In primary MTEC, type I and III IFNs are induced upon influenza virus A infection, in a MAVS and replication dependent way.

(A) Mouse tracheal epithelial cells were costained for ZO-1 (green) and β tubulin IV (red), or Mucin 5A (red) and Clara cell secretory protein (CCSP) (green). Images were acquired at ×20 magnification. (B) Total RNA from mock infected and PR8 infected (moi = 0.3) MTEC was analysed using Affymetrix Mouse Genome 430 2.0 microarrays. The signal intensity of each probe was first normalized on the median intensity of that probe across the control group and then represented as log2 fold change relative to the controls. Asterisks indicated statistically significant differences (unpaired t test; **, p<0.01). (C) qRT-PCR analysis of IL-28A/B and IFNβ1 transcripts of MTEC derived from wild-type, TLR7−/−, MyD88−/−, TRIF−/− and MAVS−/− mice, mock infected or infected with either PR8 or heat inactivated PR8. Fold induction is relative to mock treated samples at 24 hpi +/− SEM. (D) IL-28A/B level in the supernatants of the indicated cultures were measured by ELISA 24 hpi.