Dataset Information

Detection of Francisella tularensis in ticks and identification of their genotypes using multiple-locus variable-number tandem repeat analysis.

ABSTRACT: BACKGROUND: Tularemia was reported in China over 50 years ago, however, many epidemical characteristics remain unclear. In the present study, the prevalence of Francisella tularensis in ticks was investigated during an epidemiological surveillance in China and then we measured their genetic diversity by conducting multiple-locus variable- number tandem repeat analysis (MLVA). RESULTS: 1670 ticks from 2 endemic areas (Inner Mongolia Autonomous Region and Heilongjiang Province) and 2 non-endemic areas (Jilin and Fujian Provinces) were collected and tested for evidence of tularemia by nested PCR. The prevalence of Francisella tularensis in ticks averaged 1.98%. The positive rates were significantly different among tick species, with Dermacentor silvarum and Ixodes persulatus responsible for all positive numbers. All F. tularensis that were detected in ticks belonged to F. tularensis subsp. holarctica and MLVA disclosed genetic diversity. One subtype was identified in 17 of 33 positive tick samples in three different study areas. Another subtype belonging to F. tularensis subsp. holarctica genotype was described for the first time in the current study. CONCLUSION: The study showed two tick species, D. silvarum and I. persulatus harboring the pathogen of tularemia in natural environment, indicating these two tick species might have a role in tularemia existence in China. MLVA results disclosed the genetic diversity F. tularensis and identified one genotype as the most prevalent among the investigated ticks in China.

SUBMITTER: Zhang F

PROVIDER: S-EPMC2567983 | biostudies-literature | 2008

REPOSITORIES: biostudies-literature

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Detection of Francisella tularensis in ticks and identification of their genotypes using multiple-locus variable-number tandem repeat analysis.

Zhang Fang F Liu Wei W Wu Xiao-Ming XM Xin Zhong-Tao ZT Zhao Qiu-Min QM Yang Hong H Cao Wu-Chun WC

BMC microbiology 20080917

<h4>Background</h4>Tularemia was reported in China over 50 years ago, however, many epidemical characteristics remain unclear. In the present study, the prevalence of Francisella tularensis in ticks was investigated during an epidemiological surveillance in China and then we measured their genetic diversity by conducting multiple-locus variable- number tandem repeat analysis (MLVA).<h4>Results</h4>1670 ticks from 2 endemic areas (Inner Mongolia Autonomous Region and Heilongjiang Province) and 2 ...[more]

PMID: 18798995

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Project description:BACKGROUND: Since Francisella noatunensis was first isolated from cultured Atlantic cod in 2004, it has emerged as a global fish pathogen causing disease in both warm and cold water species. Outbreaks of francisellosis occur in several important cultured fish species making a correct management of this disease a matter of major importance. Currently there are no vaccines or treatments available. A strain typing system for use in studies of F. noatunensis epizootics would be an important tool for disease management. However, the high genetic similarity within the Francisella spp. makes strain typing difficult, but such typing of the related human pathogen Francisella tullarensis has been performed successfully by targeting loci with higher genetic variation than the traditional signature sequences. These loci are known as Variable Numbers of Tandem Repeat (VNTR). The aim of this study is to identify possible useful VNTRs in the genome of F. noatunensis. RESULTS: Seven polymorphic VNTR loci were identified in the preliminary genome sequence of F. noatunensis ssp. noatunensis GM2212 isolate. These VNTR-loci were sequenced in F. noatunensis isolates collected from Atlantic cod (Gadus morhua) from Norway (n = 21), Three-line grunt (Parapristipoma trilineatum) from Japan (n = 1), Tilapia (Oreochromis spp.) from Indonesia (n = 3) and Atlantic salmon (Salmo salar) from Chile (n = 1). The Norwegian isolates presented in this study show both nine allelic profiles and clades, and that the majority of the farmed isolates belong in two clades only, while the allelic profiles from wild cod are unique. CONCLUSIONS: VNTRs can be used to separate isolates belonging to both subspecies of F. noatunensis. Low allelic diversity in F. noatunensis isolates from outbreaks in cod culture compared to isolates wild cod, indicate that transmission of these isolates may be a result of human activity. The sequence based MLVA system presented in this study should provide a good starting point for further development of a genotyping system that can be used in studies of epizootics and disease management of francisellosis.

Dataset Information

Detection of Francisella tularensis in ticks and identification of their genotypes using multiple-locus variable-number tandem repeat analysis.

Publications

Detection of Francisella tularensis in ticks and identification of their genotypes using multiple-locus variable-number tandem repeat analysis.

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