Monoclonal antibodies with in vitro borreliacidal activities define the outer surface proteins A and B of Borrelia burgdorferi.

Thirteen monoclonal antibodies (mAb) were produced against Borrelia burgdorferi strains B31 and PKa. Five mAb recognized the outer surface protein OspA (relative molecular mass (M(r)) 31,000) and four OspB with an M(r) of 34,000. Two of these mAb were directed against flagellin with an M(r) of 41,000, and the remaining two against the antigens of B. burgdorferi with M(r) values of 19,000 and 17,000. Immunoblot and immunofluorescence studies with these mAb on five isolates of B. burgdorferi revealed differences in the individual antigenic epitopes of OspA and OspB. OspA and OspB specific mAb showed a borreliacidal activity in vitro. These antibodies were additionally reactive in haemagglutination and immunofluorescence assays. Enzymatic digestion investigations on intact borreliae suggest that the antigenic determinants of mAb with borreliacidal activity are located in the peptide chain of OspA and OspB.