IMMUNE SERA TO INDIVIDUAL BORRELIA-BURGDORFERI ISOLATES OR RECOMBINANT OSPA THEREOF PROTECT SCID MICE AGAINST INFECTION WITH HOMOLOGOUS STRAINS BUT ONLY PARTIALLY OR NOT AT ALL AGAINST THOSE OF DIFFERENT OSPA OSPB GENOTYPE/

The outer surface proteins OspA and OspB of Borrelia burgdorferi have recently been demonstrated to be major target proteins for protective antibodies in mice against infection with the homologous spirochaetal strain. However, it has become clear from a variety of studies that B. burgdorferi isolates of different geographical origin and/or sources are heterogeneous and that they can be divided into at least six subgr oups according to their distinct OpsA/OspB genotypes. In order to anal yse cross-protection between these subgroups we have now generated imm une sera to various isolates of B. burgdorferi with different OspA/Osp B genotypes. We show that passive immunization with antisera specific for whole spirochaetes or recombinant OspA of one spirochaetal isolate protects severe combined immunodeficiency mice against infection with strains of the corresponding OspA/OspB genotype but only partially or not at all against infection with isolates expressing distinct OspA/O spB genotypes. The incomplete protection mediated by individual antise ra against independent isolates of B. burgdorferi suggests that an eff ective subunit vaccine against Lyme disease should consist of a mixtur e of OspA structures covering the heterogeneity of this protein within the species B. burgdorferi.