Abstract: Objective To evaluate the distribution and clearance of therapeutic DNA vaccines in mice Methods A total of 156 C57BL/6N mice were divided into the negative control group, mouse-derived DNA vaccine group and human-derived DNA vaccine group. Mice were given a single intramuscular injection. At 2 h, 24 h, 7 d, 14 d, 28 d and 56 d after administration, the mice were dissected and organs were collected. The distribution of the two DNA vaccines in different organs was detected using the real-time quantitative polymerase chain reaction (qPCR) method. Results After the administration of the mouse-derived DNA vaccine and human-derived DNA vaccine to C57BL/6N mice, the gene copy number peaked at 2 h and was widely distributed across tissues, among which the copy number at the injection site was the highest. Then, the gene copy number in various tissues and organs trended downward. At 14 d after administration, the gene copy number in various tissues and organs was low, with a decrease of approximately 99.9% compared to 24 h. The distribution was consistent between males and females. In blood, the gene copy number was high at 2 h, and by 24 h,the human-derived and mouse-derived DNA vaccine was basically cleared. Conclusion Two hours after intramuscular injection in C57BL/6N mice, the mouse-derived DNA vaccine and human-derived DNA vaccine are widely distributed in various tissues and organs, with the highest distribution at the injection site, and their survival time in the body does not exceed 56 d.

Key words: Therapeutic Vaccine, Human-Derived DNA Vaccine, Mouse-Derived DNA Vaccine, Preclinical Research, Mice, Biodistribution, Real-time Quantitative Polymerase Chain Reaction, Validation of Analytical Procedures