T lymphocytes activated by interleukin 2 alone acquire permissiveness for replication of herpes simplex virus

Not only mitogen stimulation or mitogen stimulation in combination with interleukin 2 (IL2) was capable of causing susceptibility of human T lymphocytes to herpes simplex virus (HSV) infection, but also selective stimulation with recombinant Il2-induced permissiveness of T lymphocytes to HSV infection. Replication of HSV in such IL2-stimulated T cell cultures was shown to be restricted to a T cell subset not exceeding 5% of the total population. Furthermore, IL2 stimulation was sufficient to obtain virus replication in T cells previously infected by HSV and cultivated for several days. This could not be achieved by stimulation with mitogens such as phytohemagglutinin. The level at which virus replication was restricted in nonpermissive T cells was determined to be before immediate early gene expression as assessed by indirect immunofluorescence with monoclonal antibodies against viral proteins expressed at different stages of the viral replicative cycle.