Nucleotide sequencing and phylogenetic analysis of 10 recognized prototype strains of the porcine enterovirus (PEV) cytopathic effect (CPE) group I reveals a close relationship of the viral genomes to the previously sequenced strain F65, supporting the concept of a reclassification of this virus group into a new picornavirus genus. Also, nucleotide sequences of the polyprotein-encoding genome region or the P1 region of 28 historic strains and recent field isolates were determined. The data suggest that several closely related but antigenically and molecular distinct serotypes constitute one species within the proposed genus Teschovirus. Based on sequence data and serological data, we propose a new serotype with strain Dresden as prototype. This hitherto unrecognized serotype is closely related to porcine teschovirus 1 (PTV-1, former PEV-1), but induces typespecific neutralizing antibodies. Sequencing of field isolates collected from animals presenting with neurological disorders prove that other serotypes than PTV-1 may also cause polioencephalomyelitis of swine.The porcine enteroviruses (PEVs) were described as causative agents of severe and mild neurological disorders known as Teschen/Talfan disease (16, 39), reproductive failure (10), pneumonia (27), diarrhea (13), and dermal lesions of swine (25). Due to the physicochemical properties of their virions, they were previously classified as enteroviruses. Several distinct serotypes have been described (3,5,6,12,17,23,36). Based on parameters such as (i) cytopathic effect (CPE), (ii) replication properties in various host cell lines, and (iii) serological assays, the PEVs were divided into three CPE groups: I (serotypes 1 to 7 and 11 to 13), II (serotype 8), and III (serotypes 9 and 10) (23, 42). Recently, partial genome regions of members of each CPE group-Porcine teschovirus 1 (PTV-1) strains Talfan and F65 (9,20), PEV-8 (J. H. Peng, R. P. Kitching, and N. J. Knowles, unpublished data), and PEV-9 (J. H. Peng, J. W. McCauley, R. P. Kitching, and N. J. Knowles, unpublished data)-were cloned and sequenced. Analysis of available genome information revealed that PEV-9 and PEV-10 are typical enteroviruses, while PEV-8 appears to be closely related to both enteroviruses and rhinoviruses. However, the genome of strain F65 (a member of CPE group I) exhibits unique features suggesting the reclassification into a new picornavirus taxon. The new genus was named Teschovirus, with F65 as a member of the species Porcine teschovirus (22). In this study, we will use the proposed name "teschovirus" as synonymous to "PEV CPE group I."Since the molecular properties of other members of PEV CPE group I and their relationship to F65 are still unclear, we aimed to gain further information on these viruses. For this purpose, the genomes of the prototype strains of PEV-1 to -7 and PEV-11 to -13 (proposed names PTV-1 to -10 [ Table 1]) were sequenced and compared to genomes of other members of the family Picornaviridae. Moreover, several historic strains and recent field isolates were i...
