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Multi-locus Variable-number Tandem-repeat Analysis of the Fish-pathogenic Bacterium Yersinia ruckeri by Multiplex PCR and Capillary Electrophoresis
Published on: June 17, 2019
Characterization of a tandem repeat polymorphism in Rickettsia strains
Liliana Vitorino1, Rita de Sousa1, Fatima Bacellar1
1Universidade de Lisboa, Faculdade de Ciências, Centro de Genética e Biologia Molecular and Instituto de Ciência Aplicada e Tecnologia, Edifício ICAT, Campus FCUL, Campo Grande. 1749-016 Lisboa, Portugal 2CEVDI, Instituto Nacional de Saúde Dr Ricardo Jorge, 2965 Águas de Moura, Portugal.
Mediterranean spotted fever (MSF) is a tick-borne illness caused by Rickettsia conorii. A new VNTR marker, Rc-65, effectively differentiates between Portuguese and Israeli tick typhus strains, aiding rapid identification.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Mediterranean spotted fever (MSF) is a significant tick-borne rickettsiosis.
- Rickettsia conorii complex strains are the causative agents, with R. conorii and Israeli tick typhus (ITT) prevalent in Portugal.
Purpose of the Study:
- To identify and characterize novel genetic markers for differentiating Rickettsia strains.
- To develop a rapid diagnostic tool for distinguishing between Portuguese MSF and ITT isolates.
Main Methods:
- Whole genome sequencing of R. conorii Malish 7 to identify repetitive sequences.
- Design and application of PCR primers for a novel 65 bp tandem repeat (VNTR Rc-65).
- Sequencing and analysis of VNTR Rc-65 alleles in various Rickettsia strains, including Portuguese clinical and vector isolates.
Main Results:
- A novel variable number tandem repeat locus, VNTR Rc-65, was identified.
- VNTR Rc-65 exhibited seven alleles across the studied rickettsial strains with a high diversity index (0.71).
- PCR amplification of VNTR Rc-65 successfully differentiated Portuguese R. conorii Malish-like strains from ITT strains.
Conclusions:
- VNTR Rc-65 is a highly discriminatory genetic marker for Rickettsia strains.
- This marker enables accurate and rapid differentiation between closely related rickettsial pathogens.
- VNTR Rc-65 facilitates improved identification of causative agents of spotted fevers in endemic regions.
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