Molecular phylogeny and proposed classification of the simian picornaviruses

The simian picornaviruses were isolated from various primate tissues during the development of general tissue culture methods in the 1950s to 1970s or from specimens derived from primates used in biomedical research. Twenty simian picornavirus serotypes are recognized, and all are presently classified within the Enterovirus genus. To determine the phylogenetic relationships among all of the simian picornaviruses and to evaluate their classification, we have determined complete VP1 sequences for 19 of the 20 serotypes. Phylogenetic analysis showed that A13, SV19, SV26, SV35, SV43, and SV46 are members of human enterovirus species A, a group that contains enterovirus 71 and 11 of the coxsackie A viruses. SA5 is a member of human enterovirus species B, which contains the echoviruses, coxsackie B viruses, coxsackievirus A9, and enterovirus 69. SV6, N125, and N203 are related to one another and, more distantly, to species A human enteroviruses, but could not be definitely assigned to a species. SV4 and SV28 are closely related to one another and to A-2 plaque virus, but distinct from other enteroviruses, suggesting that these simian viruses are members of a new enterovirus species. SV2, SV16, SV18, SV42, SV44, SV45, and SV49 are related to one another but distinct from viruses in all other picornavirus genera, suggesting that they may comprise a previously unknown genus in Picornaviridae. Several simian virus VP1 sequences (N125 and N203; SV4 and SV28; SV19, SV26, and SV35; SV18 and SV44; SV16, SV42, and SV45) are greater than 75% identical to one another (and/or greater than 85% amino acid identity), suggesting that the true number of distinct serotypes among the viruses surveyed is less than 20.