WOULDN’T IT be great if there was a single vaccine to cover all flu strains? Imagine the potential. One shot could reduce the global need for yearly jabs and possibly even avoid frantic races to design, manufacture and roll out vaccines in the face of pandemic strains such as the H1N1 virus.
Researchers at University College Cork and University of Oxford are collaborating on a new “universal” flu vaccine that targets proteins common to all flu strains. The hope is that this universal vaccine would boost your immune system to quickly identify and destroy cells in your body that are infected with any flu virus.
At present we need to update flu vaccines to protect against emerging strains, because the vaccines target changeable proteins on the outside of a flu virus particle, explains vaccine immunologist Dr Anne Moore of the school of pharmacy at University College Cork. “The problem with seasonal flu vaccines is that they have to be remanufactured every year because you get a lot of changes in the [circulating] virus overall from year to year,” she says.
To predict which flu viruses are likely to be circulating in the coming season, the World Health Organisation monitors prevalent strains and decides which horse to back for a vaccine. Those vaccines teach your immune system to recognise particular proteins on the outside of the virus – HA and NA – and make antibodies to them, so if your body sees the virus for real the immune system will swing into action and destroy the invader.
“Antibodies are very protective against influenza infection, and the antibodies are mostly targeted to the outside proteins, the HA and NA – that’s what the antibodies see,” says Moore.
But if those proteins change on the virus, the vaccine may no longer be effective, hence the need to reinvent vaccines for each new circulating strain.
So the UCC and Oxford team is taking a different approach: to make a universal vaccine that will enable your immune system to recognise proteins within the virus that are conserved across different flu strains.
Their vaccine aims to activate a different arm of the body’s defences, namely T-cells that recognise and kill cells in the body that have already been infected by a virus. People who have been infected with the flu may already have this T-cell “memory”, but a vaccine would bump it up, explains Moore.
Pre-clinical work with the vaccine at UCC has shown encouraging results. “We have seen quite a good protection, and we are just confirming that it is from these specific antigens,” says Moore.
Initial human trials are under way. Early results from a study of 43 people under the age of 50 also look promising, says Dr Sarah Gilbert, reader in vaccinology at Oxford. “We’ve seen a good boosting of immune responses in blood samples taken from volunteers after vaccination,” she says.
So could such a T-cell vaccine replace the seasonal games of cat and mouse? It’s too soon to tell, according to the researchers.
“There is now a renewed interest in developing different types of flu vaccine, and T-cell vaccines will certainly play a part,” says Gilbert. “It’s possible we end up with vaccines that give broad protection being given to the majority of the population every few years, which could greatly reduce the amount of flu that circulates every flu season, plus annual vaccination for those particularly at risk.”
