Genomic characterization of an enterovirus 97 strain isolated in Shandong, China.

The genomic characterization of human enterovirus 97 (EV97) strain isolated from an acute flaccid paralysis case in Shandong province, China in 1999, is described. The strain, designated as 99188/SD/CHN/1999/EV97 (abbreviated as 99188), had a genome of 7394 nucleotides. Compared with other EV97 strains, it had 81.3-83.3% nucleotide similarity and 94.0-95.4% amino acid similarity in VP1 coding region, and it had 81.4% complete genomic similarity with prototype strain BAN99-10355. The most striking feature was the deletion of 18 nucleotides in the 3' end of VP1 coding region, combined with two deletions and one insertion in 5' and 3' untranslated regions. All these findings demonstrated the strain 99188 had a distant genetic relationship with other EV97 strains. In the phylogenetic trees generated from VP1 and 3D sequences of human enterovirus species B (HEV-B), the lineages of strain 99188 were not congruent, suggesting the event of recombination. Similarity plot analysis further provided the evidence of recombination with other strains of HEV-B in P2 and P3 coding region. This is the first finding of EV97 in China and the third genomic sequence of EV97 reported.