ObjectiveTo establish and verify the verification method of virus inactivation of Sabin strain inactivated poliovirus vaccine (Vero cell)(sIPV).

MethodsPoliovirus types Ⅰ, Ⅱ and Ⅲ were inoculated into Vero cells by a series of gradient dilution, and then amplified by blind cell passage twice. The cytopathic changes were observed, the minimum detection limit of this method and cell sensitivity to virus were explored, and the precision (repeatability and intermediate precision) and applicability of this method were verified.

ResultThe detection limits of the established virus inactivation validation method for poliovirus types Ⅰ, Ⅱ and Ⅲ were -2, -1 and 0 lgCCID ₅₀/mL, respectively. The minimum inoculation concentration of poliovirus types Ⅰ, Ⅱ and Ⅲ to Vero cells was 2 lgCCID ₅₀/mL, and the Vero cell lesions were all observed on day 7 .Thus, the sensitivity of the cell was 2 lgCCID ₅₀/mL. The same inspector repeatedly tested the same batch of samples 6 times, and the test results were consistent. The same batch of samples were tested 6 times by different inspectors at different time, and the test results were consistent. The result of sample stored at -70 °C or below for 7 d was consistent with that of unfrozen sample.The inactivation verification test was carried out on 3 batches of types Ⅰ, Ⅱ and Ⅲ monovalent inactivated virus solution and bulk from sIPV production process, and the inactivation verification test results of the samples tested on the day of sampling and after 7 d of storage at -70 °C or below were consistent, indicating that the precision and applicability of the method were good.

ConclusionThe sIPV virus inactivation validation method effectively detects the inactivation status of the sample, which can be used to evaluate the virus inactivation effect and monitor key steps such as intermediates in the process.