Abstract: A rapid assay for detecting avian infectious bronchitis virus was established and laid the foundation for further study on new methods of vaccine potency testing and quality control. Primers and probe of fluorescence quantitative PCR were designed for H52 strain, according to the N gene of IBV. Then the method was optimized. Specificity, sensitivity, and repeatability were tested and the correlation was explored between the quantitative RT-PCR method and EID₅₀ on the determination of virus quntity. In addition, in vitro transcription technology was used to develop a quantitative PCR format with virus copies amount. It was highly specific and no cross-reactions were found with other avian pathogens. The assay had a detection limit of 5.60×10¹ copies/μL viral RNA, which was 10 times more sensitive than the conventional PCR. Coefficient of variation value ranged from 0.9% to 3.2% in repeatability test. Compared with EID₅₀ test results, the correlation coefficient r was 0.934, which showed that two methods in detecting the virus titer on the H52 strain had a good correlation. This assay of TaqMan-MGB fluorescence quantitative RT-PCR is suitable for rapid and quantitative detection of IBV H52 strain.

Key words: luorescence quantitative RT-PCR; TaqMan-MGB probe; avian infectious bronchitis virus; H52