Abstract: Based on loop-mediated isothermal amplification (LAMP), a sensitive, specific, low-cost, visual and trace method was developed using a capillary as the reaction medium for the detection of the toxin genes tdh and trh of Vibrio parahaemolyticus. Six primer pairs were designed targeting either of the toxin genes. The concentrations of Mg2＋, dNTPs and Bst DNA polymerase, reaction time and temperature were optimized for the capillary LAMP (cLAMP) method. The sensitivity and specificity of the method were evaluated. The results indicated that optimum conditions of the cLAMP method were as follows: magnesium ion concentration 6 or 8 mmol/L dNTPs cocnetration 1.44 or 1.28 mmol/L, Bst DNA polymerase concentration 0.096 U/L (in a volume of 5 μL), reaction temperature, 65 ℃, and time, 60 min. The limits of detection (LODs) of the tdh and trh genes were 3 and 34 fg/μL for genomic DNA, and 9.85 × 103 and 8.25 × 105 CFU/mL for bacterial culture, respectively. No cross-reactivity was observed with other common bacterial pathogens, including cholera, V. vulnificus, V. alginolyticus, Aeromonas hydrophila, Escherichia coli, and Staphylococcus aureus. The results in this study provide technical support for the development of visual and trace detection kits for the foodborne pathogen V. parahaemolyticus.

Key words: Vibrio parahaemolyticus, toxin-encoding genes, capillary loop-mediated isothermal amplification, visual detection, trace detection