Structural insight in the inhibition of adherence of F4 fimbriae producing enterotoxigenic Escherichia coli by llama single domain antibodies.

Kristof Moonens,Maia De Kerpel,Els Pardon,Henri De Greve,Emmanuel Okello,Imke Van Den Broeck,Han Remaut

doi:10.1186/s13567-015-0151-x

Abstract

Enterotoxigenic Escherichia coli that cause neonatal and post-weaning diarrhea in piglets express F4 fimbriae to mediate attachment towards host receptors. Recently we described how llama single domain antibodies (VHHs) fused to IgA, produced in Arabidopsis thaliana seeds and fed to piglets resulted in a progressive decline in shedding of F4 positive ETEC bacteria. Here we present the structures of these inhibiting VHHs in complex with the major adhesive subunit FaeG. A conserved surface, distant from the lactose binding pocket, is targeted by these VHHs, highlighting the possibility of targeting epitopes on single-domain adhesins that are non-involved in receptor binding.

Highlights

Enterotoxigenic Escherichia coli that cause neonatal and post-weaning diarrhea in piglets express F4 fimbriae to mediate attachment towards host receptors
Introduction, methods and results F4 fimbriae are expressed on the cell surface of enterotoxigenic E. coli (ETEC) to mediate attachment towards carbohydrate receptors localized on the enterocytes of piglets [1]
In a hemagglutination based assay purified monovalent VHH were unable to inhibit the interaction of guinea red blood cells and F4 fimbriated bacteria

Summary

Introduction

Enterotoxigenic Escherichia coli that cause neonatal and post-weaning diarrhea in piglets express F4 fimbriae to mediate attachment towards host receptors. All three inhibitory VHHs interact with conserved epitopes on the FaeG surface (Figure 1A).

Results

Conclusion