Morphogenesis of porcine rotavirus in porcine kidney cell cultures and intestinal epithelial cells.

The morphogenesis of porcine rotavirus was similar in vitro in porcine kidney (PK) cell cultures and in vivo in porcine epithelial cells as examined by electron microscopy. Infected cells contained cytoplasmic, non-membrane-bound viroplasm and accumulations of virus particles within cisternae of the rough endoplasmic reticulum (RER). Three types of virus particles were noted: double-shelled or complete particles which averaged 77 nm in diam.; single-shelled or naked particles which ranged from 50 to 55 nm in diam.; and electron-dense nucleoids, or cores, 31 to 38 nm in diam. Virus particles acquired outer shells by budding through either matrices of granular, electron-dense viroplasm or membranes of distended RER. Accumulation of numerous single-shelled particles was observed only in PK cell cultures containing a high percentage of infected cells. In these cells, virus release occurred through disruption of the plasma membrane. Tubules, similar in diameter to the single-shelled particles, were observed in the nuclei of a few infected PK cells.