Surface binding of spirochetes to determine vaccine-induced antibodies. The antibodies generated by the chimeric vaccine candidates were tested by surface binding assay. The binding of vaccine-induced antibodies to OspA of the corresponding serotype was compared to the binding of antibodies generated by the respective FL-OspA. The surface binding assay was performed with B. burgdorferi OspA ST1 ZS7, B. afzelii OspA ST2 Pra10, B. garinii OspA ST3 PFr, B. bavariensis OspA ST4 PFin, B. garinii OspA ST5 PHei, and OspA ST6 KL11. The results are presented as fluorescence intensity.