ULTRASTRUCTURE AND IMMUNOCYTOCHEMISTRY OF BHK-21-CELLS INFECTED WITH A MODIFIED BUCYRUS STRAIN OF EQUINE ARTERITIS VIRUS

Morphogenesis of a modified Bucyrus strain of equine arteritis virus ( EAV) in BHK-21 cells was studied. Bacillary tubules were first detecte d in the cytoplasm 8 h after infection, and mature virions 79 to 122 n m in diameter, 101 nm on average, were mostly observed in the cisterna e of the rough endoplasmic reticulum (RER) at 12 h or later. They had isometrical cores and morphological subunits in the outer layer. Buddi ng occurred from the RER and the outer nuclear membrane, but not from the cell surface. Structural linkage was detected between the tubule a nd the virus core. Aberrant strands were occasionally demonstrated wit hin the nucleus 12 h after infection, and immunofluorescence and immun ogold labeling revealed viral antigen also in the nucleus.