Evolution of vector-borne viral infections: A case study of dengue virus

Dengue virus is transmitted within host populations by mosquito vectors, with its transmission potential modulated by the interactions between the virus and the host immune system. Host populations employ a variety of immune responses to clear or limit infection, while the virus evolves mechanisms to evade or suppress host defenses, thereby facilitating its persistence and spread. Here, an evolutionary-epidemiological model is introduced, integrating virus-host immune system interactions, to couple viral evolutionary dynamics with epidemiological models of disease transmission. The model elucidates the long-term evolutionary outcomes of the virus under different host types and levels of immunity. Using adaptive dynamics, the study explores the effects of host resistance on the evolution of viral virulence. Results demonstrate that at low host immunity levels, the virus tends to evolve towards lower virulence, whereas increased host immunity drives an escalation in viral virulence. By incorporating the Price equation alongside principles of population genetics and evolutionary dynamics, this work identifies critical trade-offs governing viral evolution within the host and provides predictions regarding the virus’s short-term evolutionary trajectory.