A “universal” flu vaccine has taken a significant stride towards reality after two jabs were shown to protect animals against several different strains of the virus.
Flu, which kills about 8,000 people in the UK each year, is a difficult disease to vaccinate against because the strains vary so much from year to year. In some winters, such as the last one, this can lead governments to stockpile large numbers of jabs that prove ineffectual against the particular strain that happens to dominate that season.
Several teams of scientists around the world, including one at King’s College London, are now trying to target the proteins that do not change from virus to virus in order to create a vaccine that works against the majority of human strains of influenza, as well as some that can cross over from animals, such as bird flu.
One of the most promising approaches is to use the “stem” of the flu virus, where its distinctive proteins, known as haemagglutinins [HA], differ much less between seasonal strains.
Researchers at the Scripps Research Institute [TSRI] in California and Janssen Pharmaceuticals, a large international drugs company, made an artificial and harmless version of this stem that can theoretically arm the body’s immune system against most kinds of flu.
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Writing in Science, they showed that their vaccine protected mice and cynomolgus monkeys against several different strains.
Ian Wilson, professor of structural biology at TSRI, said the results showed his team was “moving in the right direction for a universal flu vaccine”. “If the body can make an immune response agains the HA stem, it’s difficult for the virus to escape,” he said.
Another group of academics centred around the US National Institutes of Health [NIH] used a similar tactic — but this time creating a self-assembling complex of the proteins — to successfully immunise mice and ferrets. Their findings were published yesterday in the journal Nature Medicine.
Sarah Gilbert, professor of vaccinology at the University of Oxford, said the two sets of results marked “significant advances” but it would be some time before either was shown to be safe in humans.
“We’ve known for some time that there is a region of HA, the stem, that does not change and is present on all flu A viruses, and if we can use only that part in the vaccine we could raise immunity to many different viruses at the same time, but it has been technically challenging to make a vaccine that works in that way,” she said.
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“Now two groups have made significant advances, each of them producing HA stem vaccines that work well when tested in animals. This is an exciting development, but the new vaccines now need to be tested in clinical trials to see how well they work in humans.
“This will be the next stage of research, which will take several years. So we are still some way from having better flu vaccines for humans.”
Barney Graham, deputy director of the vaccine research centre at the NIH, said his group were not yet sure whether they would move directly to testing their vaccine in humans or tinker with its structure to make it more effective at neutralising some strains of the virus.
“We are still considering whether to take this construct into clinical evaluation or make additional refinements to improve the elicitation of cross-reactive neutralising antibodies as well as cross-reactive binding antibodies,” he said.