Abstract
Binding to cellular receptors initiates viral replication and dictates sites in the host infected by the virus. As illustrated by mammalian orthoreovirus (reovirus), viruses can bind several types of receptors using distinct capsid components to facilitate the viral entry steps of attachment, internalization, and disassembly. The outer of the two concentric capsids of reovirus virions is formed by four viral proteins, three of which bind receptors. These capsid-receptor interactions mediate stepwise entry of reovirus, dictate viral tropism in infected animals, and expand the viral host range. Engagement of independent receptors by different capsid proteins is a property of many pathogenic viruses and illustrates common themes of receptor use in viral entry and disease.