Each fall, millions of people roll up their sleeves for a vaccine against the flu, hoping to give their immune system a leg on influenza. But flu viruses are thousands of strains that mutate and evolve with the seasons, and the vaccine can not protect against all. Now, two groups of researchers have independently created vaccines that provide the basis for a long-sought shot that could protect against all types of flu.
"This is really cutting-edge technology," said Antonio Lanzavecchia, an immunologist at the Federal Technology Institute in Zurich Switzerland, which is affiliated to two studies. "There is still work to do, but this is a step forward and it is heading in the right direction. "
scientists are developing vaccines against influenza by predicting the most likely strains infecting a population. They use monitoring flu the year as well as field reports from the countries of the southern hemisphere to guess which strains are most likely to hit North America at the height of the flu season, December to March. But viral conjecture is a tricky business, and it is impossible to be 100%. This uncertainty makes the uneven protection, and that flu strains mutate during the season, vaccines are becoming less and less effective.
influenza vaccines stimulate the production of antibodies against pieces of dead virus. If the return of the virus, antibodies can recognize, attack and neutralize the threat. But because these vaccines are based on parts of the virus that evolve during a flu season, the protection is not guaranteed.
To solve this problem, two research teams independently focused on a protein called hemagglutinin, found on the surface of the H1N1 influenza virus. It has two main components: the head of the part of the virus that mutates and changes of the strain to strain and the rod, which is similar in most strains of influenza. The teams tried to remove the variable region of the head and hold the rod as a basis for vaccines. But hemagglutinin appears to be quite low. Once decapitated, the rod falls apart, and antibodies can not bind to it.
To anchor the stem headless, teams had different approaches. Researchers writing today Nature Medicine used a two-step method: They introduced a combination of mutations to stabilize the core of the hemagglutinin stem. Then they delimit a nanoparticle derived bacteria of the rod, which has reached the subunits of the protein as well as to hold it in the correct position. The other team, wrote today in Science applied a combination of mutations that realigned the subunits of the stem at the top. This was enough to sustain a functional structure for the vaccine.
When vaccinated mice teams, both groups saw a complete protection against the H5N1 virus, a deadly flu strain distantly related H1N1. In both studies, mice that did not receive the vaccine strains derived died, but the vaccinated mice all survived. In other experiments, anchoring the nanoparticle vaccine have shown partial protection in ferrets, while the other vaccine showed partial protection in monkeys. Two of six ferrets vaccinated became ill and died, compared to a death rate of 100% for unvaccinated ferrets. None of the monkeys died, but those who were vaccinated were significantly lower than their unvaccinated mates fevers.
"The [experimental] designs were different, but the end results were very similar and highly complementary," said Ian Wilson, co-author on the science paper and a structural biologist and computer at the Scripps research Institute in San Diego, Calif. "it is a promising first step, and it is very exciting to see this research to fruition." The authors of both studies say the next step is expanding the protection to other flu strains, namely H3 and H7.
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