The ultrastructure of feline infectious peritonitis virus in feline embryonic lung cells

The ultrastructure of feline infectious peritonitis virus in cultured feline embryonic lung cells is reported. Feline embryonic lung cells were infected with feline infectious peritonitis virus and studied by transmission electron microscopy. The virus was not apparent in the cultured cells until 24 h after infection when it occurred in the endoplasmic reticulum, perinuclear space, Golgi apparatus, free in the cytoplasm, in large vacuoles in the cytoplasm and outside the cell membrane. The virus possessed typical coronavirus morphology and was produced by budding into the endoplasmic reticulum. There was no evidence to indicate that this virus budded through the cell membrane. Multinucleate giant cells were formed by infection of the cultured cells with the virus. The host cells were destroyed by the virus and phagocytosed by apparently healthy cells.