F4- and F18-positive enterotoxigenic Escherichia coli (ETEC) are well-known pathogens able to cause a severe swine disease with a worldwide economically importance in pig production. Vaccination of piglets with an oral live bivalent F4/F18 Escherichia coli vaccine has shown some promise and efficacy results in preventing ETEC post weaning diarrhoea (PWD); however, currently, there is a lack of knowledge on its effect on the intestinal microbial community. Furthermore, is not known if the effect of vaccination on gut eubiosis can vary according to pig genetic susceptibility to ETEC F4 and F18. The aim of this study is to evaluate the effect of an E. coli bivalent vaccine and the potential influence of the host genetic susceptibility to ETEC growth performance and faecal microbial profile of healthy piglets around weaning. A total of 288 healthy piglets at 26 days of age (d0; weaning) were divided into two different groups balanced for body weight: i) vaccine (VAX: 6.33 kg) and control (CO: 6.45 kg). At d0 VAX group was orally inoculated with 2 mL of live non-pathogenic E. coli O8:K87 (F4ac-positive) and O141:K94 (F18ac positive) vaccine (Coliprotec F4/F18; Prevtec Microbia an Elanco Company), while CO was orally inoculated with 2 mL of sterile water. At d0 and 18 days later (d18), piglets were individually weighed, and a faecal sample was collected for microbial profile of V3-V4 regions of the 16S rRNA gene using MiSeq Illumina platform. Bristles were collected to determine the genetic ETEC susceptibility by genotyping analysis of MUC4 and FUT1 polymorphisms. No effect of vaccination and genetic susceptibility was observed on growth performance. The vaccination modulated the faecal microbial composition, reducing the alpha diversity indices (P<0.05) and affecting the beta diversity (R²=0.02; P = 0.05). VAX was discriminated from CO by beneficial bacteria genera including Dialister, Prevotella, Blautia, Ruminiclostridium, Parabacteroides and Faecalibacterium. No interaction between vaccination and animal genetic susceptibility to ETEC was observed. F4 resistant genotype showed a higher alpha diversity index than the susceptible ones pre- and post-weaning (P< 0.05). These findings contributed to the body of knowledge regarding the beneficial effect of oral live bivalent F4/F18 E. coli vaccine on piglets’ gut homeostasis resulting in improved gut eubiosis.

F4-和F18阳性肠毒素大肠杆菌（ETEC）是众所周知的病原体，能够引起严重的猪病，在养猪生产中在世界范围内具有重要的经济意义。用口服活二价F4 / F18大肠杆菌疫苗对仔猪进行疫苗接种已显示出在预防断奶后腹泻（PWD）中ETEC方面的前景和功效。但是，目前尚缺乏有关其对肠道微生物群落影响的知识。此外，尚不清楚疫苗接种对肠道尤斯病的影响是否会根据猪对ETEC F4和F18的遗传易感性而变化。这项研究的目的是评估大肠杆菌的效果双价疫苗以及宿主遗传易感性对断奶前后健康仔猪ETEC生长性能和粪便微生物谱的潜在影响。将总共​​288只26天大的健康仔猪（d0；断奶）分为体重平衡的两个不同组：i）疫苗（VAX：6.33千克）和对照组（CO：6.45千克）。在第0天，VAX组口服接种2 mL活的非致病性大肠杆菌O8：K87（F4ac阳性）和O141：K94（F18ac阳性）疫苗（Coliprotec F4 / F18； Prevtec Microbia属于Elanco公司），同时用2 mL无菌水口服接种CO。在第0天和第18天（第18天），分别对仔猪称重，并使用MiSeq Illumina平台收集粪便样品以检测16S rRNA基因的V3-V4区域的微生物谱。通过对MUC4和FUT1多态性进行基因分型分析，收集鬃毛以确定ETEC的遗传易感性。没有观察到疫苗接种和遗传易感性对生长性能的影响。疫苗接种调节了粪便的微生物组成，降低了α多样性指数（P <0.05）并影响了β多样性（R ^2）= 0.02; P = 0.05）。VAX通过有益细菌属（包括Dialister，Prevotella，Blautia，Ruminiclostridium，Parabacteroides和Faecalibacterium）与CO区分。没有观察到疫苗接种和动物对ETEC的遗传易感性之间的相互作用。F4抗性基因型比断奶前和断奶后的易感基因型表现出更高的α多样性指数（P <0.05）。这些发现促进了关于口服活二价F4 / F18大肠杆菌疫苗对仔猪肠道稳态的有益作用的知识体系，从而改善了肠道的优生性。