Host microbiome determines host specificity of the human whipworm,Trichuris trichiura

Long-term whipworm-host co-evolution has resulted in tropism for the caecum of specific hosts, an organ with the densest microbial population in the body. Here, we demonstrate that the host specificity of human whipworms(Trichuris trichiura)is host microbiome-driven. We successfully establish aT. trichiurainfection in a non-primate host using a humanised-microbiota mouse model. We further show,in vitro, that hatching ofT. trichiurawas triggered by mucosal scrapings of the caecum of human microbiota-associated mice, but not from wild-type mice, which only inducedT. murishatching. Comparative metagenomic analysis of the murine versus humanised microbiomes directly implicated specific bacterial species inT. trichiuraegg hatching. Additionally, we demonstrate that host tissue does not directly determine host specificity, asT. trichiurareadily infected mouse caecaloids. Our findings indicate that host-microbiome-whipworm co-evolution has resulted in exquisite bacterial-whipworm egg interactions critical for hatching and development of these parasites in their definitive hosts.