A UK researcher has developed a new method of protecting birds
against avian flu, that has been shown to be effective against a
range of strains, including H5N1 and the H7N2 strain in the
current outbreak in Lancashire.
As Nigel Dimmock at the
University of Warwick
explains, existing vaccination methods depend on stimulating the
body's immune system, so that white blood cells produce antibodies
that attach to the surface of the virus and start the process of
killing it.
One drawback is that the coat of the flu virus is continually
changing, so vaccination against one strain of flu, for instance
H3N2, is totally ineffective against another, such as H5N1.
However, Prof Dimmock’s new approach developed over the last 20
years overcomes this by using an entirely new method, that uses a
'protecting virus'. This virus contains genetic material that has
been altered, rendering the virus harmless and unable to spread
like a normal flu virus.
If it is joined in the cell by another influenza virus, it
starts to reproduce at a much faster rate than the new influenza
virus. This fast reproduction rate - spurred by the new flu
infection - means that the new invading influenza is effectively
crowded out by the 'protecting virus'.
Prof Dimmock explains that this slows the progress of the new
infection, prevents flu symptoms and gives the body time to develop
an immune response to the harmful new invader.
"In effect the protecting virus converts the virulent virus into
a harmless live vaccine."
Trials show that this virus gives the samebeneficial effect for all
strains.
“This is particularly valuable as a preventative measure as you
don’t need to know the exact make up of the new strain before
deploying the protecting virus
In addition it protects instantly, whereas protection generated
by conventional flu vaccination takes 2-3 weeks to become fully
effective.
He sees the 'protecting virus' having a useful role in poultry,
as it is possible to deliver it in the bird's drinking water. One
dose should protect a chicken for weeks.
The Warwick research team has now filed a patent for
the 'protecting virus' and are looking to carry out further
trials.