Clinical material from avian species was examined directly by electron microscopy for the presence of viruses. Mycoplasma-like and coronavirus-like particles were found in chicken feces. These particles did not appear to be associated with disease and were not propagated in the laboratory. Infectious bursal disease virus was readily detected in impression smears of bursas from experimentally infected birds. Poxviruses were demonstrated in smears made from canarypox lesions. Difficulty in distinguishing intact particles of Newcastle disease virus from mycoplasmas and orthomyxoviruses was resolved by treating viral preparations with deoxycholate. After treatment, Newcastle disease virus was lysed, rendering the nucleocapsid visible, whereas influenza virus was mainly unaffected. Viral particles that were recognized only with difficulty by direct elecron microscopic examination were more easily identified using immunoelectron microscopy.
Diagnosis of avian viral diseass by electron microscopy.