Interaction of Complement System Components with Bacterial Outer Membrane Proteins and Presentation of Techniques Useful in Studying these Interactions

Abstract

The complement (C) system participates in the immune response against pathogenic microorganisms. C3 protein plays a crucial role because its activation supports the course of the three pathways of the C cascade: the alternative pathway (AP), the classical pathway (CP), and the lectin pathway (LP) leading to the destruction of microorganisms and limitation of the infection. This paper attempts to highlight the role of outer membrane proteins (OMPs) in C components binding, as there are porins able to alter the course of C activation. Additionally, we present molecular methods adapted to C3 activation in human serum upon a contact with Salmonella cells and their OMPs. We demonstrate our achievements by using Salmonella strains as an exemplary microorganism of the public importance. The most severe outcomes of the presence of vital Salmonella rods in human body is sepsis. Therefore, it is desirable to do research on the C evasion mechanisms developed by pathogens, to understand the principles of bacteremia caused by other pathogens. We propose four techniques that may be useful in studying interactions between bacterial surfaces and C components: electrophoretic resolution of OMPs under denaturing and non-denaturing conditions, western blotting, and sandwich ELISA. Keywords: BN-PAGE, C3, outer membrane protein, Salmonella, sandwich ELISA, SDS-PAGE.