Cross-scale dynamics and the evolutionary emergence of infectious diseases

Sebastian J. Schreiber; Ruian Ke; Claude Loverdo; Miran Park; Priyanna Ahsan; James O. Lloyd-Smith

Our results focus on systems where there is one major rate-limiting step to emergence, and the viral population can be represented by one wild-type and one mutant strain. This is a simplification of most viral emergence problems, but will apply directly to systems where a single large-effect mutation is the primary barrier to emergence of a supercritical strain, as for Venezuelan equine encephalitis virus emerging from rodents to horses [104] . While it is possible to extend our exact computations and analysis of the cross-scale reproductive number of a mutant virion to systems with multiple mutational steps, the present analysis already provides insights into more complex evolutionary scenarios. For evolutionary trajectories that proceed through a fixed series of genotypes, the probability of emergence can be approximated by extension of our equation (4) , as in previous work [12, 13, 15] . If emergence requires multiple mutational steps All rights reserved. No reuse allowed without permission.