Reoviruses

Reoviruses

Introduction

The family Reoviridae is divided into nine genera, of which only four genera cause human diseases. These genera are Orbivirus, Orthoreovirus, Rotavirus, and Coltivirus. Other genera infect onlythe plants, insects, and fish. The Reoviridae viruses are non-enveloped viruses with double-layered protein capsids. The inner capsid layer shows well-defined subunits, whereas the outer layer of some viruses (e.g., rotaviruses and orbiviruses) lacks these well-defined structures. The genome consists of a 10–12-segmented double-stranded RNA with a total genome size of 16–27 kbp. The virus core contains many enzymes essential for transcrip-tion and capping of viral RNA. These viruses are unusually resis-tant to heat, a wide pH (3.0–9.0), and to lipid solvents but are sensitive to 95% ethanol, phenol, and chlorine. Reoviruses asso-ciated with human diseases are listed in Table 63-1.