Biotechnological system for the search of substances with potential activity against coronaviruses

Aim. Development of a biotechnological system based on a non-pathogenic coronavirus strain for humans and a sensitive cell line to the selected strain aimed at identifying compounds with potential antiviral activity. Methods. The study was conducted on the cell lines CEF, CEFs, and ВНК-21, which are sensitive to the avian infectious bronchitis virus (IBV). Cell cultivation was performed in flasks and microplates with adhesive surfaces at 37 C in a 5% CO2 atmosphere. To detach the cells from the growth surface, a Versene solution (0.02%) was used, and for trypsinization of CEF, a trypsin solution (0.25%) was applied. Growth media for all cell cultures were prepared based on a mixture of RPMI-1640 and DMEM in a 1:1 ratio, supplemented with 5% fetal serum. Results. The adaptation of the model virus IBV strain H120 to cultivation in ВНК-21 cell cultures was carried out using intermediate CEF and CEFs cultures. In ВНК-21 cells, IBV induced a pronounced cytopathic effect and demonstrated high infectious titers, reaching 5.5 lg TCID50/mL. The use of intermediate CEF and CEFs cell cultures facilitated the gradual adaptation of the virus to the new cultivation conditions due to the antigenic affinity between chicken embryo fibroblast cells and avian embryos. Conclusions: As a result of the conducted research, the vaccine virus IBV H120 was successfully adapted to cultivation conditions in ВНК-21 cell cultures, using primary trypsinized chicken embryo fibroblast cells as an intermediate system. The obtained system “ВНК-21 cell culture + IBV H120”, cultivated at 37 C in a 5% CO2 atmosphere, can be recommended for use in further biotechnological and virological studies, particularly for evaluating the antiviral activity of potential drugs against coronaviruses.