# Relationship Between Histomonas meleagridis Infection and Cecal Intestinal Microbiota of Chickens

## TL;DR

This study shows how infection with Histomonas meleagridis affects chicken growth, causes lesions, and changes gut bacteria in the cecum.

## Contribution

The study identifies specific shifts in cecal microbiota composition during H. meleagridis infection in chickens.

## Key findings

- Infected chickens had reduced body weight and severe liver and cecum lesions at 14 days post-infection.
- Beneficial bacteria like Verrucomicrobia and Lactobacillus aviarius decreased, while harmful bacteria like Proteobacteria and Fusobacteria increased.
- Microbial diversity and structural differences were significantly altered in infected chickens compared to controls.

## Abstract

This study evaluated the effects of Histomonas meleagridis infection on growth performance, lesion indicators, and the composition of the cecal microbial community in chickens. The results showed that fourteen days post-infection represented the peak stage of disease development. Compared with the control group, infected chickens exhibited a significant reduction in body weight, along with severe lesions in the liver and cecum. At the same time, the abundance of beneficial bacteria in the cecum, such as Verrucomicrobia and Lactobacillus aviarius, decreased, whereas the abundance of harmful bacteria, including Proteobacteria and Fusobacteria, increased. These findings contribute to a better understanding of microbial changes in the chicken cecum following infection with H. meleagridis.

Histomonosis, caused by Histomonas meleagridis, 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 Histomonas meleagridis 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 H. meleagridis infection altered the number of microbial species in the cecal microbiota of chickens. The alpha diversity index was significantly reduced (p < 0.05), and principal coordinate analysis (PCoA) revealed significant structural differences between infected and control groups (p = 0.001). Taxonomic composition analysis showed that beneficial gut bacteria, such as Firmicutes and Lactobacillus spp., decreased in abundance, whereas Bacteroidota, Proteobacteria, Escherichia spp., and Fusobacterium mortiferum were enriched in the infected group. LEfSe analysis indicated that G1 was enriched with Oscillospiraceae and Blautia; G2 with Christensenellaceae; G3 with Verrucomicrobia and Lactobacillus aviarius; and G4 with Proteobacteria and Fusobacteria. In conclusion, H. meleagridis infection markedly altered the cecal microbiota composition by shifting the relative abundances of beneficial and pathogenic bacteria, resulting in reduced microbial diversity.