The paralogous salivary anti-complement proteins IRAC I and IRAC II encoded by Ixodes ricinus ticks have broad and complementary inhibitory activities against the complement of different host species.
Animals; Birds; Complement Inactivator Proteins/metabolism; Complement Pathway, Alternative; Complement System Proteins/immunology; Humans; Ixodes/metabolism/pathogenicity; Mammals; Species Specificity
Abstract :
[en] Several observations suggest that inhibition of the host complement alternative pathway by Ixodes tick saliva is crucial to achieve blood feeding. We recently described two paralogous anti-complement proteins called Ixodes ricinus anti-complement (IRAC) proteins I and II co-expressed in I. ricinus salivary glands. Phylogenetic analyses suggested that these sequences were diversifying by a process of positive Darwinian selection, possibly leading to molecules with different biological properties. In the present study, we tested the hypothesis that each paralogue may have different inhibitory activities against the complement of different natural host species, thereby contributing to broaden the host range of I. ricinus ticks. IRAC I and IRAC II were tested against the complement of eight I. ricinus natural host species (six mammals and two birds). The results demonstrate that IRAC I and IRAC II have broad and complementary inhibition activities against the complement of different host species. This report is the first description of paralogous anti-complement molecules encoded by a pathogen with broad and complementary inhibitory activities against the complement of different host species.
Disciplines :
Veterinary medicine & animal health Immunology & infectious disease
Author, co-author :
Schroeder, Hélène ; Université de Liège - ULiège > Immunologie et vaccinologie
The paralogous salivary anti-complement proteins IRAC I and IRAC II encoded by Ixodes ricinus ticks have broad and complementary inhibitory activities against the complement of different host species.
Lawrie C.H., Randolph S.E., and Nuttall P.A. Ixodes ticks: serum species sensitivity of anticomplement activity. Exp. Parasitol. 93 (1999) 207-214
Valenzuela J.G., Charlab R., Mather T.N., and Ribeiro J.M. Purification, cloning, and expression of a novel salivary anticomplement protein from the tick, Ixodes scapularis. J. Biol. Chem. 275 (2000) 18717-18723
Ribeiro J.M., Alarcon-Chaidez F., Francischetti I.M., Mans B.J., Mather T.N., Valenzuela J.G., and Wikel S.K. An annotated catalog of salivary gland transcripts from Ixodes scapularis ticks. Insect Biochem. Mol. Biol. 36 (2006) 111-129
V. Daix, H. Schroeder, N. Praet, J.-P. Georgin, I. Chiappino, L. Gillet, K. de Fays, Y. Decrem, G. Leboulle, E. Godfroid, A. Bollen, P.-P. Pastoret, L. Gern, P.M. Sharp, A. Vanderplasschen, Ixodes ticks belonging to the Ixodes ricinus complex encode a family of anti-complement proteins, Insect Mol. Biol., in press.
Gillet L., Daix V., Donofrio G., Wagner M., Koszinowski U.H., China B., Ackermann M., Markine-Goriaynoff N., and Vanderplasschen A. Development of bovine herpesvirus 4 as an expression vector using bacterial artificial chromosome cloning. J. Gen. Virol. 86 (2005) 907-917