Epitope mapping of botulinum neurotoxins light chains

Botulinum neurotoxins (BoNTs) are listed among the most potent biothreat agents. Simultaneously, two out of seven known serotypes of these toxins are used in medicine and cosmetics. This situation calls for development of detailed epitope maps of these toxins. Such maps will help to develop new ways for decreasing damage caused by these toxins if they were to be used as weapons while retaining the therapeutic effect of these toxins used as medicine. Here, we used a library of random fragments of DNA encoding the catalytic domain of botulinum neurotoxin serotype A to identify short epitope-forming sequences. We demonstrated that knowledge of such sequences in a BoNT of one serotype can be used for identification of epitope-forming sequences in other serotypes of BoNTs. We also demonstrated a serodiagnostic value of identified sequences and their ability to retain epitope-specific structures and trigger production of corresponding antibodies, even when they are transferred into a background of a completely alien carrier protein. ► Random fragments of BoNT/A light chain were screened with rabbit anti-BoNT/A serum. ► Four separate epitope-forming regions were determined. ► Epitopes in other serotypes were determined by alignment of sequences. ► Epitopes retain their structure even when incorporated into other proteins. ► α-toxin of Clostridium perfringens can carry foreign polypeptides outside of the Escherichia coli cell.