Concentration of inactivated swine influenza virus by molecular filtration for use as a vaccine in gilts before and after breeding.

Inactivated swine influenza virus was concentrated by molecular filtration for use as a vaccine in gilts before and after breeding. The best serologic response followed the use of two 5 ml doses three weeks apart before breeding. Vaccination with two 5 ml doses two weeks apart after breeding did not result in as marked serologic response. All vaccinated gilts produced detectable hemagglutination inhibition (HI) antibody.