Critical Roles of ABC Transporter Protein YheS in Riemerella anatipestifer Caused Infection in Geese

Riemerella anatipestifer (RA) primarily causes infectious serositis in poultry, leading to high mortality.ATP-binding cassette (ABC) transporters are widely distributed on the cell membranes and participate in various biological functions. To study the function of its ABC transporter YheS, we constructed a yheS deletion mutant from goose-derived strain CL-1 and analyzed the effects of YheS deletion on the biological characteristics and pathogenicity of RA. The results showed that yheS deficiency dramatically impaired the growth of RA in Tryptic Soy Broth (TSB). Furthermore, growth analysis after adding DIP and different metal ions into medium determined that YheS is involved in the transport of Fe2+. Stress tolerance test results showed that yheS gene deletion reduced the survival rate of RA under acidic stress. Additionally, we observed that yheS deletion resulted in a more elongated morphology of RA bacterial cells. Transcriptomic analysis showed that, a total of 427 differentially expressed genes (DEGs) were induced by yheS deletion, with 180 genes upregulated and 247 genes downregulated. The data of geese infection test showed that yheS gene deletion led to a significantly reduced virulence of RA, with LD50 increased by at least 1000-fold, significantly reduced bacterial load and diminished pathological damage in the liver, spleen, and brain tissues. Notably, a single intramuscular injection of the ΔyheS mutant at doses above 104 CFU protected goslings against challenge with the wild-type strain RACL-1 at 14 days post-immunization. These findings demonstrate that YheS is a crucial virulence associated factor, and RACL-1ΔyheS represents an ideal candidate.