Mechanisms of Activation and Evasion of The Complement System by Pathogens

The complement system plays crucial biological roles in both innate and adaptive immune responses. This important humoral arm of innate immunity provides initial defence against invading pathogens. Even so, a number of microorganisms may cause harmful infections because they have evolved sophisticated strategies to circumvent the immune defence systems of a variety of hosts, notably mechanisms to escape complement activation and ⁄ or lytic complement attack. Among these mechanisms are the recruitment or mimicking of complement regulators, the secretion of endogenous proteases or the acquisition of host´s proteases that inactivate key complement components, and the inhibition of complement proteins by direct interactions. Passive features such as the cell wall of Gram-positive bacteria prevent terminal complement complex deposition also contributing to complement evasion.
A better knowledge of how pathogens escape human immune responses not only contributes to understanding disease mechanisms but also paves the way towards novel therapeutic approaches.

In this Research Topic “Mechanisms of activation and evasion of the complement system by pathogens” we welcome the submission of original articles, reviews and mini-reviews, as well as opinion pieces related to the field. Updates and exciting recent findings on how Gram-positive and Gram-negative bacteria, protozoa, mycobacteria, viruses, fungi, and parasites circumvent the host´s innate immune responses will potentially impact the development of specific therapeutics to combat important human infections.