A Serum Inhibitor in Animal and Human Sera of Bovine Enteroviruses

A serum factor having neutralizing activity against bovine enteroviruses is described. It is significantly inactivated by trypsin, sodium periodate and neuraminidase, stable at 56°C for 30 min, and present in the sera of man and other species. Neutralizing activity is best demonstrated using a minimal viral challenge, at 37°C for a relatively long period of contact. The level of the inhibitor does not vary with age or illness. Part of the activity is associated with serum Fraction V. Although the neutralizing activity is relatively specific against viruses the inhibitor is widely reactive and combines with tissue homogenates and certain bacteria. The relationship of this inhibitor to other inhibitors is discussed.