But there is another problem: H7 flu is poor at stimulating immunity. Virologists at the European Flu Summit in Brussels last week told New Scientist that early results show 13 times more H7N9 virus is needed to elicit a protective immune response than is needed for ordinary flu. That’s bad news: the more virus a vaccine requires, the fewer doses that can be grown in a given time.
“H7N9 may be a ‘stealth’ virus that is able to fly under the immune system’s radar,” says Anne De Groot of the University of Rhode Island at Providence. That’s because its surface protein haemagglutinin doesn’t contain many short amino acid sequences – called epitopes – that trigger helper T-cells in the body to stimulate antibody-making cells.
“H7N9 is not very immunogenic, because the epitopes have a very weak signal,” says Masato Tashiro, head of flu at Japan’s National Institute of Infectious Diseases in Tokyo. People differ genetically in the epitopes their T-cells recognise, and his lab has found that Asian people could be especially vulnerable.
See our latest H7N9 publication blog post here – http://www.epivax.com/blog/h7n9_newpub/
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