A molecule the body produces naturally in response to virus infection could be a viable flu treatment in the future, suggest researchers at the Francis Crick Institute in London.
Their study in mice has found that the antiviral, called interferon lambda (IFNλ), can control flu infection without sparking further inflammation.
A team led by Dr Andreas Wack at the Crick tested IFNλ and a second interferon called alpha (IFNα) in mice to explore their potential as therapies for the influenza A virus. They worked with colleagues from Aarhus University in Denmark and the respiratory therapy team at GSK in the UK and the results were recently published in EMBO Molecular Medicine.
There are between three and five million cases of severe illness caused by influenza virus each year around the world, and up to 500,000 deaths. Influenza A is also capable of causing devastating pandemics.
The researchers used a mouse model that responds to flu in a similar way to humans to investigate whether either interferon could stimulate an antiviral response that helped fight flu infection.
They found that IFNα reduced viral load but made disease symptoms worse because it increased inflammation and tissue damage in the lung.
In comparison, mice treated with IFNλ when flu symptoms set in recovered better and showed increased survival over mice given no treatment or IFNα. This is because the negative side effects seen in mice treated with IFNα were absent. 80% of mice survived when given IFNλ compared with 50% of untreated mice and 20% of mice given IFNα.
The scientists tested the effect of IFNλ on human cells in the lab and found the same response patterns as in mouse cells. The next step is to test the therapy in people who have flu.
Dr Wack is optimistic: "We know IFNλ has a decent safety profile as it has already been tested for safety in humans. It passed phase 1 and 2 clinical trials as a hepatitis C therapy before better treatment options were found for that disease. If it were to be considered as an influenza treatment, this means the starting point to test it would be relatively advanced."
The team hope IFNλ's existing safety profile means that if a new pandemic influenza strain hit the population in the near future, IFNλ might be considered as a treatment option. The team suggest that IFNλ may also be useful to treat other families of viruses that cause respiratory disease.
Dr Wack's research group will move into the new Crick Laboratory in the coming weeks from the Crick's Mill Hill Laboratory. It was in Mill Hill in 1957, when it was the National Institute for Medical Research (NIMR), that interferons were first identified by Dr Alick Isaacs and Dr Jean Lindenmann. NIMR became part of the Francis Crick Institute in 2015 along with Cancer Research UK's London Research Institute.
The interferon study received core support from the Francis Crick Institute and funding from the Medical Research Council, the Danish Council for Independent Research and a Biotechnology and Biological Sciences Research Council-GSK funded studentship.
Original research paper
Sophia Davidson et al., IFNλ is a potent anti-influenza therapeutic without the inflammatory side effects of IFNα treatment, EMBO Molecular Medicine