Transmission electron microscopy of HHV-8 virions in TPA-treated BCBL-1 cells at 48 hours of culture.

The following cells are depicted: (A) untreated cells, (B) cells treated with 20 ng/mL TPA at 0 hour, (C) cells treated with TPA plus 5 ng/mL hr-NGF at 0 hour, and (D) cells treated with TPA plus 30 μg/mL anti-NGF Ab at 0 and 24 hours. (A) No HHV-8 viral particles were observed in control cells. (B) Mature enveloped virions originated from the nucleus of a TPA-treated cell. A detail, at higher magnification, is shown in the corner. (C) View of numerous mature HHV-8 virions, approximately 110 nm in diameter, in the nucleus of a cell treated with TPA plus hr-NGF. A detail, at higher magnification, is shown in the corner. (D) Nucleus of an apoptotic cell in a culture treated with TPA plus anti-NGF Ab. The condensed chromatin of the apoptotic cell can be seen along the nuclear membrane. Numerous defective virus particles, with internal electron dense structures possibly representing viral DNA, were observed. A detail of a defective virion can be seen at higher magnification in the corner. The bars in (A, B) equal 1 μm; in (C, D), 0.5 μm; and in the corners, 150 nm.