TNF and infection: We further examined the transcription and expression of tnf-α and iNOS, a downstream gene of the IL20R-JAK/STAT3 pathway regulated by STAT3 activation, using HaCaT cells uninfected or infected with RH-WT or RH-Δrop18. The most significant tnf-α and iNOS transcription; and tnf-α translation was observed at 20 min post-infection in both RH-WT and RH-Δrop18 infection groups, but RH-WT resulted in a significantly higher level than RH-Δrop18 (Fig. 5d-f, Additional file 5: Figure S4a).