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  • Publication
    Métadonnées seulement
    Ixodes ticks belonging to the Ixodes ricinus complex encode a family of anticomplement proteins
    (2007)
    Daix, Virginie
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    Schroeder, Hélène
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    Praet, N
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    Georgin, Jean-Pierre
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    Chiappino, I
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    Gillet, Laurent
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    de Fays, Katalin
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    Decrem, Yves
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    Leboulle, Gérard
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    Godfroid, Edmond
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    Bollen, Alex
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    Pastoret, Paul-Pierre
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    Sharp, Paul
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    Vanderplasschen, Alain
    The alternative pathway of complement is an important innate defence against pathogens including ticks. This component of the immune system has selected for pathogens that have evolved countermeasures. Recently, a salivary protein able to inhibit the alternative pathway was cloned from the American tick Ixodes scapularis (Valenzuela et al., 2000; J. Biol. Chem. 275, 18717-18723). Here, we isolated two different sequences, similar to Isac, from the transcriptome of I. ricinus salivary glands. Expression of these sequences revealed that they both encode secreted proteins able to inhibit the complement alternative pathway. These proteins, called I. ricinus anticomplement (IRAC) protein I and II, are coexpressed constitutively in I. ricinus salivary glands and are upregulated during blood feeding. Also, we demonstrated that they are the products of different genes and not of alleles of the same locus. Finally, phylogenetic analyses demonstrate that ticks belonging to the Ixodes ricinus complex encode a family of relatively small anticomplement molecules undergoing diversification by positive Darwinian selection.
  • Publication
    Métadonnées seulement
    PCR-reverse line blot typing method underscores the genomic heterogeneity of Borrelia valaisiana species and suggests its potential involvement in Lyme disease
    (2003)
    Godfroid, Edmond
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    Hu, Chang Min
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    Humair, Pierre-François
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    Bollen, Alex
    ;
    Detection of the Borrelia burgdorferi sensu lato complex in biological samples is currently done by conventional immunological and molecular biological methods. To improve on the accuracy of these methods and to simplify the procedure for testing large numbers of samples, a solid-phase sandwich hybridization system readily applicable to the detection of PCR products has been designed. This colorimetric detection system relies on the use of polybiotinylated detection probes and of specific capture oligonucleotides covalently linked at allocated positions on nylon membrane strips. From a phylogenetic analysis on a great number of ospA gene sequences, we have designed and synthesized a set of PCR primers specific to the five Borrelia burgdorferi sensu lato genospecies present in Europe and a subset of probes (capture and detection probes) specific to these five genospecies (B. burgdorferi sensu stricto, B. garinii, B. afzelii, B. valaisiana, and B. lusitaniae). This combined PCR hybridization system was evaluated with a large number of various B. burgdorferi isolates and clinical specimens. These analyses clearly showed that the system could be used as a typing method to distinguish five genospecies belonging to the B. burgdorferi sensu lato complex. In addition, the study showed that B. valaisiana strains might be more heterologous than suspected up to now and clustered into three genomic groups.