Vignette d'image

Gern, Lise

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

Résultat de la recherche

Filtres

7
7
7
Réinitialiser les filtres

Paramètres

Voici les éléments 1 - 7 sur 7
  • Publication
    Métadonnées seulement
    Isolation of Borrelia burgdorferi sensu lato from the Skin of the European Badger (Meles meles) in Switzerland
    (2009)
    Gern, Lise 
    ;
    Sell, Katy
    No data are available on the role of badgers in the ecology of Lyme borreliosis spirochetes in Europe. In a recent study describing validation of a molecular method allowing host DNA identification and Borrelia burgdorferi sensu lato detection in Ixodes ricinus, the simultaneous presence of B. afzelii DNA and of European badger (Meles meles) DNA was detected in I. ricinus ticks in Switzerland. This suggested that badgers might be reservoir hosts for B. afzelii. Here, we present results obtained in a study on badgers conducted in 1996-1997. Thirty-one tissue samples (ear biopsy: n = 25, aspiration fluid: n = 6) from 8 badgers were placed in BSK medium to isolate B. burgdorferi sensu lato and were then examined by polymerase chain reaction/ restriction fragment length polymorphism (PCR/RFLP). Globally, six Borrelia isolates (6/31, 19.4%) were obtained from 3/8 (37.5%) badgers. These isolates were identified as B. afzelii (n = 3) and B. valaisiana (n = 3).
  • Publication
    Métadonnées seulement
    Borrelia burgdorferi sensu lato, the agent of Lyme borreliosis: Life in the wilds
    (2008)
    Gern, Lise 
    In Europe, Borrelia burgdorferi sensu late (sl) the agent of Lyme borreliosis circulates in endemic areas between Ixodes ricinus ticks and a large number of vertebrate hosts upon which ticks feed. Currently, at least 12 different Borrelia species belonging to the complex B. burgdorferi sl have been identified among which seven have been defected in 1. ricinus: B. burgdorferi sensu stricto (ss), B. garinii, B. afzelii, B. valaisiana, B. spielmanii and B. bisseffii. A few dozens of vertebrate hosts have been identified as reservoirs for these Borrelia species. Specific associations were rather early observed between hosts, ticks and borrelia species, like for example between rodents and B. afzelii and B. burgdorferi ss, and between birds and B. garinii and B. valaisiana. The complement present in the blood of the hosts is the active component in the Borrelia host specificity. Recent studies confirmed trends toward specific association between Borrelia, species and particular host, but also suggested that loose associations may be more frequent in transmission cycles in nature than previously thought.
  • Publication
    Métadonnées seulement
    Ixodes ricinus density and infection prevalence of Borrelia burgdorferi sensu lato along a north-facing altitudinal gradient in the Rhône Valley (Switzerland)
    (2007)
    Burri, Caroline
    ;
    Cadenas, Francisca Moran
    ;
    Douet, Véronique 
    ;
    Moret, Jacqueline
    ;
    Gern, Lise 
    Questing Ixodes ricinus ticks were sampled monthly along a north-facing altitudinal gradient in the canton of Valais, Switzerland, from March 2004 to February 2005. Tick density and infection with Borrelia burgdorferi sensu lato were monitored. Ticks were collected by flagging vegetation at three different altitudes (750 m, 880 m, and 1020 m above sea level). Ticks were examined for Borrelia by polymerase chain reaction (PCR) followed by reverse line blot. At the three altitudes, questing tick activity was not observed under 10 degrees C and was reduced when saturation deficit was higher than 5 mm Hg, most questing tick activity was occurred between 2 mm Hg and 7 mm Hg. Tick density and peak tick density were highest at 1020 m. High saturation deficits at the lowest altitudes appear to impair the tick population. The prevalence of B. burgdorferi infection in nymphs and adults decreased with altitude. The prevalence of infection was higher in adult ticks (47%) than in nymphs (29%). Four B. burgdorferi sensu lato genospecies were detected: B. afzelii (40%), B. garinii (22%), B. valaisiana (12%) and B. burgdorferi sensu stricto (6%). Mixed infections were detected in 13% of infected ticks.
  • Publication
    Métadonnées seulement
    A comparison of two DNA extraction approaches in the detection of Borrelia burgdorferi sensu lato from live Ixodes ricinus ticks by PCR and reverse line blotting
    (2007)
    Cadenas, Francisca Moran
    ;
    Schneider, Helene
    ;
    Lommano, Elena 
    ;
    Burri, Caroline
    ;
    Moret, Jacqueline
    ;
    Gern, Lise 
    We tested two approaches to extract Borrelia DNA from live Ixodes ricinus ticks before polymerase chain reaction (PCR) and reverse line blotting (RLB): DNA extraction of one half of the tick after incubation in BSK medium and DNA extraction of the other half of the tick directly, using ammonium hydroxide. Among 2079 ticks, 31.2% (n = 649) were found to be Borrelia-infected by PCR-RLB test using at least one of the DNA extraction methods. Five hundred four ticks (24.2%) were found infected after incubation in BSK and 481 (23.1%) after direct DNA extraction from the tick. The difference was not significant. However, these prevalences were significantly lower when only one method was applied (23.1% and 24.2%) compared to the prevalence obtained by the use of both methods (31.2%). In 313 infected ticks discordant results were obtained, i.e., one half of the tick was found to be infected whereas the other half was uninfected. Among these ticks, B. garinii and B. burgdorferi sensu stricto (ss) were significantly more frequently identified in the half tick incubated in BSK. No significant differences were observed for B. burgdorferi ss, B. valaisiana, and for undetermined Borrelia species.
  • Publication
    Métadonnées seulement
    Prevalence of Borrelia burgdorferi sensu lato in ticks collected from migratory birds in Switzerland
    (2006)
    Poupon, Marie-Angèle
    ;
    Lommano, Elena 
    ;
    Humair, Pierre-François
    ;
    Douet, Véronique 
    ;
    Rais, Olivier 
    ;
    Schaad, Michael
    ;
    Jenni, Lukas
    ;
    Gern, Lise 
    The prevalence of ticks infected by Borrelia burgdorferi sensu lato on birds during their migrations was studied in Switzerland. A total of 1,270 birds captured at two sites were examined for tick infestation. Ixodes ricinus was the dominant tick species. Prevalences of tick infestation were 6% and 18.2% for birds migrating northward and southward, respectively. Borrelia valaisiana was the species detected most frequently in ticks, followed by Borrelia garinii and Borrelia lusitaniae. Among birds infested by infected ticks, 23% (6/26) were infested by B. lusitaniae-infected larvae. Migratory birds appear to be reservoir hosts for B. lusitaniae.
  • 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
    Infection of Ixodes ricinus (Acari : Ixodidae) by Borrelia burgdorferi sensu lato in North Africa
    (1999)
    Zhioua, Elyes
    ;
    Bouattour, Ali
    ;
    Hu, Chang Min
    ;
    Gharbi, Mohamed
    ;
    Aeschliman, Andre
    ;
    Ginsberg, Howard S
    ;
    Gern, Lise 
    Free-living adult Ixodes ricinus. were collected in Amdoun, situated in the Kroumiry mountains in northwestern Tunisia (North Africa). Using direct fluorescence antibody assay, the infection rate of field-collected I. ricinus bq Borrelia burgdorferi sensu late was 30.5% (n = 72). No difference in infection rate was observed between male and female ticks. Spirochetes that had been isolated from I. ricinus from Ain Drahim (Kroumiry Mountains) in 1988 were identified as Borrelia lusitaniae (formerly genospecies PotiB2). This is the first identification of a genospecies of Borrelia burgdorferi sensu lato from the continent of Africa.