Researcher wants to prevent deadly outbreaks of cholera

(Edmonton) Just over a year after the earthquake in Haiti killed 222,000 people, there's a new problem that is killing Haitians: a cholera outbreak has doctors in the area scrambling and the water-borne illness has already claimed 3,600 lives, say officials with Medicin Sans Frontieres (Doctors Without Borders).

"There's no separation of drinking water and sewage; that's the problem in Haiti," said Stefan Pukatzki, a bacteriologist in the Faculty of Medicine & Dentistry at the University of Alberta. "There's raw sewage in the streets and that's where people are getting their drinking water, so this is a very vicious cycle and it spreads like wildfire."

Cholera becomes a major problem in these areas because those infected shed about 20 litres of diarrhea and, with no access to fresh water, the patients soon die from dehydration.

Pukatzki is hoping his lab can help put a stop to these deadly outbreaks in the future.

His lab studies Vibrio cholerae, the bacteria that makes up the disease, and he has discovered how it infects and kills other bacteria and host cells. This discovery, published in November's Proceedings of the National Academy of Sciences, could explain how this organism survives between epidemics. Pukatzki says Vibrio cholerae lives in fresh water mix between epidemics and no one has known how it competed and survived with other bacteria in the water.

A better understanding of how this organism infects cells means Pukatzki may be able to devise novel strategies to block the function.

Pukatzki discovered that Vibrio cholerae uses molecular nano-syringes to puncture host cells and secrete toxins straight in to the other organism; this is called the type six secretion system.

"Vibrio cholerae uses these syringes so when it comes in contact with another bacteria, like E. coli, which is a gut bacterium, it kills it," said Pukatzki. "That's a novel phenomenon. We knew it competed with cells of the immune system but we didn't know it was able to kill other bacteria.

"Keep in mind these syringes are sitting on the outside of the bacterium so they make good vaccine targets," said Pukatzki. "That's actually better because you could either inhibit the type six function or you could induce an immune response with these components that are sitting on the outside."

Pukatzki is excited because the type six secretion system isn't unique to Vibrio cholera; it is found in most major pathogens.

"We really think that even though this pathway is important for cholera, I think that whatever we find we can apply to other diseases as well because they're so highly conserved," said Pukatzki.

Pukatzki's lab is now looking to get a better understanding of this mechanism and continue working toward a potential pharmaceutical target.

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