Differences in the susceptibility of human blood cell lines to vaccinia virus

The replication of vaccinia virus in human hematopoietic cell lines was studied, to ascertain whether the cell type and the stage of diifferentiation can influence the outcome of the infection. Lymphocytic NB104 cells and myelogenous leukemic K562 cells can be productively infected with vaccinia. Whereas NB104 cells were readily lysed, cells from the K562 line stayed persistently infected. Infection of promyelocytic leukemia HL₆₀ cells results in an abortive infection in which the virus is uncoated, does not replicate, remains latent and can be rescued by cocultivation with permissive cells. Upon addition of phorbol esters to HL₆₀ cell cultures, virus replication resumed. These results suggests that, although vaccinia virus replication is almost independent of host-specific functions, the outcome of the infection may depend on the cell type and its stage of differentiation.