Enterovirus type 70-neutralizing IgM in animal sera

The neutralizing activity against human enterovirus type 70 was found in serum samples from normal cattle, horses, sheep, goats, swine and chickens raised in Japan. The frequency was variable depending upon animal species and the year of bleeding. The neutralizing activity in bovine sera was shown to reside in IgM by sucrose gradient centrifugation and immune gel electrophoresis. These findings suggested that the neutralizing substance in domestic animal sera is the antibody of IgM class elicited by unidentified viruses antigenically related to human enterovirus type 70.