When virus was dosed per os with virulent Newcastle disease virus and daily
examinations were made of virus in their pooled faeces, virus was recovered on
the 12th day.
No H.I antibodies were produced. The challenge caused two pigeons to
sicken on the 5th day, one of which died on the 8th day while two appeared
unaffected. Two controls died and previous experience was that pigeons are
highly susceptible to the virulent strain. Surviving pigeons had high H.I titres.
It is concluded that the pigeons dosed per os with the virulent virus developed
an increased resistance to the challenge.
A method of live virus immunization in the pigeon is mentioned.