( Two enzymes in meningitis bacteria whic...)Scientists identify specific enzymes that make meningitis hard to fight

The study found that the two enzymes - which have distinct functions - work together to hamper the body's efforts to fight off the disease. Together they repair damage done to the meningitis bacteria's DNA by the body's white blood cells, which are sent to fight the infection.

Understanding the part these enzymes play in the process that enables the bacteria to elude the body's natural defences could eventually help scientists develop novel new treatments for meningitis and the septicaemia it can cause. Both are extremely serious conditions with a high mortality rate, which take hold quickly and are difficult to treat - sometimes resulting in extreme measures such as limb amputation.

When the meningitis bacteria enter the bloodstream, the body's natural defences send white blood cells to fight the infection. They ingest the bacteria and subject them to oxidative stress. Oxidative stress damages the base chemical compounds of the bacteria's DNA. This should lead to cell death and the defeat of the bacteria. However, the virulent meningitis bacteria are able to repair this harmful damage and are therefore unaffected by the body's defences.

The research team found that the two enzymes essential to the bacteria's repair mechanism are AP endonuclease and 3'-phosphodiesterase. Contrary to the scientists' expectations, these two enzymes carry out separate functions in the DNA repair process.

Professor Paul Freemont from Imperial's Division of Molecular Biosciences explains: "Scientists have long understood that the secret of meningitis' virulence lies in its ability to rearrange its DNA and thus change its external appearance to the body's immune system. Significantly our research has now demonstrated that the ability of meningit
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Source:Imperial College London