Host, parasite, and microbiome interaction: Trichuris ovis and its effect on sheep gut microbiota

Sheep that are infected with gastrointestinal helminths experience a significant impact on their health and productivity. Among the helminths, nematodes like Haemonchus contortus, Oesophagostomum spp., Bunostomum trigonocephalum, Nematodirus battus, Trichostrongylus spp. and Teladorsagia circumcincta are particularly pathogenic. Understanding the interactions among parasites, hosts, and their microbiomes is crucial in developing new approaches in the management of parasites. This study examines the bacterial profile of Trichuris ovis, a highly prevalent nematode among Kashmir Merino sheep, and the influence of nematode infection on the caecal microbiome of its host. Sheep were selected based on T. ovis infection status, and samples were collected from infected and non-infected caecum. The 16S rRNA metagenomic analysis revealed distinct microbial communities in T. ovis, infected caecum, and non-infected caecum. Proteobacteria dominated the T. ovis microbiome, while infected caecum was rich in Bacteroidota and Spirochaetota, and non-infected caecum had a higher proportion of Firmicutes and Verrucomicrobiota. At the genus level, T. ovis was predominantly associated with Escherichia/Shigella, while infected caecum had higher proportions of Bacteroides, Prevotella, and Treponema. Non-infected caecum was characterized by WCHB1-41, Prevotella, and Succiniclasticum like genera. Alpha and beta diversity indicated significant differences in microbiome among the groups, with higher diversity observed in infected caecum. The study found T. ovis infection significantly alters the caecal microbiome of sheep, introducing potentially pathogenic bacteria and reducing beneficial ones. These findings underscore the complex relationship between host, parasite, and microbiome, highlighting the need for comprehensive strategies to manage helminth infections and their broader ecological impacts.