An international consortium, led by Delft University of Technology and the University of North Carolina, has for the first time succeeded in probing the molecular origins of recombination in RNA viruses. Hiccups during the copying process of viruses cause recombination to take place: the exchange of segments of viral RNA. While this can lead to the emergence of new virus variants, the mechanism can also be exploited to induce non-viable defective viruses. The research is published today in Molecular Cell.