Scientists have engineered a viral vector to convert cells lining the airways into producers of antibodies against flu.
Squirting a dose of the modified agent into the noses of mice and ferrets fully protected the animals against what would otherwise be a lethal dose of the disease.
University of Pennsylvania scientist Maria Limberis and her colleagues made the protective agent by inserting the gene coding for an antibody that can neutralise a broad range of influenza strains into a virus vector called AAV9 (adeno associated virus 9).
Between 100-1000 billion particles of this virus, which had also been modified to prevent it from growing, were then introduced, in a droplet of saline, into the nostrils of test mice and ferrets. There, the AAV9 vector entered the cells lining the animals' airways carrying with it the gene encoding the recipe for making anti-influenza antibodies, which the the airway cells then began to secrete onto their surfaces.
When the animals were then subsequently challenged with a dose of flu, even as few as 3 days after the protective virus treatment, all of them remained well. Control animals on the other hand, which were given an AAV9 vector encoding an irrelevant non-flu targeted antibody, all rapidly succumbed to flu infection. Encouragingly, the therapeutic AAV9 vector resulted in sustained production of the protective influenza-neutralising antibodies in the airway cells for at least 100 days, and if needed the AAV9 vector treatment can be re-administered.
According to Limberis, "a major benefit of this approach is that we can rapidly produce protective antibodies, even in people whose immune systems don't work so well, like the elderly." The technique also has the advantage of rapid scalability. "When the next pandemic comes, you could have therapeutic doses of this ready to go in a fraction of the time it took to make the jab for swine flu."