Detection of vaccine antigens on the bacterial surface after cultivation in THB (A) or porcine plasma (B). S. suis strains 10 (cps2), 16085/3b (cps9) and V3117/2 (cps14) were grown until stationary phase and incubated with sera of rabbits immunized with the indicated vaccine antigens. In the next step bacteria were labeled with a fluorescein isothiocyanate (FITC)-labeled anti-rabbit antibody. After fixation with 2% (w/v) paraformaldehyde bacteria were investigated by flow cytometry using a LSR Fortessa (BD Biosciences). Data were analyzed with FlowJo software 10.1r5 (TreeStar, Ashland, OR, USA). As controls, bacteria were measured without incubation in a rabbit antiserum (w/o 1. antibody) or with a rabbit serum collected prior immunization (pre immun). The experiment was repeated three times.