Chronic Trichuris muris Infection Decreases Diversity of the Intestinal Microbiota and Concomitantly Increases the Abundance of Lactobacilli

The intestinal microbiota plays critical roles in both health and disease. It has become increasingly clear that pathogen exposure can affect the composition of microbial communities in ways that are poorly understood. We set out to investigate the effect of parasite infection on the murine intestinal microbiota, utilizing the large-intestinal dwelling whipworm Trichuris muris. Our data demonstrate that chronic infection with T. muris results in a profound shift in bacterial communities after 3-4 weeks of infection, with a drop in overall bacterial diversity, and increase in the relative abundance of the bacterial family Lactobacillaceae. In parallel, the immune system was highly affected by the infection, with a marked reduction in the ratio of regulatory to inflammatory immune cells. These changes however appeared independent of the change in the microbiota. These findings shed light on the important role of worm infections on the gut microenvironment, especially with regard to ongoing trials of worm treatment against immune-associated diseases.