Neutralization of Hemolytic Activity of Hemolysin II and Cytotoxin K2 of Bacillus cereus by Antibodies

Abstract Objective: Bacillus cereus, a gram-positive bacterium widespread in nature, can cause toxic infections in humans. Key virulence factors include hemolysin II (HlyII) and cytotoxin K2 (CytK2), which belong to the group of β-pore-forming toxins. The toxic effect occurs when the water-soluble monomeric forms of the toxins secreted by the bacterium oligomerize to form pores that disrupt the permeability of the cell membrane, leading to cell lysis. Methods: The study examined the suppression of toxic activity HlyII and CytK2 in vivo and the effect of HP-5 neutralizing antibodies on the CytK2. Results and Discussion: Neutralizing antibodies against hemolysins HlyII and CytK2 have been shown not to interfere with the oligomerization of monomers in the presence of the target cell membrane. Monoclonal antibodies that neutralize the hemolytic activity of CytK2 block the pore formed by the toxin on the target cell membrane, as do antibodies against the large C-terminal fragment of the HlyII strain, which specifically neutralize its effect. Using a mouse model, the ability of antibodies to neutralize the action of HlyII and CytK2 was demonstrated. Conclusions: The neutralizing antibodies being studied may form the basis for the development of therapeutic agents for the treatment of diseases caused by B. cereus.