Molecular virologist and principal investigator Mathilde Richard (see picture) calls the publication a "major milestone" in research that has taken more than ten years. This is partly due to the highly complex technique used, known as antigen mapping. The research group created a digital three-dimensional model to map all known avian influenza variants, also known as H5. "There was no global overview of which mutations the virus had undergone over the years," says Richard. "With this model, we can see exactly how all existing variants differ from each other."Solar System
The result is a digital model that resembles a solar system, with a center surrounded by variants of the virus. The further apart the variants are, the more mutations have occurred and therefore the less related they are. "This led us to the idea of designing a vaccine that targets the center of that solar system. If you give that vaccine to an animal that later becomes infected with one of the variants located at the very edge of the model, it also appears to protect against that variant," says Richard.The ferrets in the study received the "universal" vaccine and were then exposed to two very different subtypes of the avian influenza virus. The vaccine induced an immune response in the animals to almost all the variants in the model. The ferrets did not become ill, and the vaccine prevented the virus from replicating outside the respiratory tract.
According to experts, the avian influenza virus is a real candidate for a new pandemic. The virus has not yet spread to humans on a large scale, but it has been mutating for about thirty years to the point that various mammals are becoming increasingly susceptible to illness and even death from the virus. Infections were long limited to poultry, but the virus has now been identified in animals including foxes, grizzly bears, seals, and, for the past two years, in dairy cows in the United States.
If pigs contract both avian and human flu simultaneously, a variant can emerge that causes a pandemic for humans. This happened in 2009 with swine flu, which originated in pigs.
48 different vaccines
People cannot (yet) transmit the virus to each other, but animals can make people sick. Since 2003, nearly 1,000 people worldwide have been infected with avian flu, half of whom have died. According to experts, this is just the tip of the iceberg, as only seriously ill people report the virus. The extent to which the virus jumps from animals to humans is therefore not entirely clear, and that is precisely what worries virologists and epidemiologists. The virus only needs a few mutations to become pandemic in humans, and some of those mutations have already been identified.Therefore, effective vaccines are being sought worldwide. "If a new variant breaks out somewhere in the world, a new candidate vaccine is always being developed for it," says Richard. This is why the World Health Organization (WHO) has currently registered 48 different candidate vaccines. "But by the time such a vaccine is finished and rolled out worldwide, the virus has often mutated further. This strategy is therefore not sustainable in the long term. Moreover, you never know for sure which variant will ultimately cause a pandemic. A vaccine specifically targeted at one variant will not work for another. Our 'universal' vaccine may be an answer to that."
'New' variant already 10 years old
Why didn't scientists think of this sooner? According to Richard, the 3D model the researchers created, together with scientists from the University of Cambridge, sheds new light on how the bird flu virus evolves. "For a long time, we thought that the variants that would emerge after mutation would become increasingly distant from each other, and therefore less and less similar, like a solar system that continues to expand," says Richard. "But that turned out not to be the case. In our model, you see that from 2010 onwards, space doesn't expand much: sometimes we see 'new' variants emerge, resembling the variants that were already very common ten years ago.
See also:
Article in Nature
Article in Amazing Erasmus
Interview for NRC newspaper
Interview for Nature Podcast
