Probiotics have been defined as live microorganisms that are administered in an appropriate amount to provide health benefits to the host animal. In this study, we investigated the effect of L. salivarius DJ‐sa‐01 secreting the 3D8 single‐chain variable fragment (3D8 scFv) on the growth performance, cytokine secretion, and intestinal microbial flora of chickens. The experiment was divided into the control group and L. salivarius expressing 3D8 scFv experimental group. Chicken was fed 10⁹ colony‐forming units (CFUs) of wild‐type (WT) L. salivarius or 3D8 scFv‐secreting L. salivarius daily for 35 days. The administration of L. salivarius expressing 3D8 scFv significantly improved the body weight of chickens compared with the administration of WT L. salivarius . A 16S ribosomal RNA metagenomic analysis showed that Firmicutes , Proteobacteria, Actinobacteria, and Bacteroidetes were the dominant phyla in both experimental groups. At the genus level, Lactobacillus was more abundant (22.82%) in the L. salivarius/ 3D8 group compared with the WT L. salivarius group. The serum levels of cytokines, such as IL‐8, TNF‐α, IL‐1β, IFN‐γ, IL‐4, and IGF1, were significantly reduced in the L. salivarius /3D8‐treated chickens. In summary, our results suggest that L. salivarius expressing 3D8 scFv could be considered a feed additive for improving the growth performance, immune function, and disease resistance of poultry.

中文翻译：

---

将表达 3D8 scFv 的唾液乳杆菌作为饲料添加剂施用可改善鸡的生长性能、免疫稳态和肠道微生物群。

益生菌被定义为以适当的量给药以对宿主动物提供健康益处的活微生物。在本研究中，我们研究了唾液乳杆菌DJ-sa-01 分泌 3D8 单链可变片段 (3D8 scFv) 对鸡生长性能、细胞因子分泌和肠道微生物菌群的影响。实验分为对照组和表达3D8 scFv的唾液乳杆菌实验组。每天给鸡喂食 10 ^{9 个}菌落形成单位 (CFU) 的野生型 (WT)唾液乳杆菌或 3D8 scFv 分泌型唾液乳杆菌，持续 35 天。L. salivarius的管理与施用 WT唾液乳杆菌相比，表达 3D8 scFv 显着改善了鸡的体重。16S 核糖体 RNA 宏基因组分析表明，厚壁菌门、变形菌门、放线菌门和拟杆菌门是两个实验组中的优势门。在属水平上，与 WT唾液乳杆菌组相比，唾液乳杆菌/ 3D8 组中的乳杆菌更丰富 (22.82%) 。在唾液乳杆菌/3D8 处理的鸡中，IL-8、TNF-α、IL-1β、IFN-γ、IL-4 和 IGF1 等细胞因子的血清水平显着降低。总之，我们的结果表明表达 3D8 scFv 的L. salivarius可以被认为是一种饲料添加剂，用于改善家禽的生长性能、免疫功能和抗病性。