New Approach to Creating Flu Vaccines Can Help Make Them Universal

Every year health workers introduce new flu vaccines designed to protect people against a particular set of strains that is expected to rage this season. However, such guesswork is not always fruitful, and the response of the immune system can prove to be insufficient. Now researchers have rolled out a new solution which can help solve this issue.

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How do standard vaccines work?

A team from the University of California collaborated with their Chinese colleagues to develop a new vaccine that works in an unusual way.

Most common vaccines introduced annually contain several virus strains which, according to researchers, are more likely to attack citizens this season. The viruses used a usually killed, so they cannot make you sick. There is a downside too: the response of the immune system is not as strong as it might be if it was a live “wild” virus.

When the liquid with the dead viruses gets into your bloodstream, the antibodies protecting you “recognize” the flu and help neutralize it. However, the immune system’s reaction to the dead virus is only partial: there is no strong T cell reaction that could fend off the intruders effectively.

How does the novel vaccine work?

The special thing about the newly developed vaccine is that it uses a genetically modified virus that is not dead: the live virus evokes a very strong response, while not making the one who gets the shot sick. Theoretically, such an approach can come as a revolution in flu shots, because if it proves to work in humans, then it will help the body much better than common vaccines.

The thing is, the T cell response triggered by the live virus has two advantages over the way standard vaccines work: first, the immune system’s response lasts longer if the virus is not dead, and, second, it can help defend the body from several strains. The reason behind it is that antibodies recognize intruders which look familiar by their shape, whereas T cells use several criteria to distinguish whether it’s an enemy they have encountered. It’s like an extra line of defense that the flu will have to face after it evades the antibodies.

Why is the modified virus special?

To create a virus that would both be able to trigger a strong response and not cause an illness at the same time, the investigators looked at what mutations make the virus susceptible to interferon. Then they designed a virus of their own which had several mutations that make it an easy target for the immune system. Still, despite being more of a dummy, this virus triggers a reaction strong enough to make the T cells be on the alert and provide antibodies for quite a long time.

The vaccine proved to be effective when injected into mice and ferrets. It’s not known yet whether it can work in humans. However, even if it does, there are several obstacles which mean rolling out the new vaccine and making it available to anyone right now is not a good idea.

Researchers say that although the study showed the vaccine provides cross-protection across two flu subtypes, it does not necessarily mean that the vaccine is universal. Besides, the strong immune response can have adverse effects, such as destruction of lung tissues. If a person has H5N1, such a state of the immune system can even be deadly. That is why more research is needed until the vaccine can be tested in humans. Nevertheless, the innovative approach is considered a breakthrough by a number of scientists. Should the vaccine really be polished to become safe enough, annual flu shots will not be needed any more.

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