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 a T. trichiura infection in a non-primate host using a humanised-microbiota mouse model. We further show, in vitro, that hatching of T. trichiura was triggered by mucosal scrapings of the caecum of human microbiota-associated mice, but not from wild-type mice, which only induced T. muris hatching. Comparative metagenomic analysis of the murine versus humanised microbiomes directly implicated specific bacterial species in T. trichiura egg hatching. Additionally, we demonstrate that host tissue does not directly determine host specificity, as T. trichiura readily 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.