Validation of a test procedure for determination of specific activity of human recombinant interferon beta (Infibeta®) using various cell/virus combinations

Interferon beta preparations have demonstrated efficacy in the treatment of multiple sclerosis. One of the most important quality attributes that support efficacy and safety of interferon beta preparations is specific antiviral activity. Interferon beta activity is determined by the biological test method which can lead to an erroneous final result due to the system uncertainties that contribute to the overall uncertainty. Accurate assessment of specific activity plays an important role in adequate determination of the product’s therapeutic dose, therefore the test method standardisation and validation are of particular relevance. The aim of the study was to validate a test procedure for assessing specific activity of human recombinant interferon beta preparations, using various cell/virus combinations, as illustrated by the example of Infibeta ® . Materials and methods: WISH, Vero, A-549, and MDBK cells in combination with mouse encephalomyocarditis virus were used in the study. The testing was performed using the biological test method based on the interferon ability to suppress virus-induced cytopathic effects in cell cultures. The results were processed using methods of mathematical statistics and the GraphPadPrism, Statistical 2/0 software package. Results: the paper compares the results of specific activity determination of Infibeta ® (interferon beta-1b) using various cell/virus combinations. The dose-response curves were used to compare the test results. It was demonstrated that all the tested cell lines could be used in the biological test procedure for determination of interferon beta specific activity. However, the best results were obtained with A-549, WISH cells in combination with mouse encephalomyocarditis virus. The following validation characteristics were determined in the cell/virus systems: specificity, linearity, precision, and robustness. Conclusions: the study validated the test procedure that enables measurement of interferon beta specific activity in the range of 4.8–11.2 IU/mL at a satisfactory accuracy level, which guarantees reliable test results. The study demonstrated robustness, intermediate precision, and reproducibility of the test procedure.