Using viruses to beat superbugs

AmpliPhi Biosciences says bacteriophages should be revisited as antibacterial agents

Viruses that can target and destroy bacteria have the potential to be an effective strategy for tackling hard-to-treat bacterial infections, according to a scientist at antibacterial specialist AmpliPhi Biosciences.

Dr David Harper, chief scientific officer at the UK division of the firm, based in Shambrook, Bedfordshire, says the development of such novel therapies is being accelerated in response to growing antibiotic resistance.

The injection needle on the bacteriophage penetrates its bacterial target
Source: AmpliPhi Biosciences

Bacteriophages - viruses that can infect bacteria and multiply within them, breaking down the cell and destroying the bacteria - are found everywhere including in river water, soil, sewage and on the human body. Soon after their discovery in 1915, bacteriophages were investigated as antibacterial therapeutic agents. A limited understanding of their mode of action meant early work was often unsuccessful and with the advent chemical antibiotics, bacteriophages were passed over as therapeutics.

Dr Harper explains why bacteriophages are being revisited as antibacterial agents. ‘Each bacteriophage is highly specific to a certain type of bacteria and needs the right bacterial host cell in order to multiply. The more bacterial targets there are, the quicker they grow by killing the host cells. Therefore it seems very likely that infections harbouring high numbers of bacteria will benefit most from bacteriophage therapy - for example chronically infected ears, lungs and wounds,’ he says.

‘For these types of infection, only a tiny dose of the virus is needed - as small as one thousandth of a millionth of a gram. This can usually be administered directly to the site of infection in a spray, drops or a cream. The major advantage of bacteriophages is that they don’t infect human cells so seem likely to be very safe to use.’

Increasing resistance to antibiotics has meant that bacterial infections are becoming more difficult to treat. And with fewer antibiotics available to treat drug-resistant infections, research into bacteriophage therapy has been accelerated.

‘The rate of new antibiotics coming onto the market does not match the rate of increasing drug-resistance. The need for new approaches to counter such high resistance is both urgent and vital. New approaches will save lives,’ said Dr Harper.

AmpliPhi Biosciences conducted the first clinical trial for safety for bacteriophage therapy in 2005 and the results demonstrating its effectiveness were published in 2009.

The company is planning further clinical trials in conditions where existing antibacterial therapies are not able to help.

‘With the results of further clinical trials, once regulatory issues are overcome and future invest-ment secured in this area of research, this should lead to the development of novel products suitable for widespread use to tackle bacterial diseases and overcome antibiotic resistance,’ says Dr Harper.

Dr Harper will be speaking on this subject at the Society for General Microbiology’s Spring Conference in Dublin this week. Full programme details are available at www.sgmdublin2012.org.uk

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