Binding of properdin to patogenic and apatogenic Leptospira serovares. Contribuition to the efector mechanisms of complement system in the innate immunity

• Grant number: 09/11456-0
• Support Opportunities: Scholarships in Brazil - Master
• Start date: March 01, 2010
• End date: April 30, 2012
• Field of knowledge: Biological Sciences - Immunology - Immunochemistry
• Principal Investigator: Lourdes Isaac
• Grantee: Adriana Patricia Granados Martínez
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Leptospirosis is one of the most important zoonoses, mainly in developing countries. This disease is caused by Leptospira. Once infected the host, this bacteria spreads through the blood and lymphatic circulations, to most of tissues, multiplying in the liver and spleen. Leptospiras are extracellular bacteria inducing the activation of several immune effector mechanisms such as antibody production, activation of the complement system and phagocytosis. However, there are several Leptospira serovares capable to incorporate complement regulatory proteins such as Factor H and C4BP on the external membrane. The activation of alternative pathway of the complement system is important for leptospira killing. Properdin is a positive regulatory protein which stabilizes de C3- and C5- convertases of the alternative pathway.We would like to investigate if pathogenic an apathogenic serovares of Leptospira bind equally to properdin. We also would like to study if this binding occurs directly to the bacteria membrane or if depends on the C3b deposition on their surface.Finally we will investigate if properdin acts as an opsonin, enhancing the bacteria phagocytosis.