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Britain's most popular fruit the banana could help fight deadly diseases such as AIDS and hepatitis C and even flu, a new study found.

Every person, on average, eats 100 kgs of the fruit each year and now scientists have peeled back the secrets of a natural substance that could lead to new treatments.

It works by harnessing the "sugar code" that our cells use to communicate but viruses and other invaders hijack this code.

The new study focused on a protein called banana lectin, or BanLec, that "reads" the sugars on the outside of both viruses and cells.

Five years ago, scientists showed it could keep the virus that causes AIDS from getting into cells - but it also caused side effects that limited its potential use.

(Image: PA)

Now an international team of scientists created a new form of BanLec that still fights viruses in mice, but doesn't have a property that causes irritation and unwanted inflammation.

They succeeded in peeling apart these two functions by carefully studying the molecule in many ways, and pinpointing the tiny part that triggered side effects.

Then, they engineered a new version of BanLec, called H84T, by slightly changing the gene that acts as the instruction manual for building it.

The new version worked against the viruses that cause AIDS, hepatitis C and influenza in tests in tissue and blood samples - without causing inflammation.

H84T BanLec also protected mice from getting infected by flu virus.

Professor of internal medicine Dr David Markovitz at the University of Michigan Medical School said: "What we've done is exciting because there is potential for BanLec to develop into a broad spectrum antiviral agent, something that is not clinically available to physicians and patients right now.

(Image: Getty)

"But it's also exciting to have created it by engineering a lectin molecule for the first time, by understanding and then targeting the structure."

Scientists from Germany, Ireland, Canada, Belgium and the United States worked together over several years to figure out exactly how BanLec worked against viruses, and then to build a better version.

They could then change the gene in a way that fine-tuned the BanLec molecule which kept viruses out of cells but did not trigger the immune system response.

The new version of BanLec has one less tiny spot on its surface for sugars to attach, called a "Greek key" site making it impossible for sugars on the surface of immune system cells called T cells to attach in multiple spots at once and trigger inflammation.

But it still allows BanLec to grab on to sugars on the surface of viruses and keep them from getting into cells.

Prof Markovitz said: "Better flu treatments are desperately needed.

"Tamiflu is only modestly effective, especially in critically ill patients, and influenza can develop resistance to it.

"But we also hope that BanLec could become useful in situations such as emergency pandemic response, and military settings, where the precise cause of an infection is unknown but a viral cause is suspected."

Scientists still don't fully understand all the things that the sugar code controls - but suspect it may be almost as powerful for controlling how our cells work as the DNA code inside cells.

Sugars, and the lectins that attach to them, seem to play a key role in how cells "talk" to one another, call for help, and perform other functions.

The study was published in the journal Cell.