Relationship Between Histomonas meleagridis Infection and Cecal Intestinal Microbiota of Chickens

Histomonosis, caused by <i>Histomonas meleagridis</i>, leads to economic losses in the poultry and livestock industry. In recent years, studies on the role of intestinal microbiota in host physiological health have attracted growing attention. Understanding the changes in gut bacterial communities of chickens is crucial for improving poultry and livestock production. This study investigated the impact of <i>Histomonas meleagridis</i> infection on the growth performance, overall health, and cecal microbiota composition of chickens. Body weight changes and pathological alterations were assessed at different time points post-infection through animal experiments, with 7 days post-infection defined as the early stage and 14 days as the peak stage of infection. Cecal content samples were collected from the 7-day control group (G1), 7-day infected group (G2), 14-day control group (G3), and 14-day infected group (G4) for 16S rRNA sequencing analysis. The microbial diversity analysis revealed that <i>H. meleagridis</i> infection altered the number of microbial species in the cecal microbiota of chickens. The alpha diversity index was significantly reduced (<i>p</i> < 0.05), and principal coordinate analysis (PCoA) revealed significant structural differences between infected and control groups (<i>p</i> = 0.001). Taxonomic composition analysis showed that beneficial gut bacteria, such as Firmicutes and <i>Lactobacillus</i> spp., decreased in abundance, whereas Bacteroidota, Proteobacteria, <i>Escherichia</i> spp., and <i>Fusobacterium mortiferum</i> were enriched in the infected group. LEfSe analysis indicated that G1 was enriched with <i>Oscillospiraceae</i> and <i>Blautia</i>; G2 with <i>Christensenellaceae</i>; G3 with <i>Verrucomicrobia</i> and <i>Lactobacillus aviarius</i>; and G4 with Proteobacteria and Fusobacteria. In conclusion, <i>H. meleagridis</i> infection markedly altered the cecal microbiota composition by shifting the relative abundances of beneficial and pathogenic bacteria, resulting in reduced microbial diversity.