Fig. 3: Characterization of spirulina-expressed, anti-campylobacter VHH.

a, Epitope mapping of VHH interaction with FlaA. Peptides derived from the D2/D3/D4 region of FlaA (amino acids 177–482) were panned by phage display. Enriched clones were sequenced after two or three rounds of panning. Results represent average positional frequency observed in two independent panning experiments. b, CEIA quantification of aa682 expressed in SP1182. Clarified lysate from SP1182 was displayed on a Jess system, with an anti-His-tag antibody used for detection. A single peak was observed at the predicted MW of 54.8 kDa. Using a standard curve of purified protein (Extended Data Fig. 7), the amount of soluble aa682 was ~3% of total biomass. Result is representative of dozens of independent experiments. c, Binding kinetics of spirulina-expressed aa682 with recombinant FlaA measured by BLI. Streptavidin-coated biosensors were loaded with biotinylated FlaA, and association and dissociation were measured. Curve fitting was performed using a 1:1 binding model. d, Binding of VHH to intact C. jejuni. Soluble extracts from spray-dried spirulina biomass containing an irrelevant VHH (SP257) or FlagV6-MBP (SP526) were incubated with C. jejuni 81–176 and stained with a fluorescently labelled anti-His-tag antibody. Fluorescence was measured in the allophycocyanin channel (APC-A) by flow cytometry. e, Inhibition of C. jejuni motility by aa682. Two strains of C. jejuni (81–176 and CG8421) were grown on soft agar plates in the presence of aa682 or an irrelevant VHH control (PP496). Halo areas (mean ± s.d.) were measured for triplicate samples at either 40 h (81–176) or 66 h (CG8421) after plating.