This antibody cocktail protects against all types of flu viruses

A universal cocktail to treat the flu. A US team claims to have developed an antibody therapy that has been shown, in mice, to combat all influenza strains tested, including the avian and swine variants that pose a pandemic threat.

According to its authors, a team from the Jackson Laboratory , this therapy could change the way influenza, one of the most deadly infectious diseases, is treated.

Unlike currently approved flu treatments, which target viral enzymes and can quickly become ineffective as the virus mutates, this therapy did not allow viral evasion, even after a month of repeated exposure in animals.

This difference could be crucial in future outbreaks, where survival often depends on how quickly and effectively doctors can implement treatments, and vaccine development will take about six months.

" This is the first time we've observed such broad and long-lasting protection against influenza in a living system ," notes Silke Paust, senior author of the study. "Even when the therapy was administered days after infection, most of the treated mice survived."

These findings challenge the long-held idea that for antibodies to be useful as therapy against viruses, they must be " neutralizing " antibodies that bind directly to viruses and prevent them from infecting cells.

Instead, the team designed "non-neutralizing" antibodies, which don't prevent infection but instead target infected lung cells and recruit the immune system to clear the infection. This new approach could transform the way scientists design treatments for other viruses.

"Most of the antibodies our bodies produce are non-neutralizing, but medicine has largely ignored them," Paust explains. "We showed they can save lives. Even with lethal strains like H5 and H7 avian flu , this therapy saved lives long after the infection had set in."

The team developed a therapy targeting the M2e region of the influenza A virus' matrix protein 2, which is highly conserved across all strains. The combination of three antibodies prevented the development of viral resistance, even after repeated exposures, and sequencing confirmed the absence of mutations in the M2 region after 24 days of treatment.

"The virus didn't mutate even when using individual antibodies," Paust notes. "But in a flu season with millions of people taking this therapy, I'm much more confident that we can prevent therapy escape if we use the cocktail."

Furthermore, the study showed that the antibodies were effective at low doses, both before and after influenza infection. The cocktail significantly reduced disease severity and pulmonary viral load, and improved survival rates in both healthy and immunosuppressed mice.

In testing H7N9, a type of avian flu that can be fatal to both animals and people, the team found that a single dose of the treatment reduced the amount of virus in the lungs, even when given four days after infection. The reduction in viral load correlated with improved survival rates . All mice treated with the antibody cocktail survived for the first three days after infection, while 70% and 60% survived on days four and five, respectively.

Although the results are preliminary, they hold promise for a future in which patients could have access to stockpiled therapies for rapid implementation in the fight against seasonal outbreaks or pandemics. Currently, flu vaccines are updated seasonally because the virus continually mutates, rendering immunity to previous strains irrelevant.

The team is now working on designing antibodies for clinical trials. The idea is to create a "humanized" antibody with the same specificity to target the M2 protein, but without triggering an immune response against the therapy itself or diminishing its effectiveness in humans.