Differential requirements of two insect cell lines for growth in serum-free medium.

The development of a serum-free medium that supports the growth of cells from a Spodoptera frugiperda and a Lymantria dispar cell line is reported. A yeast hydrolysate provided the B-vitamin complex, and a combination of a meat hydrolysate and tryptose provided most of the free amino acids required for cell growth. Supplemental cystine and methionine were required to achieve maximum cell growth. The serum or serum replacements used in earlier formulations were replaced with commercial lipid preparations and increased levels of iron salts. Although the cell growth cycle had a somewhat extended lag phase and the population doubling time of the S. frugiperda cells was longer than on serum-containing medium, the saturation densities were much higher. Spodoptera cells grown in this medium replicated the Autographa californica nuclear polyhedrosis virus well, producing 8.71 x 10(6) TCID50 extracellular virus and 4.4 x 10(6) polyhedra/ml culture. The specific activity of the polyhedra was somewhat less than that of polyhedra produced in insects.