The present invention relates to isolated nucleic acid molecules which encode a protein, isolated nucleic acid molecules which encode a hyperimmune serum reactive antigen, a vector which comprises such nucleic acid molecule, a host cell comprising such vector, a hyperimmune reactive antigen from Borrelia species, proteins which are preferably hyperimmune serum reactive antigens, hyperimmune serum reactive antigens, antigens, a process for producing such proteins, hyperimmune serum reactive antigens or antigens, a process for producing a cell which expresses such protein, hyperimmune serum reactive antigen or antigen, an antibody binding to such protein, hyperimmune serum reactive antigen or antigen, a hybridoma cell producing such antibody, methods for producing such antibody, a pharmaceutical composition comprising such nucleic acid molecule, protein, hyperimmune serum reactive antigen, antigen or antibody, the use of such nucleic acid molecule, protein, hyperimmune serum reactive antigen, antigen or antibody for the manufacture of a medicament, methods for identifying an antagonist capable of reducing or inhibiting the interaction activity of such protein, hyperimmune serum reactive antigen or antigen, methods for diagnosing an infection and methods for the treatment of an infection. More specifically such proteins, hyperimmune serum reactive antigens or antigens are produced by or associated with bacterial pathogens causing Lyme disease or bacterial infections caused by Borrelia burgdorferi s.l.