Simulating Limited Diversity in Evolution of Influenza

In many cases, analyses on infectious diseases focus on how the epidemic arises, spreads, and whether diminishes or gets fixated among host populations under particular conditions, without taking the evolutinary perspective into account. With some infectious diseases, however, the pathogens themselves evolve comparatively rapidly during the time course, so that the co-evolutionary dynamics among hosts and pathogens should be considered at the same time. In this paper, we fo-cus on influenza and propose a bilayered, multi-agent-based simulation that combines an epidemic model and a viral evo-lution model. The latter model includes genomic segments of the viruses whose evolutionary paths are guided by two se-lective pressures; one originates from the viral-host immune interaction and the other originates from intra-genomic con-straints within the virus. By including such a micro-level rep-resentation in the model, we show mechanisms that generate the limited diversity of viruses, which is a fundamental yet unexplained temporal characteristic observed in the evolution of influenza. The full version of this work has already been published in (Sasaki, 2013)