Fig 1. Model schematic and relation to results from vector competence experiments.

A: In a vector competence experiment, mosquitoes are provided a blood meal containing virus. Individual mosquitoes ingest G_v virions. After virions enter the midgut, infection must be initiated as shown in B. B: Ingested virions infect susceptible midgut epithelial cells (M_c) at rate β and can spread between cells at rate α. New virions are produced at rate γ to produce free virus M_v and can escape through the basal lamina at rate (ρ). Here only infected hemocoel cells are modelled (H_c) to represent dissemination and free virus in the hemocoel (H_v). Virus is cleared at all stages at rate μ_v. We also make the simplifying assumption that parameter values are the same across tissues. C: Vector competence experiments usually compare at least two treatments or mosquito species to quantify the ability of mosquitoes, under set experimental conditions to become infected by and subsequently transmit virus; here shown as conceptual results for two different mosquito species. In simulations of the stochastic model and as realised in experiments, multiple individuals can be tracked and the proportion which develop a midgut infection quantified in addition to the proportion infected which develop a disseminated infection. Here we argue that these processes should be seen as functions of initial number of input virions in the blood meal and time post blood meal respectively.