Herbal treatment of IBV–E. coli salpingitis establishment of a salpingitis model of layer chickens caused by co-infection of infectious bronchitis virus and Escherichia coli for the curative efficacy assessment of three Chinese herbal compounds

Salpingitis is a common disease affecting production performance of layer chickens, with pathogenic microbial infections being one of the primary etiological factors. Clinically, Infectious bronchitis virus (IBV) and Escherichia coli (E. coli) can often be simultaneously isolated from cases of oviduct inflammation in laying hens. However, the specific roles played by these two pathogens in the occurrence of salpingitis remain unclear. In this study, IBV and E. coli were inoculated in laying hens via single and mixed infections in order to establish an salpingitis model, and its pathogenesis was investigated through transcriptome sequencing analysis. Furthermore, the therapeutic effects of three modified formulas on the salpingitis of layer chickens were assessed. Results demonstrated that the typical salpingitis model can be successfully replicated by co-infection with specific dose of IBV and E. coli, whereas infection with either pathogen alone at the same concentrations failed to induce the disease. Primary infection with IBV significantly enhanced the adhesion and pathogenicity of E. coli. The co-infection of two pathogens activated the TLR4/MyD88/NF-κB signaling pathway, leading to an increase in the expression of proinflammatory cytokines IL-6, IL-1β, and IL-8, which triggers a cytokine storm. Three modified Chinese including modified Sihuang Zhili San, Modified Baitouweng San, and Modified Siwei Chuanxinlian Formula were effective in inhibiting pathogen proliferation, repairing oviduct mucosal damage, suppressing the activation of the TLR4/MyD88/NF-κB pathway, and reducing inflammatory responses in the oviduct of laying hens. Among these three modified formulas, Modified Sihuang Zhili San demonstrates the best therapeutic effect. The results may provide new references for pathogenesis study and treatment of Salpingitis in layer chickens. These findings provide new insights into the pathogenic mechanisms of oviduct inflammation in laying hens and offer a reference for its prevention and control.