Stability of freeze-dried DNA vaccine against dental caries

Objective: To observe the stability of freeze-dried DNA vaccine against dental caries at stage of pilot production. Methods: Three batches of DNA vaccine against dental caries prepared during pilot production were stored at -70°C for 16 months, then observed for appearance and determined for reconstitution time, moisture content, pH value after reconstitution and proportion of supercoiled plasmids every 2 months. Results: During a period of 16 months, the freeze-dried vaccine looked like a crisp cake, of which the reconstitution time, moisture content, pH value and proportion of supercoiled plasmids were less than 1 min, less than 3%, 7.30-7.46 and 85.02%-97.15% respectively, while the various indexes met the relevant requirements, and the stability was high. Conclusion: All the indexes of freeze-dried DNA vaccine against dental caries met the requirements in Technical Guideline for Pre-clinical Study on Prophylactic DNA Vaccines, and the quality was stable.