Illustration of antibodies attacking influenza virus particles
Scientific photo library / Alamy
An antibody cocktail could give us a new weapon to combat seasonal flu and new strains that cause pandemics. The mixture protected the mice from various influenza strains, but has not yet been tested in humans.
Most of the flu treatments and vaccines are based on the body to make proteins called neutralizing antibodies. These bind to specific strains of a virus, preventing it from infecting cells. Such medical interventions can be very effective, but can take several months to develop and can lose their effectiveness if the Mute virus. This is why influenza vaccines are updated in a seasonal way and why researchers work on a universal vaccine that would protect against all influenza stumps or even from all viruses.
Silke Paust at the Farmington, Connecticut Jackson Laboratory, and his colleagues have a different approach. They focus on non -neutralizing antibodies, another type of protein produced by the immune system. Researchers have largely ignored these proteins to combat infectious diseases because they do not precede infection. Instead, they allow the immune system to kill the responsible virus by marking the already infected pulmonary cells.
“We do therapy, not a vaccine. What we are trying to do is creating a drug that you can give prophylactically or therapeutically after an infection to prevent serious illnesses and death, ”explains Paust.
Paust and his colleagues have concentrated on antibodies that would target a viral protein of the flu in a region called M2E, which is essential for the virus to reproduce and is almost unchanged in all the influenza strains.
The researchers conducted a series of experiences in which they tested to what extent the antibodies operated individually or in combination in mice infected with an influenza virus, and found that the combination of three antibodies gave the best results.
They tested the cocktail in mice exposed to two stumps of H1N1 flu, including the one that caused the 2009 swine flu pandemic and gave birth to the H1N1 currently in circulation, and two strains of avian flu: H5N1, which infects fauna in the world and certain animals in the United States.
The researchers discovered that the cocktail reduced the severity of the disease and the amount of viruses in the lungs and improved survival rates in healthy and immunocompromised animals.
For H7N9, for example, all the mice survived when she gave the antibody cocktail during the first three days after the infection, 70% survived if they were treated on the fourth day and 60% if they were treated on the fifth day.
This is the first time that we have seen such a broad protection against flu in living animals, explains Paust. The cocktail also worked when given before infection, so that the drug could potentially be used in advance to prevent the disease.
Even after 24 days of treatment, there was no sign of the mutation of the virus to resist it. “If the virus wants to mutate far from therapy, it should escape the three antibodies because they do not bind exactly the same way,” explains Paust.
“As proof of principle, this shows how an antibody cocktail could be used as a medication to treat people during a flu pandemic that could be used in parallel to vaccines,” said Daniel Davis at Imperial College in London. “But that should be tested in humans before it could be considered a real medical advance.”
The next step, says Paust, is to modify the antibodies that target M2E to make them look like human proteins, so that the immune system does not see them as invaders and attacking them, which has been done before with many antibodies. If it works, safety and efficiency trials would follow.
Paust is considering the cocktail used as a drug stored to combat seasonal flu epidemics. “Ideally, it would be something to give to patients at high risk at the start of the season,” she said. “It would mean that they would not become very sick, essentially.”
Subjects:
