To establish a rapid, convenient and robust method for detecting the infection titer of Sendai virus (Sev) vectors.

With transmission-defective Sendai virus vector as the research target and flow cytometry as the detection method, a mathematic model based on Poisson's distribution was established, and the infection titer was determined by one parameter of the mathematic model after curve-fitting.

An innovative method for detecting the infection titer of Sendai virus vector was successfully established. There were no significant differences between the results obtained from the flow cytometry method and traditional immunofluorescence method, and the flow cytometry method displayed good reproducibility [infection titer is (2.13±0.05)×10⁹ IU·mL^-1, RSD is 2.34%].

The infection titer detection is an important quality control item of viral vector gene therapy products and the traditional methods such as plaque method, TCID₅₀ method and immunofluorescence method have the disadvantages of long experiment cycle, bad reproducibility and poor objectivity. This study is of significance to be a representative quality control reference for infection titer detecting of other viral vectors.