Stabilisation of the gut microbiota and reduction of ETEC proliferation in piglets using two bivalent VHH constructs

Post-weaning diarrhea (PWD) in piglets presents a widespread problem in industrial pig production and is caused by enterotoxigenic E. coli (ETEC) strains. Current solutions, such as antibiotics and medicinal zinc oxide, are unsustainable and face bans, resulting in a dire need for novel solutions. Thus, in this study, we propose and evaluate a protein-based feed additive, comprising bivalent heavy chain variable domain (VHH) constructs. We demonstrate in vitro that these constructs bind to ETEC toxins and fimbriae, whilst not affecting bacterial growth rate. Furthermore, in a pig study, we show that oral administration of these constructs after ETEC challenge reduced ETEC proliferation, and potentially stabilised the commensal microbiota when compared to challenged control piglets. These data suggest that such VHH constructs may find utility in industrial pig production as a feed additive for tackling ETEC and reducing the risk of PWD in piglet populations.

仔猪断奶后腹泻（Post-weaning diarrhea, PWD）是工业化生猪养殖中普遍存在的难题，由产肠毒素大肠杆菌（enterotoxigenic E. coli, ETEC）菌株引发。当前主流解决方案如抗生素与药用氧化锌均不可持续且面临禁用，因此亟需开发新型替代方案。为此本研究提出并评估了一种基于蛋白质的饲料添加剂，其有效成分为二价重链可变结构域（VHH）构建体。体外实验证实，该构建体可特异性结合ETEC毒素与菌毛，且不会影响细菌生长速率。此外生猪活体试验结果显示，相较于ETEC攻毒对照组仔猪，攻毒后口服该构建体可抑制ETEC增殖，并可能维持共生菌群稳态。上述数据表明，此类VHH构建体可作为饲料添加剂应用于工业化生猪养殖，用于防控ETEC感染并降低仔猪群体的断奶后腹泻发病风险。