Fig 4. Evaluation of CF surface expression following growth in optimized culture media SP1.

CF surface expression was evaluated by MHRA in ETEC strains following overnight growth in M9, SP1, or CFA media in the absence or presence of 0.15% bile salts (BS). CF surface expression was evaluated in strains expressing fimbriae within the CF5a family (A) or other CFs (B). Data are expressed as the minimal hemagglutination titer (MHT) required for agglutination of human or bovine erythrocytes transformed in log₂ for normal distribution. ND indicates not detected. The hemagglutination pattern of CS17-expressing strain is shown in (C). *Strains expressing CS14 or CS17 were cultivated in M9 or CFA media supplemented with BS, while all other strains were cultivated in M9 or CFA in the absence of BS. Data are shown as average of at least three independent replicates, with bars representing the SEM. Statistical analyses were performed using the Mann Whitney test (A), with surface expression in SP1 and CFA media compared to basal M9 media. *p<0.01, ** p<0.001.