Protein deposition of human complement system in pathogenic and non pathogenic leptospira species

• Grant number: 16/05675-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2016
• End date: May 31, 2017
• Field of knowledge: Biological Sciences - Immunology - Immunochemistry
• Principal Investigator: Lourdes Isaac
• Grantee: Leonardo Moura Midon
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The leptospira bacteria is a spirochete that causes leptospirosis, one of the most important zoonoses ocurring in developing countries with tropical and mild climate, affecting approximately one million individuals every year. The occurrence of floods and lack of adequate sanitation allow the contact of the urine of infected animals (especially rodents) with water and soil, contaminating them. These micro-organisms have extracellular lifes and can activate innate and adaptive immune response, such as: phagocytosis; the generation of specific antibodies and activation of the complement system. The complement system is composed of several soluble proteins that can be found on the surface of various cell types. Once activated, they can contribute to the elimination of micro-organisms, generating opsonins that are deposited in the pathogen (facilitating phagocytosis); forming the Membrane Attack Complex (MAC), responsible for cell lysis; recruiting immune system cells by chemotaxis; among many other functions. Non-pathogenic Leptospira are quickly eliminated by the alternative pathway of the complement system, whereas pathogenic Leptospira are sturdy and can escape this activation. In this project we'll analyze the deposition of proteins C3, C5, C6, C7, C8 and C9 of the human complement system on the surface of these bacteria, as a result of the Complement System activation. We'll compare the deposition of these proteins between two kinds of non-pathogenic Leptospira and seven species of pathogenic Leptospira.