ABSTRACT
Objective:To construct a droplet digital PCR (ddPCR) for quantification of virus particles in recombinant adenovirus-vectored SARS-CoV-2 vaccine.Methods:The genome of SARS-CoV-2 BA.1 strain was used as the target gene. A set of primer and probe was designed based on the conserved sequence of spike protein, and the ddPCR for quantification of virus particles in recombinant adenovirus-vectored SARS-CoV-2 vaccine was established. The linearity, accuracy, specificity, repeatability and durability of the method were verified.Results:The optimal annealing temperature for ddPCR was 63℃. When the number of virus particles was in the range of 5×10 5-2×10 7 VP/ml, the linearity and the recovery rate of the method were good; the specificity of the probe and primer was good; the coefficient of variation (CV) values of the repeatability and the intermediate precision were within 10%; the CV value of the durability was within 15%. When comparing ddPCR with qPCR, the CV values were all within 10%. Conclusions:The established ddPCR had high sensitivity, good stability and strong specificity, suggesting that it could be used for the quantitative detection of virus particles in recombinant adenovirus-vectored SARS-CoV-2 vaccine.