HISTOCHEMICAL STUDIES ON NEWCASTLE DISEASE VIRUS(NDV) BY FLUORESCENT ANTIBODY TECHNIQUE

I. THE VIRUS ANTIGEN FORMATION IN CULTURED HUMAN CELLS

Abstract

The successful demonstration of NDV multiplication in cultured human cells by hemagglutination and fluorescent antibody technique was presented. The immunohistochemical findings of the virus antigen correlated fairly with the growth curve of hemagglutinating virus, determined from companion cultures. The first appearance of the virus antigen was limited to the perinuclear region of the cytoplasm. There were two different processes of the virus antigen formation in the late stage. In 12 hours, the first accumulation of NDV antigen in detectable amounts was found in the form of a few small particles in the perinuclear region of the cytoplasm. The number and density of the antigen particles increased. They fused to each other, some of them occurred in the other parts of the cytoplasm. In most cells the next outstanding localization of the antigen was found in the surface region of the cytoplasm. It occurred in the form of a band and was getting denser and thicker. The virus seemed to be released into the medium from the surface of the cell, judging from the growth curve of virus. In this case cytolysis did not occur. In some of the cells, however, another process of the virus antigen formation took place in the later period. At 48 to 72 hours, large and dense granules of the virus antigen appeared in the cytoplasm. Their number and size were getting larger and the virus antigen filled the most part of the cytoplasm. Finally it caused the lysis of cells and the synthesized virus was released into the medium. The virus antigen, observed by the method employed, appeared to be limited to the cytoplasm of the cell and never occurred in the nucleus. Binuclear or multinuclear cells were observed in virus-containing cells. It indicated that mitosis or division occurred in virusmultiplying cells.