A universal 'flu vaccine capable of protecting people against multiple strains of the virus has come a step closer.
Influenza causes millions of cases of severe illness globally each year. And because the virus regularly alters its appearance and circulates as a range of different strains, vaccines employed to prevent it must contain a cocktail of at least three different deactivated viruses. The strains used are selected on a "best-guess" basis, where researchers attempt to predict which viruses will become the dominant circulating types that year and vaccines are then updated to reflect this. An incorrect call, though, can render a vaccine useless.
Now scientists may have found a way to solve the problem with the discovery of an unchanging part of the virus coat that is common to many different strains of the agent. Antibodies targeting this region, Scripps scientist Damien Ekiert and his colleagues have found, can neutralise multiple virus strains, including even strains separated by 50 years of virus evolution.
The team made the discovery, which is published in the journal Science, by collecting antibodies from patients recently vaccinated against one strain of 'flu and then looking to see if any of them were also capable of neutralising other 'flu strains. One of the antibody clones they uncovered, termed CR8020, recognised a range of so-called "group 2" 'flu strains, including those designated H3, H7 and H10.
This promiscuous blocking ability occurs because the antibody binds onto a critical region of the 'flu particle, preventing the virus from uncoating itself inside an infected cell. And because this target region remains unchanged across generations of viruses, the antibody works across a wide range of virus strains.
The team also recently uncovered a similar antibody, called CR6261, which neutralises the rest of the 'flu family members not covered by CR8020. Both antibodies can protect mice exposed to potentially lethal doses of 'flu virus. This suggests that a vaccine engineered to drive the production in the body of both types of antibody could provide a universal vaccine capable of protecting against all strains of influenza.