The discovery of bat flu has shed light on the evolution of flu A, B and C viruses. It is possible that many of the internal genes of bat influenza viruses are descendants of families of flu viruses that once circulated more widely in previous centuries and that are now extinct – or yet to be discovered.
The bat flu viruses discovered in Central and South America are very different from other flu viruses in humans and animals. All flu A viruses have hemagglutinin (HA) surface proteins, and until the discovery of these viruses, there were only 16 different classes (or “subtypes”) of HA proteins known to exist in nature.