CELLS BY YEAST EXTRACT

IT is not always appreciated that the composition of the medium and the conditions of incubation may profoundly influence the morphology of cells in tissue culture, the rate of virus multiplication and the nature of any cytopathic effect produced. Thicke et al. (1952) showed that multiplication of poliovirus in tissue culture was greater with Medium “ 199 ” than with Hanks ’ solution and ox serum ultrafiltrate. A maintenance medium containing serum and embryonic extract produced a higher yield of herpes simplex virus than did a medium containing serum ultrafiltrate (Scherer, 1953). Melnick and Riordan (1952) noted that cysteine increased the final titre of poliovirus in monkey kidney cells, whereas glycine had the opposite effect; Hanks ’ solution and cysteine gave a greater yield of virus than any other medium they used. Reissig, Black and Melnick (1956) found that in a medium containing serum, embryonic extract and amniotic fluid, human carcinoma (H.Ep.2) cells infected with measles virus underwent syncytium or giant-cell formation, like that described by Enders and Peebles (1954) in human renal cell cultures. However, when glutamine was added to the medium an elongated, fibroblast-like configuration of the indi