Growth of pathogenic virus in a large-scale tissue culture system

A model system is described for the mass propagation of Rift Valley fever (RVF) virus, utilizing large-volume fermentor units for suspension culture of tissue cells and the subsequent production of virus. Comparisons between laboratory- and fermentor-scale operations of tissue cell growth gave equivalent results. Cell viability dropped 24 to 30 hr postinfection with a subsequent virus yield between 10(8.0) and 10(9.0) mouse intracerebral median lethal doses per milliliter. Infecting volumes of tissue cell culture (20- or 40-liter working volumes) had no apparent effect on virus yields. Tissue cells grown under either oxidation-reduction potential- and pH-controlled or uncontrolled conditions showed little or no difference in their ability to produce RVF virus. We believe this tissue cell virus process to have potential application for large-scale production of vaccines for human or veterinary use or for the mass propagation of certain carcinogenic viruses for cancer research, once use of established lines for this purpose is accepted.