Reoviridae

Reoviridae are a genus of non-enveloped (naked) virus particles (diameter 70-80 nm) with a complex structure. The virions are three-layered (outer and inner icosahedral capsid and core shell). The viral genome consisting of 11 discrete segments of double-stranded RNA (ds(+/-)RNA, 18-19Kb) is located in the core shell. This segmentation can lead to new rotavirus variants in double infections via segment exchange (reassortment).

There are various subfamilies, genera and species within the reovirus family. The most important pathogenic viruses include:

• in the subfamily Sedoreovirinae the genus Rotavirus with the species Rotavirus (A to C).
• in the subfamily Spinareovirinae and the genus Coltvirus the species Colorado tick fever virus.

Rotaviruses are the most common pathogens causing hospitalized gastroenteritis in children under five years of age.

Rotaviruses absorb at cellular structures (receptors) that carry neuraminic acid residues. Upon entry into the cytoplasm of the host cell, the outer protein envelope of the virus is shed. The rest of the particle is retained and maintains a connection between the inside of the virus and the environment via numerous pores in the two remaining envelopes.

A distinction is made between 7 serogroups (A-G). Group A rotaviruses are of the greatest epidemiological importance worldwide. The antigenicity of the virus is determined by two proteins (VP4 and VP7) of the viral envelope. These envelope proteins also define the classification of the viruses according to the different serotypes (genotypes). A distinction is made between 16 VP7 types ("G-") and 27 VP4 types ("P-"). The majority of rotavirus diseases in Germany are caused by G1P and G4P rotaviruses, followed by G2P and G9P. Rotaviruses are extremely resistant to the environment.

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