Evolutionary origins of epidemic potential among human RNA viruses

Lu Lu; Liam Brierley; Gail Robertson; Feifei Zhang; Samantha Lycett; Donald Smith; Margo Chase-Topping; Peter Simmonds; Mark Woolhouse

The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/771394 doi: bioRxiv preprint FIGURES Figure 1 . Conceptual model of non-RT RNA virus emergence into human populations. Viruses circulating in the non-human reservoir may not be infective to humans (L1) or have the potential to infect or infect and transmit between humans (L2 and L3/4 respectively). Virus lineages in the reservoir may acquire (thick grey arrows showing rates a, b and c) or lose (thin grey arrows) the capacities to infect and/or transmit in humans through genetic drift -these traits are not under direct selection in the non-human reservoir. L2 and L3/4 viruses in non-human hosts may cross the species barrier and enter human populations. L3/4 (but not L2) viruses may then spread and evolve independently in the human population (multiple grey arrows). Phylogenetic analyses identify past transitions between L1 and L3/4, L1 and L2 and L2 and L3/4 viruses and can be used to estimate the relative values of parameters a, b and c. author/funder. All rights reserved. No reuse allowed without permission.