Fusion vs. endocytosis in receptor/coreceptor-mediated entry of enveloped viruses
Viral infection requires that host cell receptors and possibly coreceptors bind to glycoproteins, or "spikes," on the viral membrane. Both fusion and endocytosis have been observed to be viable entry pathways for many viruses. We develop a stochastic model for the entry of viruses that require receptor engagement for endocytosis and coreceptor engagement for fusion. In this model, coreceptors bind only to viral spikes that have a receptor bound. The relative probabilities of viral entry by fusion and endocytosis are computed as functions of the receptor and coreceptor binding rates, and number of spikes.