ABSTRACT
This chapter describes a number of viruses which are possibly picornaviruses on the basis of an appropriate complement of proteins and ribonucleic acid, size and sedimentation coefficient. The family Picornaviridae is divided into four genera: the Enteroviruses, the Cardioviruses, the Rhinoviruses, and the Aphthoviruses. There have been numerous reports of small viruses which may be picornaviruses, associated with marine and fresh-water invertebrates. Relatively few viruses of insects have been studied in sufficient detail to be classified as picornaviruses by the International Committee on Taxonomy of Viruses. There is a strong case, however, for deriving a detailed comparative knowledge of the insect and mammalian picornaviruses in order to eliminate the possibility of vertebrate disease resulting from the use of picornaviruses as biological control agents. The classification of the first small virus isolated from R. padi continues to be evaluated but there is evidence from the replicative events that it is not a picornavirus.
