Electron Microscope Studies of HeLa Cells Infected with Herpes Virus

SUMMARY: Monolayer cultures of HeLa cells were exposed to a high multiplicity of herpes virus per cell. Samples of cells taken at successive time intervals after infection were sectioned and examined by electron microscopy for characteristic ringed particles. Replicate cultures of cells were assayed for infective virus. Despite an estimated input of 6 HeLa plaque-forming units (pfu)/cell, an infective centre count indicated that only 6% of the cells yielded virus. No increase in infective virus was found in the cultures at 9 hr. and no characteristic particles were found in sections of 28 cells. At 12 hr. new virus appeared in the cell fraction and particles were found in the nuclei of 2 of 25 cells. At 26 hr. after infection and later, there was a large increase in virus in both cell fraction and medium, and large numbers of particles were present in the nucleus and cytoplasm and on the cell surface.