Orally Fed Recombinant Lactococcus lactis Displaying Surface Anti-Fimbrial Nanobodies Protects Piglets against Escherichia coli Causing Post-Weaning Diarrhea

Post-weaning diarrhea (PWD) and edema disease (ED), caused by enterotoxigenic Shiga toxin producing Escherichia coli (ETEC STEC) strains, are important diseases of newly weaned piglets worldwide. The objective this study is to develop a passive immunization strategy protect against PWD ED using recombinant Lactococcus lactis added piglet diet at weaning. Variable Heavy chain domains antibodies (VHHs) or Nanobodies (Nbs), directed the fimbrial adhesins FaeG (F4 fimbriae) FedF (F18 E. were cloned expressed on surface L. lactis. In vitro, strains agglutinated inhibited adhesion cognate F4 F18 fimbriae expressing pig villous preparation. vivo, anti-F4 protected challenge with an F4-positive ETEC strain. Piglets supplemented oral showed reduced fecal shedding. We concluded that neutralized targeted abrogated gut colonization, first step in pathogenesis. As proof concept, we demonstrated potential as viable alternative antibiotic prophylaxis preventing piglet-post-weaning diarrhea.