Abstract
Five groups of 4 wk old turkey poults were each infected by aerosol with a different lentogenic strain of Newcastle disease virus. Four days postinfection, sections of tracheas were collected for histopathologic characterization and virus titration. The most prominent lesions were fibrinopurulent exudate in traceal lumens, hyperplasia of epithelial cells and infiltration by lymphocytes. All strains multiplied to high titers and produced similar microscopic lesions; the number of poults with severe microscopic lesions varied among groups.