Light immunofluorescent and electron microscopy of duck virus enteritis (duck plague).

Abstract

The oesophagus, liver, spleen, small intestine, thymus and bursa of Fabricius of 12 ducklings inoculated with a local strain of duck virus enteritis virus were examined by light, immunofluorescent and electron microscopy. Gross and microscopical lesions in those organs examined developed in close association with the appearance and distribution of viral antigens or virions demonstrable by immunofluorescent and electron microscopy. After being assembled in the nucleus, viral nucleocapsids seemingly migrated to the cytoplasm. In the cytoplasmic matrix, they acquired electron-dense material to form tegument and then became enveloped by passing through the membrane investing tubules, vesicles or vacuoles. These cytoplasmic spacing containing mature virions coalesced to form larger inclusions. There were two types of inclusions, light and dark, in the cytoplasm, and they apparently corresponded to eosinophilic cytoplasmic inclusions seen in stained preparations or to larger fluorescing granules. The light cytoplasmic inclusions contained numerous virions and tubules, possibly representing overproduced viral envelopes. In the dark cytoplasmic inclusions, virions and tubules, possibly representing overproduced viral envelopes. In the dark cytoplasmic inclusions, virions and tubules which appeared to be in the process of disintegration were embedded in dense material. This type of inclusions was interpreted as representing later stages of inclusion formation and a form of lysosome.