Application of a Serum-Free Medium for the Growth of Vero Cells and the Production of Reovirus

Two strains of reovirus (serotype 1 Lang/TIL and serotype 3 Dearing/T3D) were propagated in Vero cells grown in stationary or agitated cultures in a serum-free medium, M-VSFM. Solid microcarriers (Cytodex-1) were used to support cell growth in agitated cultures with a normal doubling time of 25 h. Cell yields of 1 * 10^6 cells/ mL were obtained from an inoculum of 2 * 10^5 cells/mL in 4 days in microcarrier cultures. The growth profile and cell yield was not significantly different from serumsupplemented cultures. The virus titer increased by 3-4 orders of magnitude over a culture period of 150 h. The maximum virus titer in stationary cultures reached > 1 * 10^9 pfu/mL for both strains of reovirus in M-VSFM. M-VSFM also supported high viral yields in microcarrier cultures. Both the specific productivity and final viral yield was higher in M-VSFM than serum-supplemented cultures. The high viral productivity suggests that this is a suitable system for the production of reovirus as an oncolytic agent for human therapeutic use.