IL2 and infection: AdCMVΔ24 infection was demonstrated to decrease I.T TReg levels.66 Infection-induced TReg loss has also been shown for VV, with transient reduction identified consequent to pathogen-induced expansion of effector T cells, which decreases availability of IL-2 critical for maintenance of TReg activity.67 More recently, Depaux et al reported that oncolytic VV can directly infect tumor infiltrating TReg cells in murine models of head and neck cancer, resulting in depletion and successful antitumor effects after treatment.68 To improve therapeutic effect, combination agents are being examined.