Outer membrane protein OlpA contributes to Moraxella catarrhalis serum resistance via interaction with factor H and the alternative pathway.

Sara Bernhard, Christophe Fleury, Yu-Ching Su, Peter F Zipfel, Iris Koske, Therése Nordström, Kristian Riesbeck

Index: J. Infect. Dis. 210(8) , 1306-10, (2014)

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Abstract

Factor H is an important complement regulator of the alternative pathway commonly recruited by pathogens to achieve increased rates of survival in the human host. The respiratory pathogen Moraxella catarrhalis, which resides in the mucosa, is highly resistant to the bactericidal activity of serum and causes otitis media in children and respiratory tract infections in individuals with underlying diseases. In this study, we show that M. catarrhalis binds factor H via the outer membrane protein OlpA. M. catarrhalis serum resistance was dramatically decreased in the absence of either OlpA or factor H, demonstrating that this inhibition of the alternative pathway significantly contributes to the virulence of M. catarrhalis. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.