Botulinum toxin serotypes: A, B and others
Quick facts
- Definition
- Variants of botulinum neurotoxin, classified by immune reaction and by the target protein.
- Serotypes described
- A, B, C, D, E, F and G, with other variants described more recently.
- Aesthetic use
- In HOF practice serotype A predominates; B has more limited use.
- Molecular target
- A cleaves SNAP-25; B cleaves VAMP (synaptobrevin).
- Point of attention
- Units from different products are not interchangeable.
A serotype is a classification of botulinum toxins based on how the immune system recognizes them. Serotypes are identified by letters: A, B, C, D, E, F and G, with other variants described later. All of them are neurotoxins produced by bacteria of the genus Clostridium and block the release of acetylcholine, but each one cleaves a different target protein inside the nerve terminal.
Which serotypes matter in HOF?
In aesthetic and therapeutic practice, serotype A is the most widely used. Serotype B also has clinical use, though a limited one, and the others are generally the subject of research. Serotypes A, B, E and F affect humans in botulism, while C and D mainly affect animals.
| Serotype | Target protein | Use |
|---|---|---|
| A | SNAP-25 | Main one in aesthetics and in clinical practice |
| B | VAMP (synaptobrevin) | More limited use |
| C | Syntaxin and SNAP-25 | Mainly research |
| E and F | SNAP-25 (E) and VAMP (F) | Research |
Why does the difference matter in the clinic?
First, because onset time, duration and spread can vary between serotypes and between products of the same serotype. Second, because a patient who stops responding to a product because of neutralizing antibodies may, at the physician's discretion, be evaluated for another alternative. Third, because the formulation (whether or not the accompanying protein complex is present) is a topic of technical discussion.
What does not apply to the patient
Patients often ask "which toxin is the best". The honest answer is that the choice depends on registration in good standing with Anvisa (Brazil's health regulatory agency), traceability, the indication and the professional's experience, not on a preference list. Checking where the product comes from is part of safety, together with the cold chain and health registration.
Relation to treatment planning
Even without getting into dosing, understanding serotypes helps you read the package insert, record the product in the patient record and explain what changes when switching products (without citing brand names in public material). The final decision rests with the qualified professional, after assessment and according to the rules of their professional board. Toxin spread is another concept that changes from product to product.
Also called: types of botulinum toxin, serotypes.
Frequently asked questions
Can I convert units between two toxin products?
Not directly. Each product has its own potency and its own measurement method, and conversion by table is a matter of debate. The dose follows the package insert of the chosen product and the professional's judgment.