lmmunoelectron Microscopic Studies on Infected Cells with Herpes Simplex Virus Type 1

- Using the Horseradish Peroxidase Labeled Fab′ -

Abstract

The immunoelectron microscopic (IEM) studies of HSV-1 infected Vero cells were conducted for the purpose of analysing the fine localization of virus related proteins and their intracellular transportation. For this purpose, horseradish peroxidase (HRP) labeled anti-HSV-1-Fab′(Rabbit, HRP-Fab′) and anti-HSV-1-IgG (Rabbit, HRP-IgG) were prepared. The results were compared histochemically between two labeled antibodies, and the following results were obtained.
1. It was shown that the HRP-Fab′ penetrated deeper into the cell than IIRP-IgG. The former penetrated not only into the cytoplasm but also into the nucleus. By using HRP-Fab′, the HRP reaction products were so sharp that clear distribution of the HSV-1 antigens were obtained.
2. Immediately after the virus adsorption, membranes of cytoplasm and vesicles obtained virus specific antigens. Concerning the virus invasion, two systems have been shown. One was viropexis by phagocytosis and the other was virus-cell membrane fusion.
3. Increased intranuclear staining seen from 2 hr post-adsorptio n suggested the accumulation of the virus related protains in the nucleus.
4. Intranuclear fine granular deposits occupied the wide area of the nucleus. I consider this structure is the same that of the intranuclear inclusion body observed in the specimens under the light microscope.
5. These fine granular deposits increased their density. But two groups of cells were distinguished according to the grade of increased fine granular deposits. In the first group of cells, deposits were increased and in the other, further increase was not observed during the virus replication course. Virus particles appeared in the nucleus in the latter group of cells after 6 hr post-adsorption.
6. Virus particles matured using innernuclear membrane or membrane structure of cytoplasm, and were transported into intracytoplasmic vacuoles or into extracellular space.
7. The advantages of HRP-Fab′ usage in IEM were discussed.