PVSRIPO has been shown to infect human THP1 macrophages, but unlike many of the cancer cells studied, PVSRIPO infection of macrophages is sublethal and serves to induce expression of major histocompatibility complex class II and costimulatory molecules and further leads to (interferon-β) IFN-β, (interleukin-12) IL-12 and (tumor necrosis factor- α)TNF-α production [90]. Here, TNF is linked to infection.