Inhibitory effects of recombinant human cystatin C on human coronaviruses

Abstract

Cystatin C, a potent inhibitor of cysteine proteases such as papain and cathepsin B, was examined for its effect on human coronaviruses OC43 and 229e. Both viruses were greater than 99% inhibited by 0.1 mM inhibitor. Endpoint titrations showed that inhibiting activity paralleled that of leupeptin, a serine and cysteine protease inhibitor, and indicated that 1 to 2 microM inhibitor, slightly above physiologic levels, was effective.