Zinc potentiates the antiviral action of human IFN-alpha tenfold

During the last decade, various zinc salts have been used against the commo n cold syndrome, which is known to be initiated by respiratory viruses, par ticularly rhinoviruses. Using rhinovirus as the challenge virus, we investi gated whether zinc salts (Zn) could potentiate the antiviral action of nati ve human leukocyte interferon (HuIFN-alpha) and rHuIFN-gamma. We found that HuIFN-alpha was potentiated tenfold at rather low levels of IFN activity ( 0.6-0.8 U/ml), resulting in 100% protection. Zn alone gave only marginal pr otection, if any. In contrast to HuIFN-alpha, rHuIFN-gamma directly increas ed the cytopathic effect of rhinovirus at low levels (< U/ml) but protected the cells at higher IFN levels (5-20 U/ml). No potentiation was seen with Zn. HuIFN-<beta> protected against rhinovirus at the same doses as used wit h HuIFN-alpha, but in contrast to HuIFN-alpha, no potentiation was noted.