Preparation of Newcastle disease virus hemagglutination-inhibition test antigen

A method of preparing antigen for Newcastle hemagglutination-inhibition (HI) tests is described; polyethylene glycol precipitation is used for the virus concentration. The virus was inactivated with either formalin or beta-propiolactone. Glycerin was used to stabilize the hemagglutinin activity of the antigen. The stability, uninfectivity, and slow eluting features of the antigen should aid in obtaining accurate HI results without the risks inherent in the use of live virus.