Infection of human T lymphocytes with varicella-zoster virus: An analysis with viral mutants and clinical isolates

Varicella-zoster virus (VZV) disseminates in the body in peripheral blood m ononuclear cells during chickenpox, Up to 1 in 10,000 mononuclear cells are infected during the viremic phase of the disease. We developed an in vitro system to infect human mononuclear cells with VZV by using umbilical cord blood, In this system, 3 to 4% of T cells were infected with VZV. VZV mutan ts unable to express certain genes, such as open reading frame 47 (ORF47) o r ORF66, were impaired for growth in T cells, while other mutants showed li ttle difference from parental virus. VZV unable to express ORF47 was even m ore impaired for spread from umbilical cord blood cells to melanoma cells i n vitro. Early-passage clinical isolates of VZV infected T cells at a simil ar rate to the Oka vaccine strain; however, the clinical isolates were more efficient in spreading from infected T cells to melanoma cells, This in vi tro system for infecting human T cells with VZV should be useful for identi fying cellular and viral proteins that are important far virus replication in T cells and for the spread of virus from T cells to other cells.