TNF and gastroenteritis: Severe gastroenteritis is a significant clinical sign of TGEV infection, and it is now well-established that NF-κB is a key regulator of inflammation because of its ability to induce the transcription of pro-inflammatory genes such as tumor necrosis factor α (TNF-α), interleukin (IL) −1β, IL-6, and IL-8 [14,15].