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【科普】英国科学家成功试验出“万能”流感疫
据英国《卫报》报道，由萨拉·吉尔伯特带领的科研团队发现有两种蛋白质存在于所有已知的流感病毒中，并且变异可能性不高。据此，他们针对这两种蛋白质研发出新型疫苗，疫苗所含的T细胞能识别出这两种蛋白质，从而杀死被流感病毒感染的细胞。
“我们已得到了这种疫苗确实有效的证据”，吉尔伯特说，“我们给部分志愿者先接种这种新疫苗，随后又给所有志愿者接种流感病毒。我们发现接种疫苗的志愿者患流感的人数大大少于没有接受疫苗的人”。
传统的流感疫苗作用机理是刺激人体产生病毒抗体以破坏病毒外壁，但病毒外壁极易变异，从而导致疫苗失效。 Flu breakthrough promises a vaccine to kill all strains
A team at Oxford University has had success testing a vaccine that can neuter any strain of flu virus. Photograph: Science Photo Library
Scientists at Oxford University have successfully tested a universal flu vaccine that could work against all known strains of the illness, taking a significant step in the fight against a disease that affects billions of people each year.
The treatment – using a new technique and tested for the first time on humans infected with flu – targets a different part of the flu virus to traditional vaccines, meaning it does not need expensive reformulation every year to match the most prevalent virus that is circulating the world.
Developed by a team led by Dr Sarah Gilbert at Oxford's Jenner Institute, the vaccine targets proteins inside the flu virus that are common across all strains, instead of those that sit on the virus's external coat, which are liable to mutate.
If used widely a universal flu vaccine could prevent pandemics, such as the swine flu outbreaks of recent years, and end the need for a seasonal flu jab.
"The problem with flu is that you've got lots of different strains and they keep changing," said Adrian Hill, director of the Jenner Institute. "Occasionally one comes out of wildfowl or pigs and we're not immune to it. We need new vaccines and we can't make them fast enough."
A universal vaccine would save the time and money now needed to create vaccines to fight whatever particular virus has emerged in any year. The government spent an estimated ?1.2bn in preparing for the swine flu outbreak of last winter.
The process of developing a seasonal vaccine takes at least four months and if the flu strain is highly pathogenic – as in 1918 when millions of people died – the delay means more people get sick and die before the vaccine is ready.
This winter the government was criticised for its handling of the annual winter flu outbreak. Shortages of the seasonal flu vaccine became so acute in some areas that GPs were told to use old stocks of swine flu vaccine instead.
"If we were using the same vaccine year in, year out, it would be more like vaccinating against other diseases like tetanus," said Gilbert. "It would become a routine vaccination that would be manufactured and used all the time at a steady level. We wouldn't have these sudden demands or shortages – all that would stop."
While traditional vaccines prompt the body to create antibodies, Gilbert's vaccine boosts the number of the body's T-cells, another key part of the immune system. These can identify and destroy body cells that have been infected by a virus.
In her trial, Gilbert vaccinated 11 healthy volunteers and then infected them, along with 11 non-vaccinated volunteers, with the Wisconsin strain of the H3N2 influenza A virus, which was first isolated in 2005. She monitored the volunteers' symptoms twice a day, including runny noses, coughs and sore throats, and she calculated how much mucus everyone produced by weighing tissues they used. Though a small study, it was significant in that it was the first vaccine of its type to be tested on people.
Gilbert said: "This is the first time anyone's tested if you can boost somebody's T-cell response to flu and, having done that, if it helps protect against getting flu. It's the first time anybody's done that in people."
Her results showed that the vaccine worked as planned. "Fewer of the people who were vaccinated got flu than the people who weren't vaccinated," said Gilbert. "We did get an indication that the vaccine was protecting people, not only from the numbers of people who got flu but also from looking at their T-cells before we gave them flu. The people we vaccinated had T-cells that were more activated. The people we hadn't vaccinated had T-cells as well but they were in a resting state so they would probably have taken longer to do anything. The volunteers we vaccinated had T-cells that were activated, primed and ready to kill. There were more T-cells in people we vaccinated and they were more activated." Gilbert has now sent her results to a scientific journal.
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作者:admin@医学,生命科学 2011-02-08 01:57
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