A new spray that helps boost the immune system can fight off flu in just two hours - even before symptoms have developed, according to scientists.
The drug, delivered by a nasal spray, contains a synthetic protein that triggers the immune system to fight the flu before the body normally would.
Once a person is exposed to the flu, current treatments are designed to target the current circulating strain exactly, but the virus can sometimes develop a resistance against them.
Super spray: A new drug, delivered through a nasal spray, can fight off flu in just two hours (posed by model)
This new treatment doesn't need to match the virus exactly and gets the immune system to react almost immediately to the threat before the body normally would.
Flu is potentially fatal to people with a low immune system as they struggle to shake off the infection and can also be lethal to the elderly.
Researchers at San Diego State University in America focused the study on the protein EP67, which has previously been used as something added to a vaccine to help activate the immune response, but they wanted to see if it would work on its own.
They tested EP67 on mice by infecting them with a flu virus - finding those given a dose within 24 hours did not get sick, or as sick, as those not treated with the protein.
The level of illness in mice is measured by weight loss - typically mice lose about 20 per cent of their weight when infected with the flu, but those treated with EP67 lost an average of six per cent.
New cure: Researchers at San Diego State University tested the drug on mice infected with flu and found they did not get sick
The researchers also found mice who were treated a day after being infected with a lethal dose of influenza did not die.
EP67 is active in animals, including birds, so the finding could also have huge implications for veterinary applications.
It could also be used if there is a new strain of the infectious disease, before the actual pathogen has been identified, like in SARS or the 2009 H1N1 influenza outbreak.
Future research will examine the effect EP67 has in the presence of a number of other pathogens and look closer at exactly how EP67 functions within different cells in the body.
Although this study, published in science journal PLoS ONE, focuses on the flu, EP67 has the potential to work on other respiratory diseases and fungal infections and could have huge potential for emergency therapeutics.
Professor Joy Phillips, of San Diego State University, said: 'The flu virus is very sneaky and actively keeps the immune system from detecting it for a few days until you are getting symptoms.
'Our research showed that by introducing EP67 into the body within 24 hours of exposure to the flu virus caused the immune system to react almost immediately to the threat, well before your body normally would.
'When you find out you've been exposed to the flu, the only treatments available now target the virus directly but they are not reliable and often the virus develops a resistance against them.
'EP67 could potentially be a therapeutic that someone would take when they know they've been exposed that would help the body fight off the virus before you get sick.'
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