Botulinum toxin, a neurotoxin secreted by the bacterium Clostridium botulinum, is the most poisonous substance known in nature. It takes the injection of just 3 billionths of a gram to kill a 70 kilo adult human.
Botulinum toxin interfere with the nervous system by blocking the release of acetylcholine, the main muscular neurotransmitter. This leads to muscle paralysis and will cause the victim to suffocate as the muscles controlling the heart and lungs give out.
Until recently, seven exotoxins have been identified as secreted by C. botulinum, - A, B, C1, C2, D, E, F and G. People poisoned with these toxins can be treated with monoclonal antibodies (artificial immune proteins) to reverse the toxic effects. Botulinum toxin A is used to induce muscle weakness lasting about six months, which can alleviate issues such as bladder incontinence and is used for cosmetic treatments on facial lines.
In October 2013 it was announced that an eighth type of botulinum toxin, H, had been discovered in the feces of a child suffering from botulism. Genetic sequencing of the bacterial DNA encoding this toxin has revealed that it is part of a separate branch on the botulinum family tree.
Upon the discovery of a new gene, it is common practise that the genetic data is submitted to the public database GenBank. However is has been decided that the coding for toxin H is best kept out of the public domain.
Tests of toxin H antibodies (grown in rabbits) upon mice have shown that, whilst the antibody is capable of protecting against toxin H, a huge dose is needed. Until a better, stronger antibody can be created it various US government agencies have felt that it is in the public interest to limit knowledge of this toxic.
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