Journal of Vaccines & Vaccination

Prevention of ETEC and STEC infections using recombinant Lactococcus lactis expressing surface nanobodies against F4 and F18 fimbriae

6^th Euro Global Summit and Expo on Vaccines & Vaccination

August 17-19, 2015 Birmingham, UK

Okello E1,2,3, Moonens K1,2, De Kerpel M1,2, Erume J3 and De Greve H1,2

Scientific Tracks Abstracts: J Vaccines Vaccin

Abstract:

Post-weaning diarrhea and edema disease, caused by enterotoxigenic and Shiga toxin producing Escherichia coli (ETEC and
STEC) strains, are important diseases of newly weaned piglets worldwide. We recently demonstrated that ETEC infections
ETEC infections were wide spread among piggeries in Uganda, but the management practices such as extensive antibiotic
prophylaxis and late weaning masked clinical disease outbreaks.The isolates from clinical cases showed extensive resistance
to commonly used antibiotics.To prevent post-weaning diarrhea and edema disease, passive immunisation of weaning piglets
with recombinant Lactoccocus lactis as a probiotic was evaluated as an alternative to antibiotic prophylaxis. The variable
domain of the llama heavy-chain antibodies, named VHHs or nanobodies (Nb), directed against fimbrial adhesions FaeG (F4)
and FedF (F18) were cloned and expressed on the surface of L. lactis. In vitro, the recombinant Nb-expressing L. lactis strains
agglutinated and inhibited adhesion of cognate F4 or F18 E. coli to pig villous preparation. In vivo, the anti-F4 Nb-expressing L.
lactis were protective to weaned piglets against a challenge with an F4-positive ETEC strain. We found that the piglets receiving
the anti-F4 Nb-expressing L. lactis showed a reduced faecal bacterial shedding and an increased immune response against F4
fimbriae. We concluded that the surface nanobodies on L. lactis strains effectively neutralised and abrogated gut colonisation
by E. coli, the first step in disease pathogenesis. The protectiveness of the recombinant L. lactis tested provides a real potential
for passive immunisation that should be explored further.