Western blotting was performed as described before [29 (link)]. Horseradish peroxidase (HRP)-conjugated 6×His-tag antibody (Abcam, Cambridge, UK) was diluted 1,000 times to detect the His-tagged proteins. The B. abortus monoclonal antibody (Thermo Fisher Scientific, Waltham, USA) or Y. enterocolitica O:9 monoclonal antibody (Fitzgerald, Acton, USA) was diluted 100 times to detect the polysaccharides of the glycoproteins. HRP-conjugated goat anti-mouse IgG (Abcam, Cambridge, UK) was used as the secondary antibody.