Environmental Perturbations that Influence Arboviral Host Range: Insights into Emergence Mechanisms

This chapter attempts to describe how environmental perturbations provide emergence opportunities for highly adaptable viral pathogens, capable of rapidly evolving and exploiting unique niches generated during ecological change. It provides several examples where arboviruses have emerged as a direct result of deforestation, changes in agricultural practices, urbanization, and increases in temperature. As with all RNA viruses, arboviruses contain inherently error-prone RNA-dependent RNA polymerases that lack proofreading capacity and may generate approximately 1 mutation per 10000 nucleotides replicated. Although most mutations have either a neutral or detrimental fitness effect on the virus and are either neutrally or negatively selected, respectively, a small percentage impart a fitness benefit to the virus in a given environment. It is these adaptations on which the chapter is focused, with fitness defined as the replicative (and/or transmissibility) success of the virus in a changing environment.