A new landscape of rabbit gut microbiota shaped by the infection of precocious parasites of Eimeria intestinalis

Rabbit intestinal coccidiosis is caused by one or several Eimeria species, which cause intestinal damage and secondary bacterial infection. However, the impact of Eimeria infection on gut microbiota is much unknown. To evaluate the influence, we detected the feces flora of SPF rabbits infected with the 1 x 10(4) oocysts of E. intestinalis wild type (WT) and a precocious line (EIP8), a highly pathogenic species, by 16S rRNA sequencing. The microbiota of newly weaned rabbits post vaccination with low doses of EIP8 oocysts was also detected. In SPF rabbits, while Ruminococcaceae, Lachnospiraceae, and Bacteroidaceae were dominant families in all groups, EIP8 infection induced less changes in beta-diversity. In EIP8-infected rabbits, the intestinal flora whose abundance changed post infection accounted for less than 5.23 % of the entire flora. In comparison, it accounted for 27.18 % in WT group on d14 PI, while it was more than 20 % in diclazuril control group on d7 or d10 PI. The amount of fecal IgA and the abundance of IgA-production-related bacteria were similar in either EIP8 or WT infected rabbits. In the newly weaned rabbits, vaccination with EIP8 provided sufficient protection against challenge with WT parasites, as the body weight gain of vaccinated rabbits was similar to that of untreated animals, as well as more than 80 % reduction of oocyst output was detected when compared with unimmunized and challenged animals. Moreover, the vaccination had no significant impact on rabbit microbiota. Together, our findings suggested that the precocious line of E. intestinalis, compared with WT, induced a new fecal microbiota biodiversity in rabbits.