Reoviridae is a viral family containing viruses famous for causing gastroenteritis and other misfortunes. The name "REO" is actually an acronym referring to respiratory enteric orphan. The first two aspects of the name are the result of research done on the very first reoviruses known, which were isolated from both the respiratory tract and the enteric tract. The "orphan" description is a bit of a misnomer, as it refers to the fact that these original reoviruses did not appear to be associated with any human disease (if a virus cannot be linked with a human syndrom, it is hence orphaned). However, it is now known that human reoviruses do indeed cause human disease. Nevertheless, reoviruses are characterized by their proclivity for infecting across kingdoms: plants and insects, as well as animals. Below is an electron micrograph of a reovirus, the appearance of which is characteristic of the family. The virions have been described as resembling golf balls and Ritz crackers. The latter is perhaps more appropriate, as the most widely distributed of the reoviruses- the rotavirus- is spread by the fecal-oral route. Thus the appearance of the virus can serve as a mnemonic for its transmission.
Copyright 1994 Veterinary
Image courtesy of Professor Stewart McNulty
For more pictures of reoviruses, a great resource is found at the Big Picture Book of Viruses reovirus page.