RNase of classical swine fever virus: biochemical characterization and inhibition by virus-neutralizing monoclonal antibodies.

The structural glycoprotein E0 of classical swine fever virus (CSFV) possesses an intrinsic RNase activity. Here we present the first comprehensive biochemical characterization of E0, using a recombinant glycoprotein expressed in insect cells. We were able to show that the presence of neither carbohydrate moieties nor disulfide bonds is a prerequisite for RNase activity. In addition, virus-neutralizing and nonneutralizing anti-E0 monoclonal antibodies were tested for their ability to influence RNase activity. In these experiments, the antibodies which effectively blocked the infection of STE cells also exerted a high degree of E0 RNase inhibition. This correlation suggests that the RNase activity of CSFV E0 plays a role in the viral life cycle.