| 41. |
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| 42. |
- Nilsson, Kenneth, et al.
(författare)
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Characterization of a spotted fever group Rickettsia from Ixodes ricinus ticks in Sweden
- 1997
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 35:1, s. 243-247
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Tidskriftsartikel (refereegranskat)abstract
- A spotted fever group rickettsia isolated from the common tick, Ixodes ricinus, was genetically characterized by PCR and genomic sequencing. This study was performed with nymphal and adult ticks collected in southern and central Sweden. I. ricinus is the only North European tick species of medical importance which is regularly collected from humans. No species of the genus Rickettsia has previously been found in Scandinavian ticks, nor has any case of domestic rickettsial infection in humans or animals been reported. According to the nucleotide sequencing, the present Rickettsia sp. belongs to the spotted fever group of rickettsiae. Ticks are the most common arthropod reservoirs and vectors of the rickettsiae of this group. Among 748 ticks investigated, 13 (1.7%) were positive for a Rickettsia sp. Borrelia burgdorferi was detected in 52 (7%) of the ticks, a prevalence similar to or somewhat lower than that previously been recorded in other Swedish studies. There was no evidence of ehrlichial or chlamydial DNA in these ticks. The Rickettsia sp. was further characterized by 16S ribosomal DNA (rDNA) sequencing and restriction fragment length polymorphism (RFLP). The 16S rDNA sequencing resulted in a sequence identical to that described for Rickettsia helvetica, but the pattern obtained with RFLP of the citrate synthetase gene diverged from previously known patterns. The rickettsial agent of one tick which was positive by PCR was confirmed by transmission electron microscopy. The morphology of this rickettsia was similar to that of the spotted fever and typhus group rickettsiae. This represents the first documented isolate of a Rickettsia sp. from Swedish ticks.
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| 43. |
- Norder, Heléne, et al.
(författare)
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Confirmation of nosocomial transmission of hepatitis C virus by phylogenetic analysis of the NS5-B region
- 1998
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 36:10, s. 3066-3069
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Tidskriftsartikel (refereegranskat)abstract
- Four hepatitis C virus transmission chains at three dialysis units were disclosed by limited sequencing; three of these were disclosed by analysis of the NS5-B region of the genome. Dialysis on the same shift as that during which infected patients were dialyzed was the common factor for seven patients in two chains. Two nurses exposed to needle sticks and their sources of infection constituted two other chains. The strains of three chains belonged to subtype 1a and formed clusters with an intrachain variability of 0 to 6 nucleotides compared to 8 to 37 nucleotides for unrelated strains within this subtype. The clusters were supported by bootstrap values ranging from 89 to 100%.
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| 44. |
- ODEBERG, J, et al.
(författare)
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Dynamic analysis of heterogeneous hepatitis C virus populations by direct solid-phase sequencing
- 1995
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Ingår i: Journal of clinical microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 33:7, s. 1870-1874
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, we used a semiautomated solid-phase direct sequencing method to analyze sequence diversity and variation of the hypervariable E2/NS1 region in the hepatitis C virus (HCV) genome in isolates from patients seropositive for HCV. A total of 24 isolates of various origins were sequenced. Six of the patients, not subject to any antiviral therapy, were monitored longitudinally, and rapid sequence variations were observed over a period of 14 months. The nucleotide change rate was found to be 0.1 to 0.2 nucleotide substitution per genome site per year. Furthermore, isolates from five of the patients were used for a comparative study of the direct solid-phase sequencing approach versus the frequently used approach of sequencing individual reverse transcriptase PCR clones. The advantage of direct solid-phase sequencing for studying dynamic changes in heterogeneous populations of HCV is discussed.
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| 45. |
- Olofsson, Anders, et al.
(författare)
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Unusual, high genetic diversity of Aleutian mink disease virus
- 1999
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 37:12, s. 4145-4149
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Tidskriftsartikel (refereegranskat)abstract
- The genetic diversity of Aleutian mink disease virus (AMDV) was examined. Sequences obtained from 35 clinical samples were compared with five published sequences. An unusual, high genetic variability was revealed. Three phylogenetic subgroups of AMDV were identified, and the presence of more than one genotype at some farms was detected
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| 46. |
- OLSEN, B, et al.
(författare)
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TRANSHEMISPHERIC EXCHANGE OF LYME-DISEASE SPIROCHETES BY SEABIRDS
- 1995
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Ingår i: JOURNAL OF CLINICAL MICROBIOLOGY. - : AMER SOC MICROBIOLOGY. - 0095-1137. ; 33:12, s. 3270-3274
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Lyme disease is a zoonosis transmitted by ticks and caused by the spirochete Borrelia burgdorferi sensu late. Epidemiological and ecological investigations to date have focused on the terrestrial forms of Lyme disease. Here we show a significant role for
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| 47. |
- Olsen, Björn, et al.
(författare)
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Transhemispheric exchange of Lyme disease spirochetes by seabirds
- 1995
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Ingår i: Journal of Clinical Microbiology. - Washington, DC, United States : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 33:12, s. 3270-3274
-
Tidskriftsartikel (refereegranskat)abstract
- Lyme disease is a zoonosis transmitted by ticks and caused by the spirochete Borrelia burgdorferi sensu lato. Epidemiological and ecological investigations to date have focused on the terrestrial forms of Lyme disease. Here we show a significant role for seabirds in a global transmission cycle by demonstrating the presence of Lyme disease Borrelia spirochetes in Ixodes uriae ticks from several seabird colonies in both the Southern and Northern Hemispheres. Borrelia DNA was isolated from I. uriae ticks and from cultured spirochetes. Sequence analysis of a conserved region of the flagellin (fla) gene revealed that the DNA obtained was from B. garinii regardless of the geographical origin of the sample. Identical fla gene fragments in ticks obtained from different hemispheres indicate a transhemispheric exchange of Lyme disease spirochetes. A marine ecological niche and a marine epidemiological route for Lyme disease borreliae are proposed.
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| 48. |
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| 49. |
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| 50. |
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