettsii, in order to correlate the different susceptibilities to the genetic profiles of the tick populations; and (ii) to perform a comparative analysis of the dynamics of the R. rickettsii infection in five geographically distinct populations of A. cajennense, through the quantification of the transestadial perpetuation and transovarial transmission of the bacterium in ticks. For these purposes, five different populations of A. cajennense will be evaluated, being two from BSF-endemic areas in the state of São Paulo, and three from non-endemic areas in the states of São Paulo, Mato Grosso and Minas Gerais. The five populations were exposed to the infection by R. rickettsii strain ITU, which was originally isolated from A. cajennense in São Paulo. The results of the experimental infections will allow to verify if there are differences on the susceptibilities of different A. cajennense populations to a R. rickettsii strain that was originally isolated from one of the tested tick populations. The results will be compared with the genetic profiles of the tick populations, through the DNA sequences that will be generated in this study for the 16S mitochondrial and nuclear ITS2 markers. The results will also allow a more robust evaluation of the dynamics of the R. rickettsii infection in A. cajennense, through the quantification of the transestadial perpetuation and transovarial transmission of the bacterium in the five tick populations.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

GERARDI, MONIZE; RAMIREZ-HERNANDEZ, ALEJANDRO; BINDER, LINA C.; KRAWCZAK, FELIPE S.; GREGORI, FABIO; LABRUNA, MARCELO B.. Comparative Susceptibility of Different Populations of Amblyomma sculptum to Rickettsia rickettsii. FRONTIERS IN PHYSIOLOGY, v. 10, MAY 28 2019. (13/14222-5, 13/18046-7)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

GERARDI, Monize. Genetic profile and susceptibility of different Amblyomma sculptum tick populations to infection by Rickettsia rickettsia pathogen. 2016. Doctoral Thesis - Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD) São Paulo.