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Aeschlimann, André
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Aeschlimann, André
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Professeur honoraire
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audrey.aeschlimann@unine.ch
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- PublicationAccès libreConfirmation that Rickettsia helvetica sp. nov. Is a Distinct Species of the Spotted Fever Group of Rickettsiae(1993)
; Raoult, DidierWe propose the name Rickettsia helvetica sp. nov. for a rickettsial serotype of unknown pathogenicity isolated in 1979 in Switzerland from Ixodes ricinus ticks and designated the Swiss agent. The growth characteristics and the results of microimmunofluorescence serologic typing, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting (immunoblotting) with specific mice sera, and a polymerase chain reaction followed by restriction fragment length polymorphism analysis confirmed previously reported preliminary findings which suggested that this rickettsia, to which a name was given provisionally, does represent a new member of the spotted fever group of rickettsiae. The type strain is C3 (Reference Center for Rickettsioses, Marseille, France). - PublicationAccès libreIxodes (Pholeoixodes) hexagonus, an efficient vector of Borrelia burgdorferi in the laboratory(1991)
; - PublicationAccès libreChanges in the protein profile and antigenicity of different Borrelia burgdorferi strains after reintroduction to Ixodes ricinus ticks
; Eight Swiss strains of Borrelia burgdorferi, with various protein profiles and the North-American strain B31 were artificially introduced into Ixodes ricinus ticks and reisolated 10 days later. All isolates were subsequently examined by SDS-PAGE analysis. Comparing initial isolates with the reisolates, we observed that 7 out of 9 strains changed their protein pattern with respect to the major proteins OspA, OspB and the 22 kDa protein after passage in the tick. The strains NE2, NE4 and NE83 with the initial phenotype of OspA and 22 kDa proteins changed to the phenotype of OspA and OspB, the strains B2 and NE202 with the initial phenotype of OspA acquired an additional protein of 22 kDa and the strain NE58 with the initial phenotype of OspA also acquired a protein of 22 kDa. Examination of these isolates by Western blot analysis demonstrated that the reaction with the monoclonal antibody H5332 and a monospecific polyclonal antibody PoAb/anti-22 kDa differed between the initial isolates and the reisolates. - PublicationAccès libreRickettsia-like microorganisms in the ovarian primordial of molting Ixodes ricinus (acari : ixodidae) larvae and nymphs
; Un grand nombre de micro-organismes de type rickettsien ont été observés dans les cellules des ébauches ovariennes de larves et de nymphes d'Ixodes ricinus, lors de la mue. La morphologie de ces organismes est identique chez toutes les tiques examinées. Ils mesurent 0,3-0,4 µm de diamètre et 0,6-1,3 µm, parfois jusqu’à 2,5 µm, de long. Ils possèdent une paroi externe membraneuse fortement ondulée et une membrane plasmique interne. L’épaisseur de chacune de ces 2 structures est de 6-10 nm. Les microorganismes sont toujours inclus, soit seuls soit en groupe, dans des vacuoles contenues dans le cytoplasme de la cellule hôte, dans des mitochondries vacuolées, ou dans des vacuoles dont les parois sont constituées en partie de restes de mitochondrie. Plus les ovaires des nymphes sont développés, plus le nombre de micro-organismes associés aux mitochondries augmente. La relation entre les microorganismes et les mitochondries est discutée, la morphologie des gonades chez les tiques immatures est décrite., A large number of coccoid, or oval to spindle-shaped rickettsialike microorganisms are detected intracellularly within the primordial ovaries of all examined molting larvae and nymphs, descendants of a female Ixodes ricinus collected in a forest near Neuchâtel, Switzerland, and within all molting nymphal I. ricinus captured as starved ticks in the same area. The morphology of the microorganisms is identical in all ticks. They measure 0.3-0.4 µm in diameter and 0.6-1.3 µm, occasionally up to about 2.5 µm in length. The microorganisms possess a highly rippled membranous outer cell wall and an inner plasma membrane. Both cellular boundaries show a thickness of approximately 6-10 nm. The microorganisms are always enclosed, singly or in groups, within membrane limited vacuoles of host cells, within vacuolated mitochondria, or within vacuoles with their wall consisting partially of a deformed mitochondrion and partially of a plasma membrane of host cells. With the advance of the development of the nymphal ovaries, the groups of microorganisms associated with mitochondria become larger and increase in number, and they are dominant within the posterior part of the organs in the nymphs examined at day 21 after repletion. The relationship between the microorganisms and the mitochondria is discussed. The morphology of the gonads of the examined immature ticks is also described. - PublicationAccès libreLongitudinal study of Lyme borreliosis in a high risk population in Switzerland
; ; - PublicationAccès libreInfection of field-collected Ixodes ricinus (Acari: Ixodidae) larvae with Borrelia burgdorferi in Switzerland
; Free-living larvae from natural areas in five regions in Switzerland were collected to determine the infection rate of Ixodes ricinus L. larvae by Borrelia burgdorferi Johnson. Larvae were examined for the spirochetes using direct fluorescent antibody assay. Of 652 larvae examined, spirochetes were detected in 20 (3.1%). No differences in infection rate among sites were detected. The low prevalence of B. burgdorferi in larvae, compared with higher infection rate in nymphs (12.8%) and adults (14.5%), suggests that transovarial transmission is inefficient. These results suggest that I. ricinus can serve as a reservoir for B. burgdorferi in nature. Further study is needed on the relative importance of ticks, compared with mammals and birds, as reservoirs for B. burgdorferi.