Abstract:A droplet digital polymerase chain (ddPCR) detection method, based on gdh gene of Streptococcus suis was developed to improve the detection and quantification of S. suis. S. suis is an important pathogen, resulting in significant economic losses in pig farming. Prompt detection of S. suis in the field samples is important for effective control. ddPCR is a novel PCR technology, which offers good precision and direct quantification without using calibration curves. In this work, a ddPCR method for the sensitive and accurate quantification of S. suis was established. Under the optimized reaction conditions, results showed that ddPCR was specific to detect S. suis with detection limit of 2.692 copies/μL, and no cross-reactions with Actinobacillus pleuropneumoniae, Haemophilus parasuis, Bacillus subtilis, Escherichia coli, Salmonella, Staphylococcus aureu, Porcine circovirus type2 and Pseudorabies virus. The correlation coefficient (R2) obtained from linear regression analysis showed a good linearity of amplification for ddPCR (R2=0.991), and the repeatability test indicated that the coefficient of variation were 1.66%. The clinical application of ddPCR assay indicated that the sensitive and specific detection method could be useful to standardize quantitative detection of S. suis.
