Dynamic stability of the cyathostomin – gut microbiota interactions in horses

Abstract

International audienceThe dynamics of the helminth-microbiota assemblage in their host remain largely unexplored. Here, we used the horse – cyathostomin system to quantify the resilience of the nematode-bacteria interactions following an anthelmintic treatment. Ten infected Welsh ponies received a pyrantel treatment to eliminate adult parasites in the gut lumen. These were matched with uninfected treated individuals to isolate the treatment effect. These two groups were matched with untreated control individuals. Metabarcoding approaches were implemented to track faecal microbiota and cyathostomin community compositions over a 42-day time-course.The nemabiome approach identified 13 species overwhelmed by the abundance of Cylicocyclus nassatus that accounted for 52.6% of the overall diversity. The gut microbiota of infected horses exhibited higher Shannon entropy and bacterial species turnover, suggesting orderly rearrangements of assemblages. Enterococcus abundance could however discriminate between infected and uninfected ponies.Following pyrantel treatment, the dynamic stability of bacterial community in treated horses chiefly increased towards unstability but reached a stasis with limited variation across ponies afterwards. This would be compatible with creation of a new equilibrium between bacterial genera upon pyrantel treatment. Using a convergent cross-mapping approach, we evidenced a set of core bacterial genera, i.e. Fibrobacter, Saccharofermentans, and Aloprevotella that likely provide the stabilizing forces towards this new equilibrium. The cyathostomin community recovered quickly with a primarily unchanged structure 42 days after treatment.Our data provide the first description of the resilience of the horse gut microbiota in infected horses, indicating a heavily canalized system