Development of a duplex real-time TaqMan PCR assay with an internal control for the detection of Mycoplasma gallisepticum and Mycoplasma synoviae in clinical samples from commercial and backyard poultry

Abstract

In this study, we report the development and validation of a duplex real-time polymerase chain reaction (PCR) assay with an internal control using TaqMan-labelled probes for the detection of Mycoplasma gallisepticum and Mycoplasma synoviae (duplex MGMS PCR). The MGMS PCR was highly specific with a sensitivity of 7 and 1 colony-forming units/ml for M. gallisepticum and M. synoviae, respectively, using dilution of pure culture that corresponds to 34 and 29 DNA copies per reaction. Validation of the assay was completed with 260 and 27 pooled samples (tracheal swabs) from commercial chickens and turkeys, respectively, with potential M. gallisepticum and M. synoviae involvement and 42 samples (palatine cleft swabs) from backyard geese and ducks. Using isolation as the gold standard, the MGMS PCR was more sensitive than isolation and the analytical sensitivity was 0.944 and 0.958 for M. gallisepticum and M. synoviae, respectively. In comparison with a gapA-based assay (gapA PCR) and a 16S rRNA-based assay (16S PCR) for M. gallisepticum and M. synoviae, respectively, the results agreed for 94.5% and 96.6%, respectively. The use of the internal control allowed monitoring of proper extraction and inhibition of amplification that was detected in 12 samples. The duplex MGMS PCR was shown to be superior to the presently reported real-time PCR assays in terms of combination of sensitivity, specificity and capacity of detection of more than one target in a single tube. In conclusion, the duplex MGMS PCR was highly specific, sensitive, and reproducible and could be used on clinical samples from commercial chickens, turkeys and backyard poultry including ducks and geese.

Acknowledgements

This research was supported by the ISTC grant #3017 of ARS USDA. The authors thank Dr Jeff Evans for reading the manuscript. They are also grateful to the backyard farmers of Vladimir region for providing flocks for sampling.