Agent-Based Simulation of Evolution of Pathogen and its Implication of Long-term Strategy against Infectious Diseases

While influenza is a quite common infectious disease, the pattern of its global circulation and evolutionary dynamics still pose many questions to be answered. “Limited diversity” observed in the viral evolution of seasonal influenza is the one that has not been fully investigated. Influenza viruses have single-stranded RNA, which lacks an error correction mechanism and thus results in the high mutation rate of the genome. Thus, while continual changes accumulate in the viruses as time passes, there is always a chance for a new genetic lineage to diverge, which could theoretically result in ever-increasing explosive diversity. However, in reality, the diversity of the existing viruses is relatively limited to a certain extent at the population level and at any particular point in time. In the first part of this paper, to understand this fundamental evolutionary behavior, we propose a multi-layered, agent-based simulation that combines three sub-models: 1) an epidemic model, which describes how viruses are circulated among a host population, 2) immunologicalmodel, which describes the interaction among hosts and pathogens, and 3) a viral evolution model, which describes how viruses change during a time course. In the last part of the paper, we focus the problem of infectious diseases from the point of view of co-evolutionary dynamics between hosts and pathogens, and discuss the possibility for symbiotic way of solution