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Salmonella 'survives on sugar'?

Apparently, the food poisoning bug feeds on glucose to survive as it causes infection. Scientists now claim that it could soon pave the way for a new vaccine against it.
PTI | By HT Correspondent, London
UPDATED ON MAY 25, 2009 07:00 PM IST

Scientists have discovered that the food poisoning bug Salmonella feeds on glucose to survive as it causes infection, a finding which they claim could soon pave the way for a new vaccine against it.

A team in Britain, led by Dr Arthur Thompson from the Institute of Food Research, has carried out a research which has shown for the first time Salmonella's weakness for sugar, the Infection and Immunity journal reported.

"This is the first time that anyone has identified the nutrients that sustain Salmonella while it is infecting a host's body," Dr Thompson said.

Salmonella food poisoning causes infection in around 20 million people worldwide each year and is responsible for about 200,000 human deaths. It also infects farm animals and attaches to vegetables.

During infection, Salmonella bacteria are engulfed by immune cells designed to kill them. But, instead the bacteria multiply.

As Salmonella must acquire nutrients to replicate, the scientists focused on glycolysis, the process by which sugars are broken down to create chemical energy. They constructed Salmonella mutants unable to transport glucose into the immune cells they occupy and unable to use glucose as food.

These mutant strains lost their ability to replicate within immune cells, rendering them harmless. "Our experiments showed that glucose is the major sugar used by Salmonella during infection," Dr Thompson said.

The mutant strains still stimulate the immune system, and the scientists have filed patents on them which could be used to develop vaccines to protect people and animals against poisoning by fully virulent salmonella.

Glycolysis occurs in most organisms including other bacteria that occupy host cells. Disrupting how the bacteria metabolise glucose could therefore be used to create vaccine strains for other pathogenic bacteria, including superbugs.

The harmless strains could also be used as vaccine vectors. For example, the flu gene could be expressed within the harmless Salmonella strain and safely delivered to the immune system.

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