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Variability and Action Mechanism of a Family of Anticomplement Proteins in <i>Ixodes ricinus</i>
Auteur(s)
Couvreur, Bernard
Beaufays, Jérôme
Charon, Cédric
Lahaye, Kathia
Gensale, François
Denis, Valérie
Charloteaux, Benoît
Decrem, Yves
Prévôt, Pierre-Paul
Vanhamme, Luc
Godfroid, Edmond
Date de parution
2008
In
PLoS One, Public Library of Science (PloS), 2008/3/1/e1400 1-24
Résumé
<b><i>Background</i></b> : Ticks are blood feeding arachnids that characteristically take a long blood meal. They must therefore counteract host defence mechanisms such as hemostasis, inflammation and the immune response. This is achieved by expressing batteries of salivary proteins coded by multigene families. <br> <b><i>Methodology/Principal Findings</i></b> : We report the in-depth analysis of a tick multigene family and describe five new anticomplement proteins in <i>Ixodes ricinus</i>. Compared to previously described <i>Ixodes</i> anticomplement proteins, these segregated into a new phylogenetic group or subfamily. These proteins have a novel action mechanism as they specifically bind to properdin, leading to the inhibition of C3 convertase and the alternative complement pathway. An excess of non-synonymous over synonymous changes indicated that coding sequences had undergone diversifying selection. Diversification was not associated with structural, biochemical or functional diversity, adaptation to host species or stage specificity but rather to differences in antigenicity. <br> <b><i>Conclusions/Significance</i></b> : Anticomplement proteins from <i>I. ricinus</i> are the first inhibitors that specifically target a positive regulator of complement, properdin. They may provide new tools for the investigation of role of properdin in physiological and pathophysiological mechanisms. They may also be useful in disorders affecting the alternative complement pathway. Looking for and detecting the different selection pressures involved will help in understanding the evolution of multigene families and hematophagy in arthropods.
Identifiants
Type de publication
journal article
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