A Japanese media source reported at the end of last week that a team of researchers working under Japan’s Health, Labor and Welfare Ministry has developed a new universal flu vaccine that will work against many types of influenza virus, and describes the breakthrough as a potential “silver bullet” against new strains.

According to a 30 January report in Yomiuri Shimbun, one of the big five newspapers in Japan, clinical use of the experimental flu vaccine in humans is still years away, but trials in mice have shown promising results, even on flu strains that mutate rapidly.

The daily newspaper reported that the new vaccine was the result of collaboration among scientists from Japan’s National Institute of Infectious Diseases, Hokkaido University, Saitama Medical University and the chemical company NOF Corp.

Flu vaccines rely on developing new proteins that coat the surface of invading viruses like “barbs” that are then recognized by the immune system of a vaccinated person. The immune system detects the proteins and attacks the whole mass, including the underlying virus.

But conventional vaccines rely on developing new proteins in line with new mutations of the virus. As the virus mutates, the proteins developed for the previous vaccine don’t match the new viruses when they invade the body and so the antibodies generated from the previous inoculation don’t recognize and attack them.

That’s why new vaccines have to be developed every year. Worldwide experts gather at the end of every flu season and try to predict which strains are likely to give rise to new strains in the next season. These are modelled on computers and give information for vaccine development, usually two or three strains are used to make the new vaccines.

But the information has to be decided well in advance of the flu season to give the manufacturers time to make enough batches to inoculate the population. This “lead time” is sometimes long enough for the virus strains to develop in an unpredicted direction and the vaccine for that year doesn’t exactly match the strains that actually circulates in the next season, but it is still close enough to make it worth having the flu shot because they offer some protection.

So what’s different about this new research breakthrough? The difference is, unlike the current vaccine technology, this new method targets the proteins inside the virus, not the ones on the outside. The proteins inside the virus don’t change as fast as the ones on the outside. Even if the virus mutates, the internal proteins on the new strain are very similar to the ones in the old strain, unlike the coating protein which may change to a completely different shape of “barb”.

The experimental vaccine that the researchers on this project are working on uses an artificial version of a protein developed by the team. It is attached to a special lipid membrane and when the vaccine is injected into the organism the immune system attacks the cells infected by the virus.

For this experimental vaccine the researchers used internal proteins from three common influenza strains: the Hong Kong A strain, the Soviet A type, and the highly pathogenic H5N1 bird flu strain, which many experts predict will one day mutate into a form that passes easily from human to human.

To test the vaccine, the researchers vaccinated mice that had been injected with human genes that boost immunity and then infected them with the three virus strains. The mice showed no symptoms of illness and the vaccine stopped the viruses from multiplying.

The next stage is to investigate the safety of the vaccine in humans, said the report in Yomiuri Shimbun.

Tetsuya Uchida, a senior researcher at the National Institute of Infectious Diseases and a member of the vaccine development team told the paper:

“We’ll investigate what dosage will be safe and effective for humans. I hope the vaccine can be put to practical use as soon as possible.”

A UK team of researchers based at Oxford University is also developing a similar type of flu virus, reported the paper.

Click here for the National Institute of Infectious Diseases in Japan.

Sources: Yomiuri Shimbun.

Written by: Catharine Paddock, PhD