Neutralizing activity in the gastrointestinal contents of piglets vaccinated with an ethylenimine-inactivated porcine enterovirus.

The T80 strain of porcine enterovirus was rapidly and completely inactiviated by ethylenimine in a reaction which appeared to follow first order kinetics. The virus was effectively concentrated 35- to 88-fold, with recovery rates of 23 t0 53%, by adsorption to the polyelectrolyte PE60. Multiple doses of adjuvanted, PE60-concentrated, ethylenimine-inactivated T80 virus given by both the oral and subcutaneous routes induced the appearance of significant levels of virus neutralizing activity in the gastrointestinal tract of piglets vaccinated at four weeks of age. This activity, found predominantly in large intestine, was present 14 days after administration of the first dose of vaccine and significant levels of activity were still detectable six weeks later. Titres of serum virus neutralizing activity were higher and more persistent than in piglets which received live or formaldehyde-inactivated T80 virus by the oral or intramuscular routes.