Persistent replication of herpes simplex virus type 1 in JOK-1 cells.

Infection of the human B cell line JOK-1 with herpes simplex virus type 1 persisted over a period of more than 12 months (to date). Although limited cytopathic effects were seen, viral infection did not lead to extinction of the culture. Infectious centre assays, performed at various times after infection, revealed that only a small proportion of cells (1 to 10%) produced infectious virus particles. However, immunofluorescence studies showed that at any given time considerably more cells than calculated by infectious centre assays contained the immediate early viral protein ICP4 and expressed viral glycoproteins. These observations were confirmed by in situ hybridization analyses which revealed the presence of viral DNA even in cells not producing infectious particles. Since no evidence for the involvement of interferon could be found, some other so far unknown intrinsic property of the cells must be responsible for the restriction of virus replication and/or maturation.