Botulinum Toxin and Its Biological Significance: A Review

Abstract

Botulism is a severe neuroparalytic bacterial disease caused by Gram positive, anaerobic, spore-forming microorganisms, Clostridium botulinum, referred to as Botulinum neurotoxin (BoNT) producing bacteria. The objective of this paper is to review botulinum toxin and its biological significance. This bacteria can produce seven types of toxins (A - G) known as BoNT. BoNT is highly potent preformed toxin that affects humans, all warm-blooded animals and fishes due to consumption of contaminated silage, carcass, water, industrial by product and canned foods like meat, milk, fruits and vegetables. Botulism is an important disease in the world, particularly where stock graze under range conditions and are subject to periods of protein and phosphorous deficiency. There is no geographical limitation for botulism because sporadic outbreaks occur in the most countries. The main route of transmission of botulism is by oral ingestion and wound infection with spore. The clinical signs occur within 24 hour up to 17 days. BoNT contain zinc endopeptidase that blocks vesicle of acetylcholine binding with the terminal membrane of the motor neuron and causes flaccid muscle paralysis with lateral recumbency, generalized muscle weakness and dysphagia. Finally results in death due to respiratory arrest, paralysis of pharyngeal and diaphragmatic muscles. There is no specific lesion during postmortem examination but may be seen in chronic case. Diagnosis is based on clinical signs and laboratory examination like, ELISA (Enzyme Linked Immuno Sorbent Assey), MPT (Mouse Protection Test) and culture for isolation of bacteria. Although this toxin in animals represents a serious environmental and economic concern because of the high mortality during the outbreak, it provides some biological significance after extraction by genetic recombination like in cosmetics, chemotherapy and biological weapons. There is no effective treatment but ampicillin is used as antibiotic. Prevention by polyvalent vaccine and proper feeding management is better than treatment. Therefore it recommended that the farmers should store animals feed with proper ventilation to avoid multiplication of bacterial spore