Fig. 2

Intestinal IgA of WLMB has a higher bacterial affinity than that of AA. A Number of IGHV gene used in duodenal IgA between AA and WLMB. B Usage frequency of IGHD gene in duodenal IgA. C Frequency of mutations targeting the FR1, CDR1, FR2, CDR2, and FR3 regions of duodenal IgA. D The distribution of different sized CDR3 fragments for IGH amino acid sequences in duodenal IgA. E Flow cytometric analysis of the proportion of IgA-coated bacteria in small intestine, the IgA⁺ gates were determined follows negative control. F Overview of 16S rDNA sequencing of IgA-coated bacteria in the duodenum based on FACS. G Rarefaction curves of observed OTUs. H Venn diagram depicting the number of OTUs identified in total bacterial and IgA-coated bacterial in duodenum. I Alpha diversity indices of IgA-AA and IgA-WLMB. J Cladogram based on LEfSe. Biomarker taxons were heighted by colored circles, circle’s diameter is relative to the abundance of biomarkers. Data are means ± SEM (n = 6); unpaired Student’s t test; * P < 0.05, ** P < 0.01, *** P < 0.001