Structure, function and evolution of picornaviruses.

Picornaviruses are a diverse family of small, RNA viruses which include several pathogens of man and animals. They are divided, on the basis of physicochemical properties such as acid stability and buoyant density, into four main genera: enteroviruses, rhinoviruses, cardioviruses and aphthoviruses. The enteroviruses are the most important in terms of human pathogenicity and include the polioviruses, coxsackieviruses and Echoviruses, together with enterovirus types 68 to 72. There are also several bovine and porcine serotypes. Rhinoviruses include 100 human serotypes (the major cause of the common cold) and two bovine serotypes. The cardioviruses, the best studied being encephalomyocarditis virus (EMCV), all belong to one serotype and are generally considered to be murine viruses• The seven serotypes of foot-and-mouth disease virus (FMDV) constitute the aphthoviruses. Altogether there are over 230 serotypes and their medical and economic importance have ensured that they have been the subject of a great deal of research (see the review by Rueckert, 1985)• Progress has been facilitated by the fact that the viruses contain a relatively small amount of genetic information and can thus be studied readily at the molecular level, if necessary by complete nucleotide sequence determination. The ability to crystallize picornaviruses and the application of X-ray crystallography to complete virus