Adult duck fecal microbiota transplantation alleviates short beak and dwarfism syndrome in ducklings by inhibiting Th17 cell differentiation

Background: The novel goose parvovirus (NGPV) infection in Cherry Valley ducks induces short beak and dwarfism syndrome (SBDS) in ducklings, resulting in significant economic losses for the duck production. Our previous study demonstrated that the intestinal microbiota is involved in the disease progression of SBDS. Since NGPV predominantly infects young ducklings and rarely affects adult ducks, whether reshaping the intestinal flora of ducklings through fecal microbiota transplantation (FMT) from adult ducks could alleviate SBDS symptoms in ducklings is an interesting question.Results: The results of NGPV infection in ducklings and adult ducks demonstrated that ducklings were more susceptible to NGPV compared to adult ducks, and the abundance and diversity of fecal microbiota were significantly higher in adult ducks than in ducklings. The fecal microbiota transplantation from adult ducks (FMT-A) was used to establish a duck model of intestinal flora remodeling. The results showed that FMT-A treatment could alleviate the reduction of body weight, beak length, beak width, tibia length, breast and leg muscle weight in ducklings caused by NGPV infection, and the improvement of the area of single muscle cells was observed by HE staining. Furthermore, FMT-A alleviated dysbiosis of the gut microbiota and intestinal tissue damage in infected ducks, while enhancing glycogen content in the intestinal mucosa and upregulating the expression of the tight junction protein ZO-1. This study also noted that FMT-A treatment increased tibia length, expanded the epiphyseal region, and reduced osteoclast numbers in ducklings. Moreover, FMT-A suppressed the expression of the Th17 cell-specific transcription factor retinoic acid receptor-related orphan receptor γt in the ileum and bone, and decreased the expression levels of pro-inflammatory cytokines IL-17A, IL-22, and TNF-α in the ileum, bone, and serum. Conclusions: These findings indicate that ducklings are more susceptible to NGPV than adult ducks. The diversity and abundance of fecal microorganisms in adult ducks are significantly higher than those in ducklings. The FMT-A can help maintain the stability of the intestinal flora, mitigate intestinal barrier damage, inhibit Th17 cell differentiation, thereby reducing abnormal bone development, and ultimately alleviate SBDS in ducklings.