Alteration in the Gut Microbiota of Chickens Resistant to Eimeria tenella Infection

Avian coccidiosis, caused by several species of <i>Eimeria</i>, is a widespread and economically important poultry disease that inflicts severe losses in the poultry industry. Understanding the interplay between <i>Eimeria</i> and gut microbiota is critical for controlling coccidiosis and developing innovative treatments to ensure good poultry health. In the present study, chickens were immunized six times with a low dose of <i>Eimeria tenella</i>, resulting in complete immunity against <i>Eimeria</i> infection. The results of fecal microbiota transplantation showed that the gut microbiota of immunized chickens induced a certain degree of resistance to coccidial infection. To investigate the types of intestinal microbiota involved in the development of resistance to <i>Eimeria</i>, the intestinal contents and fecal samples from both immunized and unimmunized groups were collected for 16S rRNA gene sequencing. The results showed that, at the genus level, the abundance of the <i>Eubacterium coprostanoligenes</i> group, <i>Erysipelatoclostridium</i>, <i>Shuttleworthia</i>, and <i>Colidextribacter</i> was significantly increased in the intestinal content of immunized chickens, whereas the abundance of <i>Eisenbergiella</i> was significantly decreased. In fecal samples, the abundance of Clostridiaceae and Muribaculaceae significantly increased, whereas that of Bacillales significantly decreased. These findings will help to elucidate the interactions between <i>E. tenella</i> and the gut microbiota of chickens, providing a basis for isolating <i>E. tenella</i>-resistant strains from the gut microbiome and developing new vaccines against coccidiosis.