Figure 2. HCMV infects pDCs nonpermissively. Through engagement of the TLR7 and/or TLR9 pathways, HCMV induces production of IFN-α and secretion of IL-6 and IL-10. HCMV infection in pDCs has an inhibitory effect on T-cell proliferation, but triggers B-cell activation and proliferation and antibody production. HCMV infection of pDCs has a pronounced effect on NK cells: it increases expression of NK-cell activation markers, induces production of high levels of inflammatory cytokines, and increases migration, but impairs the ability to kill target cells. IFN-α production by HCMV-infected pDCs together with chronic HCMV antigen stimulation may lead to differentiation of CD4⁺CD28-null T cells.