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18 Early Steps in Reovirus Infection of Cells

Max L. Nibert, Bernard N. Fields


When an animal virus is introduced to a cell which it can infect, a series of ordered steps commences. These steps involve particular virus/cell interactions and, depending on the type of virus, can include binding by viral attachment proteins to receptors on the cell surface, endocytosis and uptake of viral particles into cellular vacuoles, interaction of viral proteins with a cellular membrane, penetration of the membrane so that components of the viral particle enter the cytoplasm, localization of viral components to particular sites within the cell interior, and initiation of the viral genetic program. A striking relationship can be seen between the structure, or form, of a virus and its activity, or function, at particular steps in the entry process. In general, the early steps in infection are linked to a series of structural changes in the infecting viral particle. These structural changes are sometimes characterized by the terms uncoating and disassembly; however, these terms seem too passive and limited in scope to describe the complex structural transitions that occur at these steps.

In this chapter, we discuss how different structural forms of the mammalian reoviruses interact with mammalian cells at different early steps in infection (for another review of this subject, see Nibert et al. 1991a). We begin by characterizing three forms of reovirus particles—virions, ISVPs, and cores—that mediate three discrete functions in the initiation of infection and by describing dramatic structural transitions that distinguish these particle forms. We then discuss the individual steps of attachment to...

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