Figure 2.

Two-dimensional state space for receptor and coreceptor-mediated viral entry. Each state corresponds to a virus particle bound to m ≤ M receptors and n ≤ N = rM coreceptors. In this example, the fraction of coreceptor-binding spikes to receptor-binding spikes is r = 1/2. The probability fluxes through the fusion and endocytosis pathways are indicated by the red and green arrows, respectively. A representative trajectory of the stochastic process that results in endocytosis is indicated by the blue dashed curve.