| 摘 要： | Electron microscopic and autoradiographic studies have revealed that the assembly andmaturation of duck piague virus (DPV, an intranuclear DNA virus) occur both in the nucleusand is the cytoplasm. A dense cytoplasmic matrix (tentatively called viroplast) is the basicorganelle in which the assembly of nucleocapsids occurs. At the early stage of virion matura-tion, dense particles, approximately 40 nm in size, appear and become assembled nucleocapsidstructures later on. As capsids become mature, they obtain a diameter of 95--105 nm. Theviroplast matrix gradually decreases in size, and a loose structure appears inside as thenucleocapsids increase in number. When viroplast has almost disappeared, nucleocapsidsbecome abundant, regularly arranged around the cytoplasmic vacuoles. They bud into thesevacuoles, thereby acquiring their envelopes. These nucleocapsids differ from those found inthe nucleus both in morphology and in distribution. Electron microscopic autoradiography has shown that there is a huge amount of DNA inviroplast. DNA for the assembly of the nucleocapsids in the cytoplasm is derived from thevery viroplast.
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