New method to generate enzymatically deficient Clostridium difficile toxin B as an antigen for immunization

Area of Science:

• Microbiology
• Toxicology
• Biochemistry

Background:

• Large clostridial cytotoxins, including Clostridium difficile toxins A and B, monoglucosylate Rho GTPases.
• This enzymatic activity is crucial for their cytotoxic effects.

Purpose of the Study:

• To develop a novel detoxification procedure for large clostridial cytotoxins.
• To investigate the enzyme activity and antigenic properties of modified toxins.

Main Methods:

• Treatment of toxins A and B with UDP-2', 3'-dialdehyde to induce alkylation.
• Assessing toxin inactivation and competition with native toxins for cell receptor binding.
• Generating antibodies against native and alkylated toxins and evaluating their neutralizing capabilities.

Main Results:

• UDP-2', 3'-dialdehyde treatment successfully alkylated toxins A and B, blocking their enzyme activity.
• Alkylation occurred in the catalytic domain, as evidenced by protection with UDP-glucose and competition for cell receptors.
• Alkylated toxins elicited antibodies targeting the receptor binding domain, while formaldehyde treatment yielded antibodies against both domains.
• Antibodies against the catalytic domain inhibited enzyme activity, but only antibodies against the receptor binding domain protected intact cells from Toxin B.

Conclusions:

• Alkylation is an effective detoxification strategy for large clostridial cytotoxins.
• The catalytic domain of these toxins is concealed under native conditions.
• Antibody-mediated protection depends on the target domain and cellular localization.