An engineered influenza virus, under development in Britain, could overcome the problems of conventional vaccines and protect humans and animals.

Credit: CDC

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LONDON: An engineered flu virus that outcompetes harmful strains could become our newest tool in the fight against global pandemics.

Existing vaccination methods depend on stimulating the body's immune system to produce antibodies that attach to the surface of the virus and start the process of killing it. This works well for many diseases such as smallpox, polio and measles, but is much less effective with influenza because the coat of the flu virus is continually changing.

The changing nature of the flu virus means that vaccination against one strain of flu is ineffective against another. This is especially problematic when a new pandemic strain emerges, because all existing vaccines are likely to be ineffective.

The new method of protection, under development by a team at the University of Warwick led by Nigel Dimmock, uses a "protecting virus" to fight the disease. The protecting virus contains a major alteration to one of the virus's genes that coverts harmful infections into a vaccine against those forms of influenza.

The genetic material of a flu virus consists of eight individual segments of single-stranded RNA (ribonucleic acid). Dimmock's protecting influenza virus has a specific deletion of about 80 per cent of the RNA of one of these eight strands.

This deletion makes the virus harmless and prevents it from reproducing by itself within a cell, so that it cannot spread as a normal influenza virus can. However, if it is joined in the cell by another flu virus, it retains its harmless nature but starts to reproduce - and 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 crowded out by the protecting virus. This vastly 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.

The team's findings suggest that the protecting virus would have the same beneficial effect whatever strain of influenza is infecting a person. This is because the coat of the virus is irrelevant to the protection process - the effect works on the virus genes inside the cell. Additionally, the technique has been shown to work on animals, and could offer protection against the full range of influenza A infections, including H5N1 (bird flu) and any new pandemic or epidemic strains that emerge.

According to the researchers, the protecting virus provides instant protection, as opposed to the two to three week lag before traditional flu vaccines become effective. It can also counter an actual infection and offer protection if given up to 24 hours after first infection, and possibly later.

The research has been deemed to be so important that it has been publicised despite the fact that the work has not been fully published.

A statement issued by the university said: "In normal circumstances the university would not attempt to publicise research that has not been fully published … However, given the current heightened global concern about the risks of influenza outbreaks, the university thought it was important to alert people to this research at the earliest opportunity to enable the researchers to find support to allow early human trials and bird testing."