In organisms that have extreme mutation rates, such as RNA viruses, quasispecies are highly diverse genotypes that may drastically differ from the general population and often become less viable as they continue to mutate. Using new deep sequencing technology, Marco Vignuzzi of the Pasteur Institute in France hopes to identify such RNA viruses that have managed to retain attenuated strains in order to study these genotypes for possible use in the development of viral vaccines.