Tetanospasmin — key properties: Which statements correctly describe the principal Clostridium tetani toxin responsible for clinical tetanus?

Introduction / Context:
Tetanus results from the action of tetanospasmin, a potent neurotoxin produced by Clostridium tetani under anaerobic conditions in contaminated wounds. Understanding the biochemical nature of the toxin informs prevention and treatment strategies.

Given Data / Assumptions:

• Tetanospasmin is a protein exotoxin.
• It targets inhibitory interneurons, blocking neurotransmitter release and causing spastic paralysis.
• Protein exotoxins can be detoxified (toxoided) to generate protective vaccines.

Concept / Approach:

Evaluate each statement: heat-labile proteins denature with sufficient heat; neurotoxin specifies target tissue action; toxoid formation underlies the tetanus component of DTP/DTaP vaccines. All three statements are true.

Step-by-Step Solution:

Verification / Alternative check:

Clinical prevention relies on toxoid immunization; treatment uses human tetanus immunoglobulin to neutralize circulating toxin, consistent with a protein antigen target.

Why Other Options Are Wrong:

Each single statement is correct but incomplete; the best answer combines all accurate properties.

Common Pitfalls:

Confusing heat-labile exotoxins with heat-stable enterotoxins from other organisms; also, forgetting that antitoxin does not reverse toxin already internalized in neurons.

Final Answer:

All of these