Virus replication and localization of varicella-zoster virus antigens in human embryonic fibroblast cells infected with cell-free virus.

When human embryonic fibroblast cells were infected with cell-free varicella-zoster virus, virus replication began between 8 and 14 h postinfection, and 4 more h werp required for the virus to infect neighboring cells. Virus-specific antigens were traced by the anticomplement immunofluorescent antibody technique. Virus antigen was first detectable 2 h postinfection in the cytoplasma, and diffuse fluorescence was observed in the nucleus as early as 4 h after infection. The nuclear fluorescence got brighter and cytoplasmic fluorescence was observed at 14 h postinfection. The spread of virus to the neighboring cells was recognized in 18 h postinfection. In the period of 24 to 48 h, antigens were seen at the nuclear membrane region and in the cytoplasma. Very strong fluorescence was restricted mainly to the nucleus, when phosphonoacetic acid or cytosine arabinoside was added to the infected cultures and the cells were incubated for 48 h.