No abstract

Monoclonal antibodies directed against the major Borrelia burgdorferi flageHar protein, the 41-kilodalton (kDa) protein flagellin, were used to monitor cloning and expression of the flagellin gene from a Borrelia burgdorferi genomic library. The structure of the gene was analyzed, and recombinant nonfusion flagellin was produced in Escherichia coli. A DNA sequence analysis of the 41-kDa flagellin gene revealed the presence of an open reading frame that encoded a protein having 336 amino acid residues and a calculated molecular mass of 35.8 kDa, indicating that there was posttranslational modffication of the natural 41-kDa flagellin protein. Upstream from the AUG start codon sequence we identified motifs corresponding to consensus procaryotic promotor elements which could be utilized by the cloned flagellin gene when it was expressed in E. coli MC1061. The deduced flagellin protein sequence exhibited high levels of homology to sequences of flagellin proteins from Bacillus subtilis and Salmonella typhimurium. The levels of sequence similarity for the aminoand carboxyterminal portions were about 65 and 56%, respectively. DNA sequence information on the flageilin gene was used to design oligonucleotides for gene amplification by the polymerase chain reaction method, and by using this method 0.01 pg of Borrelia burgdorferi DNA could be detected. Our results provide a basis for further biochemical analysis of the 41-kDa flageilin protein, investigation of the role of this protein in host-pathogen interactions, and development of a standardized reagent for diagnostic systems for Borrelia burgdorferi infections.

Previously we have found that sera from immunocompetent mice infected either naturally by ticks or experimentally with low numbers of Borrelia burgdorferi ZS7 bacteria lack OspA-and OspB-specific antibodies but confer optimal protection on severe combined immunodeficiency mice against challenge with spirochetes (U. E.