Have you ever wondered why you need to get an influenza vaccination each year to protect yourself? Or even why it seems like another pandemic threat is announced before every flu season?
Well, it’s all to do with the evolution and genetic plasticity of the influenza virus. This is what makes it so difficult to make a good vaccine match for those viruses currently in circulation.
And it makes it even more difficult to make a vaccine for those viruses that might infect us in the future.
The holy grail
Researchers have been trying for decades to find the “holy grail” of a universal influenza vaccine.
It would protect us against all types of influenza viruses – preferably after only a couple of doses – just like the other vaccines most of us were given as children.
Progress in this endeavour has been described last week in an article in the prestigious journal Science.
A collaboration of scientists working in Switzerland and the United Kingdom have discovered an antibody (small proteins present in our blood that usually identify and neutralise bacteria and viruses) that binds to all influenza A viruses (there are 16 different subtypes) that they tested.
This is unusual as antibodies generally only bind to a few different subtypes of influenza, leaving us susceptible to infection with other subtypes.
It’s what happens when we are naturally infected with influenza or when we get vaccinated against it.
It’s also the reason why pandemic influenza (caused by influenza A viruses) is an ever-present danger – previously raised antibodies don’t react with new influenza viruses that may come from birds or pigs.
The new work builds on previous findings, such as Okuno et al. 1993, Wang et al. 2010 and Ekiert et al. 2011, who found similar antibodies which were capable of binding to certain subgroups of influenza A viruses.
Using modern recombinant DNA techniques and expression systems, these antibodies were synthesised in the laboratory and given to animals either before or after they were infected with influenza viruses.
Both this group and the previous groups were able to show high levels of protection in mice given these special antibodies.
Before and up to three days following infection, these antibodies were capable of saving the mice from what would otherwise have been a lethal infection.
The experiments open the possibility of using one or more antibodies in the treatment of influenza either before or probably more commonly after infection occurs.
Why bother?
To some, this type of treatment for influenza may sound a little extreme but there are a number of serious cases of seasonal influenza each year.
And during the 2009 influenza pandemic there were a large number of admissions to intensive care units and 191 deaths in Australia alone.
Having a highly potent antibody that could be infused into very ill patients might help control severe influenza A infections.
It would be especially welcome in countries that have cases of the deadly human A(H5) influenza commonly known as “bird flu,” for which antiviral drugs have only had limited success.
Of course, the real aim of these studies is to make a totally new influenza vaccine. Instead of relying, as we do currently, on using a crude “killed” virus-based vaccine that is grown in eggs, this discovery opens up the possibility of making a synthetic vaccine on a large scale at a relatively low cost.
Much work needs to be done to translate these latest observations into practice. But preliminary results from work done in mice with a peptide (a very small, simple protein) based on a similar region of the virus protein by Wang et al. 2010, has generated broadly protective responses in mice to divergent subtypes of influenza A.
So, with some luck, hard work and around five to ten years, we may have our universal vaccine for influenza A.
Then all we would need is another for influenza B viruses, which also infect people but usually cause less morbidity and mortality, and don’t cause pandemics.