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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
    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
    ;
    Hu, Chang Min
    ;
    Humair, Pierre-François
    ;
    Bollen, Alex
    ;
    Gern, Lise 
    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.
  • Publication
    Métadonnées seulement
    Resolution of experimental and tick-borne Borrelia burgdorferi infection in mice by passive, but not active immunization using recombinant OspC
    (1999)
    Zhong, Weimin
    ;
    Gern, Lise 
    ;
    Stehle, Thomas
    ;
    Museteanu, Crisan
    ;
    Kramer, Michael
    ;
    Wallich, Reinhard
    ;
    Simon, Markus M
    Vaccination with outer surface protein A (OspA) of Borrelia burgdorferi prevents subsequent infection and disease in both laboratory animals and humans with high efficacy. OspA-based immunity, however, does not affect established infection due to the loss of OspA expression in the vertebrate host. We show here that repeated passive transfer of mouse and/or rabbit immune sera to recombinant GST-OspC fusion protein resulted in a dose-dependent resolution (1) of fully established arthritis and carditis as well as infection in needle-challenged C.B-17 SCID and (2) of infection in both experimentally and tick-infected BALB/c mice. Unexpectedly, active immunization of disease-susceptible AKR/N mice with GST-OspC only led to prevention but not resolution of disease and infection, in spite of high serum titers of OspC-specific Ab and the expression of ospC in tissue-derived spirochetes. The data suggest that the efficacy of OspC antibody-mediated immunity depends on the immunological history of the recipient and/or environment-dependent regulation of OspC surface expression by spirochetes in vivo. The results encourage further attempts to develop therapeutic vaccination protocols against Lyme disease.
  • Publication
    Métadonnées seulement
    Expression of outer surface proteins A and C of Borrelia afzelii in Ixodes ricinus ticks and in the skin of mice
    (1998)
    Leuba-Garcia, S
    ;
    Martinez, R
    ;
    Gern, Lise 
    Several studies have described changes in the expression of proteins, especially of OspA and OspC, of B. burgdorferi sensu stricto during tick feeding. In this study, the expression of OspA and OspC of B. afzelii in unfed and feeding I. ricinus nymphs and in the subsequent adults was followed by means of the immunofluorescence test. Spirochaetes expressing OspA and OspC were observed in 70% and 80%, respectively of the unfed nymphs. In feeding and in fully engorged ticks, spirochaetes expressed OspC, while OspA disappeared 24 hours after the beginning of the blood meal. Spirochaetes expressing OspC in salivary glands were observed in one engorged tick. After molting, in unfed adults spirochaetes again expressed OspA and OspC but did so less frequently (6% and 13%, respectively). The mouse strain (AKR/N or BALB/C) on which ticks had their infectious blood meal influenced OspC expression in the following tick stage. In the skin of AKR/N mice, at the tick feeding site, B. afzelii expressed OspC only, as was shown by immunostaining.
  • Publication
    Métadonnées seulement
    Therapeutic passive vaccination against chronic Lyme disease in mice
    (1997)
    Zhong, Weimin
    ;
    Stehle, Thomas
    ;
    Museteanu, Crisan
    ;
    Siebers, Annette
    ;
    Gern, Lise 
    ;
    Kramer, Michael
    ;
    Wallich, Reinhard
    ;
    Simon, Markus M
    Passive and active immunization against outer surface protein A (OspA) has been successful in protecting laboratory animals against subsequent infection with Borrelia burgdorferi. Antibodies (Abs) to OspA convey full protection, but only when they are present at the time of infection, Abs inactivate spirochetes within the tick and block their transmission to mammals, but do not affect established infection because of the loss of OspA in the vertebrate host. Our initial finding that the presence of high serum titers of anti-OspC Abs (5 to 10 mu g/ml) correlates with spontaneous resolution of disease and infection in experimentally challenged immunocompetent mice suggested that therapeutic vaccination with OspC may be feasible. We now show that polyclonal and monospecific mouse immune sera to recombinant OspC, but not to OspA, of B. burgdorferi resolve chronic arthritis and carditis and clear disseminated spirochetes in experimentally infected C.B.-17 severe combined immunodeficient mice in a dose-dependent manner. This was verified by macroscopical and microscopical examination of affected tissues and recultivation of spirochetes from ear biopsies. Complete resolution of disease and infection was achieved, independent of whether OspC-specific immune sera (10 mu g OspC-specific Abs) were repeatedly given (4 x in 3- to 4-day intervals) before the onset (day 10 postinfection) or at the time of fully established arthritis and carditis (days 19 or 60 postinfection). The results indicate that in mice spirochetes constitutively express OspC and are readily susceptible to protective OspC-specific Abs throughout the infection. Thus, an OspC-based vaccine appears to be a candidate for therapy of Lyme disease.