Thursday 30 July 2015

Bacteria turned into 'silver bullet' to combat flu

Bacteria normally found in yogurt have been turned into "silver bullets" that can destroy viruses and could provide a cure for the common cold.

Woman sneezing
Researchers believe the new technique could help to combat viruses such as influenza and those responsible for causing the common cold Photo: ANDREW CROWLEY

Scientists have discovered that they can attach tiny studs of silver onto the surface of otherwise harmless bacteria, giving them the ability to destroy viruses.

They have tested the silver-impregnated bacteria against norovirus, which causes winter vomiting outbreaks, and found that they leaves the virus unable to cause infections.

The researchers now believe the same technique could help to combat other viruses, including influenza and those responsible for causing the common cold.

Professor Willy Verstraete, a microbiologist from the University of Ghent, Belgium, who unveiled the findings at a meeting of the Society for Applied Microbiology in London last week, said the bacteria could be incorporated into a nasal spray, water filters and hand washes to prevent viruses from being spread.

He said: "We are using silver nanoparticles, which are extremely small but give a large amount of surface area as they can clump around the virus, increasing the inhibiting effect.

"There are concerns about using such small particles of silver in the human body and what harm it might cause to human health, so we have attached the silver nanoparticles to the surface of a bacterium. It means the silver particles remain small, but they are not free to roam around the body."

The bacteria used, Lactobacillus fermentum, is normally considered to be a "friendly" bacteria that is often found in yogurts and probiotic drinks that can help to aid digestion.

The researchers found that when grown in a solution of silver ions, the bacteria extrete tiny particles of silver, 10,000 times smaller than the width of a human hair, which stud the outside of the cells.

Although the bacteria eventually die as a result of the silver, they remain intact and the dead cells carrying the silver particles can then be added to solutions to create nasal sprays or handwashes.

The researchers also found they could be fixed onto other surfaces such as water filters or chopping boards, which can harbour viruses.

Norovirus typically causes 90 per cent of the gastroenteritis cases around the world and is normally spread through poor hygiene or in contaminated food.

Last winter it affected an estimated one million people in England and Wales and forced many hospital wards to be closed.

Influenza is a respiratory infection that normally spreads through the air when infected individuals sneeze and it is breathed in by those around them. Although there are some drugs to treat flu viruses, they are not commonly prescribed. Nasal sprays carrying silver studded bacteria might provide an alternative, according to Professor Verstraete.

Silver nanoparticles are already used in antimicrobial fabrics for sports wear clothing as they can help to reduce the growth of bacteria that can lead to the clothes smelling.

But there have been widespread concerns about applying such tiny particles in ways that could lead to them getting inside the human body.

Silver is already known to cause damage to the liver, kidneys and lungs in large enough amounts and there are fears that the small size of the particles could allow it to pass into other parts of the body and cause harm.

Professor Verstraete, however, claims that by attaching the silver to the outside of the Lactobacillus fermentum bacteria, the silver is fixed onto a larger object that cannot pass into other parts of the body.

He is now working with drug giants Janssen, and Johnson and Johnson to further develop the technology to tackle other viruses.

He also hopes to identify new types of bacteria that can pass through the gut while carrying the silver particles, allowing them to tackle infections there.

Dr Michael Dempsey, a biologist at Manchester Metropolitan University who has studied the affects of silver nanoparticles on microorganisms, said: "A nanoparticle contains around 15,000 atoms of silver according to some recent research from China on how they work.

"This means a high concentration of silver atoms come into contact with the micro-organism, punch a hole in its wall and destroy it."

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