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Gern, Lise

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Gern, Lise
Affiliation principale
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Ancien.ne collaborateur.trice
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https://libra.unine.ch/handle/123456789/303

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  • Publication
    Accès libre
    Complementation of a Borrelia afzelii OspC mutant highlights the crucial role of OspC for dissemination of Borrelia afzelii in Ixodes ricinus
    (2007)
    Fingerle, Volker
    ;
    Goettner, Gereon
    ;
    Gern, Lise 
    ;
    Wilske, Bettina
    ;
    Schulte-Spechtel, Ulrike
    Alteration of the outer surface protein (Osp) composition – especially that of OspA and OspC – seems to be important for the adaptation of Borrelia burgdorferi sensu lato to its endothermic hosts (mammals) and poikilothermic vectors (ticks). OspA possibly mediates adherence to tick midgut cells thus enabling the borreliae to survive in the vector, while OspC is associated with borrelial invasion of the tick salivary glands and infection of the mammalian hosts. Here we describe the first successful transformation and complementation of a Borrelia afzelii ospC mutant with the wild-type ospC in trans. To test the influence of OspC on the dissemination behavior in ticks, unfed Ixodes ricinus nymphs were artificially infected by capillary feeding either with B. afzelii wild type, the B. afzelii ospC mutant or the ospC-complemented clone. Tick midguts and salivary glands were investigated after different time intervals for the presence of borreliae and for OspA and OspC by immunfluorescence staining with monoclonal antibodies. While the B. afzelii wild-type strain exhibiting abundant OspC on its surface disseminated to the salivary glands, the OspC-negative mutant was only present in the tick midguts. The ospC-complemented clone which constitutively expresses the wild-type ospC was again able to colonize the salivary glands. This finding demonstrates that OspC is crucial for dissemination of B. afzelii from the tick midgut to the salivary glands, a prerequisite for infection of the warm-blooded host. A summary of the detailed data presented here has already been given in Goettner et al. [2006. OspC of B. afzelii is crucial for dissemination in the vector as shown by transformation and complementation of a European OspC-deficient B. afzelii strain. Int. J. Med. Microbiol. 296S1(Suppl. 40), 122–124].
  • Publication
    Métadonnées seulement
    OspC of Borrelia afzelii is crucial for dissemination in the vector as shown by transformation and complementation of a European OspC-deficient B. afzelii strain
    (: Elsevier Gmbh, Urban & Fischer Verlag, 2005)
    Goettner, Gereon
    ;
    Gern, Lise 
    ;
    Schulte-Spechtel, Ulrike
    ;
    Wilske, Bettina
    ;
    Fingerle, Volker
  • Publication
    Métadonnées seulement
    Dynamics of dissemination and outer surface protein expression of different European Borrelia burgdorferi sensu lato strains in artificially infected Ixodes ricinus nymphs
    (2002)
    Fingerle, Volker
    ;
    Rauser, Sandra
    ;
    Hammer, Bettina
    ;
    Kahl, Olaf
    ;
    Heimerl, Christiane
    ;
    Schulte-Spechtel, Ulrike
    ;
    Gern, Lise 
    ;
    Wilske, Bettina
    Unfed Ixodes ricinus nymphs were infected with eight different strains and clones of Borrelia afzelii and B. garinii by capillary feeding. Except one B. afzelii clone, all expressed OspC in culture. Tick midguts and salivary glands were investigated at different time intervals for the presence of borreliae and for OspA and OspC phenotypes by immunofluorescence with simultaneous staining of OspA and OspC with monoclonal antibodies. Both species were transmittable to L ricinus. All OspC-expressing strains and clones were able to disseminate into the salivary glands. In contrast, the OspC-negative B. afzelii clone was not detectable in the salivary glands, an indication that OspC plays an important role in dissemination. OspA-positive borreliae prevailed in the midgut. OspC positives were more frequent in the salivary glands than in the midgut. Notably, simultaneously OspA- and OspC-negative borreliae were detected in both organs. Kinetics of dissemination varied with the strains. The OspC-positive B. afzelii clone and all B. garinii OspA type 4 strains were detectable in the salivary glands right after feeding, while one B. garinii OspA type 6 strain invaded the salivary glands with a delay of 24 h. These findings support the hypothesis that OspA is abundantly expressed in unfed ticks while upregulation of OspC is also a prerequisite for dissemination in the vector for the Eurasian species B. afzelii and B. garinii. However, we found strain-specific dynamics of Osp expression and strain-specific kinetics of systemic infection in the vector tick and it appears that additional factors are involved in the initiation and regulation of the dissemination process.