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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
    Molecular identification of bloodmeal source in Ixodes ricinus ticks using 12S rDNA as a genetic marker
    (2007)
    Humair, Pierre-François
    ;
    Douet, Véronique 
    ;
    Cadenas, Francisca Moran
    ;
    Schouls, Leo M
    ;
    Van de Pol, Ingrid
    ;
    Gern, Lise 
    We developed an efficient molecular method for the identification of the bloodmeal sources in the tick Ixodes ricinus (L.), the European vector of the agents of Lyme borreliosis and tick-borne encephalitis. A approximate to 145-bp orthologous fragment of the vertebrate mitochondrial 12S rDNA was used as a molecular marker to discriminate host vertebrate species. The method consists of a single run polymerase chain reaction amplification of the 12S rDNA molecular marker by using nondegenerate primers followed by a reverse line blot hybridization assay by using specific oligonucleotide probes. The palette of probes allowed us to distinguish major groups of host vertebrates (e.g., mammals, small rodents, artiodactyls, birds, lizards) and to identify the bloodmeal sources at the genus or species level. External primers were designed and used to sequence the 12S rDNA molecular marker of a broad range of known or potential host vertebrate species (n = 60), including mammal (n = 28), bird (n = 31), and reptile (n = 1) species. The use of this technique coupled with known methods for identification of tick-borne pathogens (e.g., Borrelia burgdorferi sensu lato) allowed us to determine the source of infective bloodmeal and to identify reservoir species. The present method was successfully used to identify the source of bloodmeals in all feeding I. ricinus ticks and in half of questing field-collected L ricinus ticks. Moreover, the bloodmeal source was identified in 65% of ticks infected with B. burgdorferi sensu lato. Further development of this technique may be envisaged for the detection of other vector-borne patbogens and their reservoir hosts.
  • Publication
    Métadonnées seulement
    Detection and identification of Ehrlichia spp. in ticks collected in Tunisia and Morocco
    (2005)
    Sarih, M'Hammed
    ;
    M'Ghirbi, Youmna
    ;
    Bouattour, Ali
    ;
    Gern, Lise 
    ;
    Baranton, Guy
    ;
    Postic, Danièle
    A broad-range 16S rRNA gene PCR assay followed by partial sequencing of the 16S rRNA gene was used for the detection of members of the family Anaplasmataceae in ticks in North Africa. A total of 418 questing Ixodes ricinus ticks collected in Tunisia and Morocco, as well as 188 Rhipicephalus ticks from dogs and 52 Hyalomma ticks from bovines in Tunisia, were included in this study. Of 324 adult L ricinus ticks, 16.3% were positive for Ehrlichia spp., whereas only 3.4 and 2.8% of nymphs and larvae, respectively, were positive. A large heterogeneity was observed in the nucleotide sequences. Partial sequences identical to that of the agent of human granulocytic ehrlichiosis (HGE) were detected in L ricinus and Hyalomma detritum, whereas partial sequences identical to that of Anaplasma platys were detected in Rhipicephalus sanguineus. However, variants of Anaplasma, provisionally designated Anaplasma-like, were predominant in the L ricinus tick population in Maghreb. Otherwise, two variants of the genus Ehrlichia were detected in L ricinus and H. detritum. Surprisingly, a variant of Wolbachia pipientis was evidenced from L ricinus in Morocco. These results emphasized the potential risk of tick bites for human and animal populations in North Africa.
  • Publication
    Métadonnées seulement
    Entomologic and serologic evidence of zoonotic transmission of Babesia microti, eastern Switzerland
    (2002)
    Foppa, Ivo M
    ;
    Krause, Peter J
    ;
    Spielman, Andrew
    ;
    Goethert, Heidi
    ;
    Gern, Lise 
    ;
    Brand, Brigit
    ;
    Telford, Sam R
    We evaluated human risk for infection with Babesia microti at a site in eastern Switzerland where several B. microti-infected nymphal Ixodes ricinus ticks had been found. DNA from pooled nymphal ticks amplified by polymerase chain reaction was highly homologous to published B. microti sequences. More ticks carried babesial infection in the lower portion of the rectangular 0.7-ha grid than in the upper (11% vs. 0.8%). In addition, we measured seroprevalence of immunoglobulin (Ig) G antibodies against B. microti antigen in nearby residents. Serum from 1.5% of the 396 human residents of the region reacted to B. microti antigen (greater than or equal to1:64), as determined by indirect immunofluorescence assay (IgG). These observations constitute the first report demonstrating B. microti in a human-biting vector, associated with evidence of human exposure to this agent in a European site.