Fig. 3

Induction of anti-E. coli SIgA by expression of apyrase. a Statistical analysis by flow cytometry of Tfh cells and Annexin V⁺ cells within Tfh cells from PPs of mice immunized with E.coli^pBAD28 or E.coli^pApyr at day 22. b Flow cytometry for anti-E. coli IgA in intestinal wash from mice immunized with E. coli^pBAD28 or E. coli^pApyr. c Intestinal anti-E.coli IgA titer in non-immunized mice (CTRL) and mice immunized with E. coli^pBAD28 or E. coli^pApyr. d Diagram showing the immunization protocol with E.coli^pBAD28 and E.coli^pApyr in mice maintained with Chloramphenicol and Ampicillin (CA) (a bactericidal mix active on endogenous flora but not on CA-resistant E. coli^pBAD28 and E. coli^pApyr) or Penicillin/Streptomycin/Vancomycin (PSV) (bactericidal on both endogenous flora as well as E. coli transformants) in drinking water. e Fold increase of ileal ATP in mice maintained in PSV or CA before (day 8) and 12 h after (day 9 + 12 h) orogastric gavage with the indicated transformants. f Intestinal anti-E.coli IgA titer in untreated mice (CTRL) or in response to E. coli^pBAD28 (left panel) or E. coli^pApyr (right panel) gavaging in mice maintained in PSV or CA. The boxplots in a and e show median and upper and lower quartiles. The extreme lines show the highest and lowest value . The boxplot is overlaid with the visualization of single observations. Two-tailed Mann–Whitney U-tests. **p < 0.01 a and Kruskal–Wallis with Dunn’s post-test. *p < 0.05, **p < 0.01 c, e, f. One representative experiment out of at least two is shown