ETEC infection induced mRNA expression profile in intestinal tissues. The F4+ ETEC infection was performed on day 0 (D0) and day 1 (D1). Intestinal samples were collected on D4. The mRNA expression in intestinal tissues of F4+ ETEC infected or control pigs was analyzed by qPCR. The mRNA expression was normalized to the reference genes and then to the control group for all separate intestinal tissues. Data are presented as the mean ± SEM (n = 3 per group). JJ: jejunum without Peyer’s patches, JP: jejunum with Peyer’s patches, IL: ileum without Peyer’s patches, IP: ileum with Peyer’s patches, MLN: mesenteric lymph nodes. * indicates significant differences as compared to the control group, * p < 0.05, ** p < 0.01, *** p < 0.001.