Figure 1

IL4I1 protein expression in the chicken cecum afterS. Enteritidis infection determined by triple quadrupole mass spectrometry analysis of proteins from the ceca of control 5-day-old chickens and age-matched experimental chickens 4 days post-infection withS. Enteritidis. A IL4I1 and GAPDH protein quantity expressed as mean peak area of a specific peptide ± SD. Significantly higher peak area was recorded only for IL4I1 and not for housekeeping GAPDH protein. Asterisks—statistically significant difference from non-infected chickens (Mann–Whitney U test, P ≤ 0.05). B Targeted quantification of IL4I1 protein. SRM chromatogram for three transitions of one of IL4I1 peptide from representative cecal sample of non-infected (left panel) or infected (right panel) chicken. Light gray, chromatogram of synthetic peptide standard; dark gray, chromatogram of peptide from cecal samples. The bar charts in top-right corners present comparison of SRM transition intensity ratios. In the case of positive identification, relative intensities should be identical for synthetic heavy and native light peptide, as can be seen in the right panel but not left panel since IL4I1 was not detected in the ceca of control, non-infected chickens.