Morphogenesis of human rotavirus type 2 Wa strain in MA 104 cells

Morphogenesis of human rotavirus type 2 Wa strain in MA 104 cells was observed. The virus antigen in the cytoplasm was detected by indirect immunofluorescence twelve hours after infection. The cytopathic effect occurred 24 hours after infection when virus particles were detected by EM in the culture fluid as well as in thin sections of the infected cells. Virus particles were observed in the dilated RER, nuclear envelope (perinuclear space), viroplasm, and a lysosome-like body. Three types of virus particles were noted: double-shelled particles 75-85 nm in diameter, single-shelled particles 64-68 nm in diameter and electron-dense nucleoids or cores 32-40 nm in diameter. The outer shell of virus particles was acquired by budding through the membrane of the dilated RER. Tubular structures, similar in diameter to the single-shelled particles, were found in the cytoplasm and nucleus of infected MA 104 cells. Bundles of filaments or the leaflet-like inclusion bodies of membrane-bounded bundles of filaments were found in the cytoplasm and seemed to be associated with virus particles.