Development of Low-Serum Culture Media for the in Vitro Cultivation of Theileria annulata S15 Cell Line

Background: The production of bovine theileriosis vaccine involves in vitro cultivation of Theileria annulata schizont-infected cell lines. Fetal bovine serum (FBS) is commonly used in animal cell culture, including the Theileria cell line. However, we aimed to reduce the amount of serum needed for cell culture by modifying the Stoker culture medium with supplements such as excretion factor and serum substitutes. Methods: To evaluate the effectiveness of these modifications, techniques such as cell counting, cell viability assays, and genomic analysis were employed in the Parasitic Vaccines Production Department of Razi institute of Iran, from 2020 to 2022.  Statistical analysis was used to compare the results of different experimental conditions.  Results: The three experimental media were as effective as the commonly used 10% Stoker medium in supporting the growth and viability of cells. Conclusion: The significant reduction in the required amount of serum and the remarkable cell growth achieved by using defined serum replacements for the production of cell culture media is a significant step towards the preparation of a proper cell culture medium for the production of bovine Theileriosis vaccine.