CHARACTERIZATION OF BOVINE VIRAL DIARRHEA VIRUSES .4. SEQUENTIAL DEVELOPMENT OF BVD VIRAL ANTIGEN IN CELL CULTURES STUDIED BY IMMUNOFLUORESCENCE

Embryonic bovine kidney cell cultures infected with the NADL strain of bovine viral diarrhea (BVD) virus, and PK-15 cells infected with an adapted strain of BVD virus were stained with fluorescein-isothiocyanate-conjugated anti-BVD serum globulins at sequential time periods. The development of virus-induced fluorescing antigens within infected cells was then studied. From this time-study, it appears that BVD virus-induced fluorescing antigens originate in the nucleus of the host cell, and are seen next in a paranuclear position (probably in the Golgi Apparatus); the antigen later appears diffusely throughout the cytoplasm of the cell, forms granular cytoplasmic bodies, then fades and eventually disappears unless the host cell is destroyed by the virus. The time-sequential development of fluorescing antigen in BVD virus-infected cells correlates approximately with the appearance of soluble antigen. The disappearance of fluorescence from the cytoplasm corresponds approximately with the synthesis of mature infective viral particles in the virus-cell system. © 1969 Springer-Verlag.