A tropical disease that infects millions of people annually is caused by a newly discovered bacterial toxin that shuts down a host's capacity to produce proteins, the essential building blocks of life, an international team of scientists announced Thursday.
Melioidosis, caused by air or water borne infections, is also known as the Vietnam time bomb since the causative bacteria typically incubates in people, taking years and sometimes even decades to sicken hosts.
The Burkholderia pseudomallei bacteria that cause the bomb produce a previously-unknown toxin that wreaks havoc on cells, according to research published in the online edition of Science on Thursday.
The toxin gives researchers a new target to tackle a disease that kills 20 percent to 40 percent of its victims in Australia and Thailand.
This disease is an everyday reality for many people living in the endemic areas and our findings will allow us to test if an inactivated toxin might be effective as a component of a vaccine, University of Exeter microbiologist Rick Titball and co-author, said in a statement.
The bacteria are rare in the U.S. and Europe and are more commonly found in tropical regions such as Southeast Asia and Northern Australia.
The research group identified a toxin that killed mice. Without knowing how the toxin acted, the group reconstructed the molecular structure of the toxin and found its lethal mechanism.
The information gathered from the structure suggested that the protein was a previously unsuspected toxin and sparked a search for its mode of action, David Rice, structural biologist at University of Sheffield, U.K. and lead author, said in a statement.
This eventually led to the discovery of how it prevents human cells from making proteins and helped us understand how it causes death, he said.
The researchers found that the toxin inhibits the molecular machine needed to produce proteins, essential for life.
One question remains: how and why do the bacteria incubate in hosts before unleasing melioidosis. Many Vietnam veterans likely carry the bacteria, and knowing more about the toxin it creates may eventually help the medical community develop a melioidosis treatment, according to Stuart Wilson, a molecular biologist at University of Sheffield and a co-author on the paper.
An inactive form of the toxin might be useful in production of a vaccine against (the disease), Wilson wrote in an email.
Wilson said the toxin the bacteria produce is so powerful that it takes only 10 micrograms to kill a mouse - an amount far too little for the naked eye to see.
The bacterium decides when to make the toxin - it is this decision which is probably important in disease progression, he said.
A useful vaccine is still some way off, but, [if there] were one to emerge, it would be very significant, he said.