Rapid and sensitive detection of Listeria ivanovii by loop-mediated isothermal amplification of the smcL gene

PLoS One. 2014 Dec 30;9(12):e115868. doi: 10.1371/journal.pone.0115868. eCollection 2014.

Abstract

A loop-mediated isothermal amplification (LAMP) assay for rapid and sensitive detection of the L. ivanovii strains had been developed and evaluated in this study. Oligonucleotide primers specific for L. ivanovii species were designed corresponding to smcL gene sequences. The primers set comprise six primers targeting eight regions on the species-specific gene smcL. The LAMP assay could be completed within 1 h at 64°C in a water bath. Amplification products were directly observed by the Loopamp Fluorescent Detection Reagent (FD) or detected by agarose gel electrophoresis. Moreover, the LAMP reactions were also detected by real-time measurement of turbidity. The exclusivity of 77 non-L. ivanovii and the inclusivity of 17 L. ivanovii were both 100% in the assay. Sensitivity of the LAMP assay was 250 fg DNA and 16 CFU per reaction for detection of L. ivanovii in pure cultures and simulated human stool. The LAMP assay was 10 and 100-fold more sensitive than quantitative PCR (qPCR) and conventional PCR assays,respectively. When applied to human stool samples spiked with low level (8 CFU/0.5 g) of L. ivanovii strains, the new LAMP assay described here achieved positive detection after 6 hours enrichment. In conclusion, the new LAMP assay in this study can be used as a valuable, rapid and sensitive detection tool for the detection of L. ivanovii in field, medical and veterinary laboratories.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Feces / microbiology
  • Genes, Bacterial
  • Humans
  • Listeria / genetics*
  • Listeria / isolation & purification
  • Listeriosis / diagnosis*
  • Listeriosis / microbiology
  • Molecular Sequence Data
  • Nucleic Acid Amplification Techniques*
  • Sensitivity and Specificity
  • Virulence Factors / chemistry
  • Virulence Factors / genetics

Substances

  • Virulence Factors

Grants and funding

This work was supported by grants (Mega Project of Research on The Prevention and Control of HIV/AIDS, Viral Hepatitis Infectious Diseases 2011ZX10004-001, 2013ZX10004-101 to Changyun Ye) from the Ministry of Science and Technology, People’s Republic of China. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.