The influence of cell culture media and their additives on virus inactivation in vitro.

Aim: Comparative inactivation studies with the murine norovirus (MNV) and different test substances showed considerable different results between test laboratories. To decipher the underlying mechanisms of this observation, different virus pools (virus suspensions) of the MNV were analysed in two independent laboratories by performing inactivation tests with i. a. various alcoholic formulations and different culture media. Methods: Virucidal activity of different test formulations (propan-2-ol, propan-1-ol, ethanol, aldehydes and peracetic acid) against MNV has been tested in the quantitative suspension test according to EN 14476:2019. Results: Results of the inactivation studies with MNV varied greatly depending on the cell culture medium and its additives used. In particular, the addition of HEPES to the medium in the course of virus propagation led to a strong decrease in the virus inactivation, when this virus pool was used in the approach with an alcoholic formulation. Conclusion: The use of different cell culture media with individual supplements can have a major impact on the results of inactivation studies with MNV. Therefore, harmonized protocols of viral inactivation test should be developed that describe the same cell culture conditions.