A live attenuated turkey rhinotracheitis virus vaccine. 2. The use of the attenuated strain as an experimental vaccine.

An attenuated turkey rhinotracheitis (TRT) vaccine strain, when given either by eye drop or by aerosol, has been shown to be effective in protecting 1- to 11-day-old turkey poults against an experimental challenge with TRTV up to 14 weeks later. TRT antibody-free poults and poults hatched from TRT-immune dams were both equally well protected, although a high proportion of the latter did not respond serologically to the vaccine. As little as 1 CD50 of vaccine was found to be effective in protecting poults against challenge. Immunity developed within about 6 days of vaccination of 7-day-old TRT antibody-free poults and humoral antibody persisted for at least 14 weeks after a single vaccination at 4 weeks of age.