Acta Veterinaria et Zootechnica Sinica ›› 2025, Vol. 56 ›› Issue (9): 4750-4758.doi: 10.11843/j.issn.0366-6964.2025.09.051

• Research Notes • Previous Articles    

Establishment of a Triple TaqMan qPCR Detection Method for Mycobacterium avium subsp. Paratuberculosis

LIU Tian1,2,3(), WU Yulun1,2,3, YAO Huochun1,2,3,*(), PAN Zihao1,2,3,*()   

  1. 1. College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
    2. Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing 210095, China
    3. WOAH Reference Laboratory for Swine Streptococcosis, Nanjing 210095, China
  • Received:2024-11-14 Online:2025-09-23 Published:2025-09-30
  • Contact: YAO Huochun, PAN Zihao E-mail:15170684036@163.com;yaohch@njau.edu.cn;panzihao@njau.edu.cn

Abstract:

Mycobacterium avium subsp. paratuberculosis (MAP) is the pathogen causing Johne's disease in ruminants and brings inestimable economic losses to the global livestock industry every year. Due to the difficulty in treatment, timely diagnosis and early culling of diseased animals are currently the main means of MAP prevention and control. The gold-standard culture detection cycle for MAP is long, while the qPCR technology, which directly detects nucleic acids in samples, can quickly identify the pathogen and is currently widely used. This study aims to establish a triplex TaqMan qPCR method for MAP detection targeting non-insertion sequence (IS) of MAP, which can improve the sensitivity and specificity of detection. Design primer probes for the MAP2765c, F57 and hspX genes in the MAP genome. Taking the MAP strains isolated in this laboratory as a control, a triple qPCR detection system was established. A total of 181 samples of dairy and beef cattle were clinically collected, and a compliance test was carried out using the triple qPCR method and the national standard method (GB/T 27637—2011). The results showed that the sensitivity of the triple qPCR method established in this study could reach 10 copies·μL-1; the coefficient of variation of the repeated results was all less than 5%; in the specificity experiment, only MAP nucleic acid showed an amplification curve; the R2 of the standard curves were all greater than 0.999 and the amplification efficiency was between 97% and 100%; the positive rate of clinical samples detected by the triple qPCR method was 22.65% (41/181), which was higher than that of the national standard method (15.47%), and the detection coincidence rate of the two methods was 76.28% (138/181); according to the detection requirements of the ranch, the samples were classified and analyzed: the detection rates of the national standard method and the triple qPCR method in "high-MAP-risk samples" were 25% (17/68) and 44.12% (30/68) respectively, while the positive rates of the two methods for detecting samples with lower MAP risk were both 9.73% (11/113). The triple qPCR method designed in this study has good sensitivity, specificity and repeatability, high linearity and quantitative accuracy, and can detect MAP more sensitively in high-MAP-risk samples than the national standard method. The research results provide an optimal solution for dairy and beef cattle farms to carry out monitoring, early warning, control and purification of paratuberculosis.

Key words: Johne's disease, Mycobacterium avium subsp. paratuberculosis, qPCR, Triple TaqMan

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