Amino Acid Requirement for the Propagation of Vaccinia Virus in Earle's L Cells

Using Earle's L cells, the amino acid requirement for the propagation of vaccinia virus was found to coincide with the amino acids found by Eagle (Eagle, 1955; Eagle et al. 1956) to be essential for the L cells themselves. There was no evidence that vaccinia virus particles harbour enzymes involved in amino acid synthesis.