Complement evasion by the human respiratory tract pathogens Haemophilus influenzae and Moraxella catarrhalis

AbstractAll infective bacterial species need to conquer the innate immune system in order to colonize and survive in their hosts. The human respiratory pathogensHaemophilus influenzae andMoraxella catarrhalis are no exceptions, and have developed sophisticated mechanisms to evade complement ‐mediated killing. Both bacterial species carry lipooligosaccharides preventing complement attacks, and attract and utilize host complement regulators C4b binding protein and Factor H to inhibit the classical and alternative pathways of complement activation, respectively. In addition, the regulat or of the terminal pathway of complement activation, vitronectin, is hijacked by both bacteria. An array of different outer membrane proteins inH. influenzae andM. catarrhalis simultaneously binds complement regulators, but also plasminogen. Several of the bacterial complement ‐binding proteins are important adhesins and contain highly conserved regions for interactions with the host. Thus, some of the outer membrane proteins are viable targets for new therapeutics, including vaccines aimed at preventing respiratory tract diseases such as otitis media in children and ex acerbations in patients suffering from chronic obstructive pulmonary disease (COPD).
Source: FEBS Letters - Category: Biochemistry Authors: Tags: REVIEW ARTICLE Source Type: research