Production of serotype C specific and serotype C/D generic monoclonal antibodies using recombinant HC and HN fragments from Clostridium botulinum neurotoxin types C1 and D

Sequence variability of Clostridium botulinum serotypes C and D is particularly complex. Some serotype C and D strains have unique gene structures that encode mosaic isoforms of botulinum neurotoxin (BoNT) containing components of both BoNT type C1 (BoNT/C1) and BoNT type D (BoNT/D). Such sequence variability and the potential for cross neutralisation must be taken into consideration when developing serotype C and D detection and identification assays. Three fusion proteins containing either a fragment from the carboxyl-terminal domain of the heavy chain (HC) of BoNT/C1 (strain 573), a fragment from the HC of BoNT/D (strain BVD/-3) or a fragment from the amino-terminal domain of the heavy chain (HN) of BoNT/C1 (strain 573) were expressed in Escherichia coli, and administered as immunogens to mice. Monoclonal antibodies (mAbs) against the recombinant BoNT fragments were prepared by three fusions. MAbs recognising native BoNT/C1 and BoNT/D were detected by enzyme-linked immunosorbent assay (ELISA). Nine monoclonal antibodies (mAbs) were produced, six of which recognised a BoNT fragment that is highly conserved across all serotype C and D producing strains. We conclude that these mAbs and this approach to mAb production may facilitate the development of immunological diagnostic techniques that are not constrained by the existence of mosaic isoforms for the detection and identification of serotypes C and D.