Effect of serum on the antiviral and anticellular activities of mouse interferon.

Fetal bovine serum markedly decreased the ability of mouse L-929 interferon preparations to inhibit the formation of L-929 clones, but did not affect their ability to inhibit vesicular stomatitis virus (VSV) plaque formation in these cells. This dissociation of effects by interferon preparations indicates that: 1. the mechanism of action of interferon for its anticlonal antiviral activities is different; or 2. the molecule responsible for the anticlonal activity is a separate growth inhibitory factor.