An antiviral substance from Penicillium funiculosum. VII. An attempt to determine whether the material responsible for the antipassive immunity effect exhibited by mice injected with helenine is an interferon.

Helenine, NDV, and statolon, all known inducers of interferon in mice, all exerted a marked antiviral effect against Semliki Forest virus. This AV effect was, so far as can be demonstrated, mediated through, the induced interferon. The same three materials also exerted a marked antipassive immunity effect. All the evidence that can be brought to bear indicates that this API effect like the AV effect is mediated through interferon known to be induced by the three materials. If the API effect does indeed have interferon as its basis, this represents a new and totally unsuspected action of interferon.