Vaccination of Chickens with a Clone-Selected Lastoa Strain of Newcastle Disease Virus ,

Abstract

A cone-selected Lasota strain of Newcastle disease (ND) was found to be more immunogenic than the B1 strain but less immunogenic than the regular Lasota strain while having the same pathogenic index as the B1 strain. The geometric mean hemagglutination-inhibition (HI) titers induced in chickens vaccinated with the cloned Lasota strain were higher than those induced in chickens vaccinated with the B1 strain but were found to be slightly less than the titers obtained in chickens vaccinated with the regular Lasota strain.The clone-selected Lasota strain had essentially the same spreading potential as the regular Lasota strain, as indicated by geometric mean titers and challenge mortality of nonvaccinated chickens which were placed in contact with the vaccinated chickens. Oral, ocular, or aerosol vaccination of maternally immune chickens with the clone-selected Lasota strain gave essentially the same protection as those vaccinated with the regular Lasota strain.