Animal enteroviruses: a glimpse of a wide evolutionary landscape

The genus Enterovirus (family Picornaviridae) contains numerous viruses, most of which have been identified in humans. Among them, the three serotypes of poliovirus, coxsackieviruses A and B, echoviruses, rhinoviruses and other enteroviruses (EVs) responsible in humans for a wide spectrum of clinical manifestations. There are also 60 identified EVs in different mammals. Some have been found in both humans and animals, demonstrating the possibility of zoonotic transmission of certain EVs. Compared to human EVs, genetic and epidemiological data about animal EVs are scarce. However, the detection of EVs in various species of mammals and their presence on all continents suggest that the number of EVs still to be discovered is very important. Some EVs found in animals have characteristics never seen in human EVs. Furthermore, the unique phylogenetic relationships observed between some animal EVs raise interesting questions about the rules that govern the evolution of these viruses. The aim of this review is to present the salient data on animal EVs and to highlight the questions they raise.