Inhibition of IL-12 primarily by HHV-6 virions and not by soluble factors. HHV-6A infectious supernatants were ultracentrifuged; both the ultraspin supernatant (sup) and the pellet were tested for their ability to inhibit IL-12 p70 production upon IFN-γ and LPS stimulation (A). TNF-α levels were also tested in parallel (B). Mean results (± SD) from 3 donors are presented.