On March 31, the European Research Council announced the lucky recipients of the most popular (because the most significant) research grants from the Old Continent: 185 projects, among which the agency distinguished some flagship projects. At the top of the list is not a large international initiative in atomic physics or a promising development in neuroscience, but the initiative led by Martin Schwemmle and his team at the Institute of Virology at the University of Freiburg, Germany, on a new form of influenza discovered in bats. Obviously, the Covid-19 epidemic and its connection to bats is not without reason. But even outside this context, this work illustrates both the uniqueness of these animals and the potential that can be drawn from them.
For a long time, influenza viruses seemed to sulk bats. Reputedly born in sea ducks, these pathogens had diversified to invade many species of birds and mammals. But the bats, despite their great acquaintance with these naughty little visitors, seemed to escape it. In 2012, however, a first influenza A virus was discovered in a Guatemalan bat, and the following year a second one, on another Peruvian species.
Two new families, in truth. Listed according to the protein used to recognize the cell to be infected (H) and the mode of entry into said cell (N), the viruses already offered a vast repertoire, ranging from the famous H1N1 to the most confidential H16N9. H17N10 and H18N11 were therefore born.
Offspring of a completely different kind. While all flu viruses cling to sugars in lung cells, bat viruses target receptors called MHCclass2 found on different cells of the immune system. For the bats, these strangers do not seem to pose any problem. But what about other animals?
Future displays of infectious episodes
Martin Schwemmle’s team has shown that these viruses can infect ferrets and mice. When injected into the nasal passages, the virus infected and developed in the epithelial cells. But he did not go down into the respiratory system and caused no symptoms in his new hosts. However, it has failed to infect the birds. For the German biologist, the risk of seeing these new viruses touch humans and trigger a zoonosis is “Very unlikely … but not zero”. The flexibility and variety of influenza viruses that these discoveries highlight, however, suggest serious surprises from our future winter visitors.
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