GROWTH OF SELECTED ARBOVIRUSES IN SERUM-FREE SUSPENSION CELL CULTURES

Evidence that cells, grown in serum-free suspension systems, are capable of supporting the growth of Venezuelan equine encephalomyelitis (VEE) and yellow fever viruses to titers that equaled or exceeded other in vitro systems has been obtained. HeLa, L, cat kidney, and chick embryo cell lines were grown in either lactalbumin hydrolyzate (LAH) medium or a chemically defined medium. These media consisted of inorganic salts, vitamins, glucose, and Methocel to which either LAH or 13 or 19 amino acids were added. All cell lines were grown in their respective media for at least a month prior to infection in 100-milliliter serum bottles (30 ml medium per bottle) on a New Brunswick shaker at 35 C. Maximal virus titers of 10 to the 8th power to 10 to the 9th power mouse intracerebral (MIC) LD50 per ml of VEE virus were obtained 24 hours after infection with concomitant cell lysis in the serum-free cultures of all four cell lines grown in lactalbumin hydro-lyzate. Similar results were obtained in cat kidneys, L, and chick embryo cultures grown in media containing 19 amino acids and in L cell cultures grown with 13 amino acids.