Scientists are mixing up a vaccine cocktail that can possibly target all strains of the influenza virus and protect against future problems caused by the complex disease.

Seasonal influenza causes high rates of illness and mortality. Every year, researchers try to change the vaccine to ensure that it matches current viruses that are circulating, such as H1N1. Instead of having to change the vaccine from time to time, experts from the National Institute of Allergy and Infectious Diseases (NIAID) have strategized a way to incorporate a number of influenza viruses into one vaccine.

The study, which is led by Jeffery Taubenberger, MD, Ph.D., looked at H1, H3, H5 and H7. Out of the 16 most common H proteins, these make it to the top four. The team mixed together non-infectious virus-like particles, or VLPs, that contain these four H proteins. H1 and H3 are most common in humans, with outbreaks occurring since 1918. The potentially pandemic H5 and H7 are also known to infect humans, but the strains come from outbreaks among birds.

The VLPs were tested on mice.

In the experiment, the researchers at NIAID injected the VLP cocktail into the mice, then induced them with several doses of a number of influenza viruses, including H proteins not present in the VLP cocktail. The researchers saw that the vaccinated mice were significantly protected against influenza.

Out of 30 vaccinated mice that were exposed to the 1,957 H2, avian H10 or H11 viruses, 30 survived.

Out of 24 vaccinated mice that were exposed to H6, 20 survived. These 20 also lost less weight than unvaccinated mice. All the unvaccinated mice that were exposed to influenza died.

Significant protection was also found against avian H5N1 and H7N9 viruses, which are known to have recently caused a number of cases and deaths in humans.

In additional tests, the researchers also found that the vaccine worked for at least six months and was even effective in older mice.

According to Taubenberger, if the vaccine is even a tiny bit different from the target, not much protection should be expected. The VLP cocktail was designed in a way that won't make people worry so much about matching the vaccine antigen to the influenza virus.

The study, which is explained in more detail and published in the online journal American Society for Microbiology, has only come up with its initial findings but poses practical strategies for devising a universal flu vaccine that can promise broad protection. 

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