A pig model of the human gastrointestinal tract

Easy access to next generation sequencing has enabled the rapid analysis of complex microbial populations. To take full advantage of these technologies, animal models enabling the manipulation of human microbiomes and the study of the impact of such perturbations on the host are needed. To this aim we are developing experimentally tractable and clinically relevant pig models of the human adult and infant gastro-intestinal tract. The intestine of germ-free piglets was populated with human adult or infant fecal microbial populations, and the piglets were maintained on solid or milk diet, respectively. Amplicons of 16S rRNA V6 region were deep-sequenced to monitor to what extent the transplanted human microbiomes changed in the pig. Within 24 h of transfer of human fecal microbiome to pigs, bacterial microbiomes rich in Proteobacteria emerged. These populations evolved toward a more diverse composition rich in Bacteroidetes and Firmicutes. In the experiment where infant microbiome was used, the phylogenetic composition of the transplanted bacterial population converged toward that of the human inoculum. A majority of sequences belonged to a relatively small number of operational taxonomic units, whereas at the other end of the abundance spectrum, a large number of rare and transient OTUs were detected. Analysis of fecal and colonic microbiomes originating from the same animal indicate that feces closely replicate the colonic microbiome. We conclude that the pig intestine can be colonized with human fecal microbiomes to generate a realistic model of the human GI tract.