Interaction of Monoclonal Antibodies Against Individual Parts of Bacillus cereus Hemolysin II with a Pore Formed by the Toxin

Objective: One of the key pathogenic factors of Bacillus cereus is hemolysin II (HlyII), secreted as water-soluble monomers. HlyII belongs to the group of β-pore-forming toxins, which are characterized by oligomerization of monomers upon interaction with the cell membrane, followed by the formation of ion channels. The objective of this work was to identify the membrane-bound form of the key virulence factor of B. cereus—HlyII. Methods: A method for identifying the membrane-bound form of HlyII using immunoprecipitation has been developed. Results and Discussion: Screening of monoclonal antibodies against various regions of HlyII upon interaction with its membrane-bound form demonstrated a change in the epitope structure of the toxin during pore formation. It has been shown that the C-terminal domain of HlyII is not involved in the formation of the transmembrane channel, unlike the regions of HlyII located proximally relative to this domain. Conclusions: The obtained results indicate conformational changes in HlyII during pore formation, which is significant for the development of drugs that neutralize its effect.