Establishment of TaqMan real-time quantitative PCR assay based on vvhA gene for quick detection of Vibrio vulnificus / 中华急诊医学杂志

ABSTRACT

Objective To establish a TaqMan real-time fluorescent quantitative PCR to detect Vibrio vulnificus based on hemolysin gene(vvhA)that coding cytolysin.Method By using software Primer Express, the PCR primers and TaqMan probe,which located in the conserved region of vvhA gene sequence,were designed for establishment of a TaqMan real-time fluorescent quantitative PCR to detect 100 bp amplicon from V.vulnificus DNA.A recombinant plasmid pMD19-vvhA100 as a positive control during detection was constructed using gene cloning technique.Minimal amplification cycles(Ct value)and fluorescence intensity enhancement (△Rn value)were used as observing index to optimize the reaction conditions of the TaqMan real-time fluorescent quantitative PCR.The DNAs with different concentrations from V.vulnificus and other eight bacteria and pMD19- vvhA100 were applied as templates to determine the specificity,sensitivity and reappearance of the TaqMan real- time fluorescent quantitative PCR.ICR mice were intraperitoneally,subcutaneously and orally infected with V. vulnificus,respectively.The detection effect of the TaqMan real-time fluorescent quantitative PCR was measured using the specimens of peripheral blood,subcutaneous tissue and intestinal content collected from the infected mice.Results The established TaqMan real-time fluorescent quantitative PCR showed positive results only for V. vulnificus DNA and pMD19-vvhA100.The detection effectiveness of the TaqMan real-time fluorescent quantitative PCR was as high as 0.01 ng of V.vulnificus DNA or 103 copies of pMD19-vvhA100.The SD values of the detection results repeated for three times using pMD19-vvhA100 with different concentrations were lease than 0.79. The detection results of TaqMan real-time fluorescent quantitative PCR were positive for all the specimens of peripheral blood and subcutaneous tissue.Conclusions The TaqMan real-time fluorescent quantitative PCR established in this study for V.vulnificus vvhA gene detection has advantages such as quickness,stability, sensitivity and specificity,indicating this method can be used for clinical laboratory diagnosis of septicemia and wound infection caused by V.vulnificus.