Abstract
Summary
The pathogenicity of the 82nd subculture of the hamster-adapted California strain of Newcastle virus used as an immunizing agent was negligible in this experiment.
Through injection of the living hamster-adapted California strain No. 11,914, of Newcastle virus, young chickens were successfully immunized against the egg-adapted California, Colorado, and Connecticut strains. The modified Newcastle virus also produced exceptionally good protection in chickens to contact with chickens infected with all above-mentioned strains.
Susceptible birds, used as contact controls with birds injected with modified hamster-adapted Newcastle virus, failed to show clinical evidence of spread of this modified strain. There appeared to be some resistance to challenge injection in those birds challenged with the Connecticut strain, as compared with the normal unvaccinated control chickens of this group.
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