Mosaic genome structure of echovirus type 30 that circulated in Taiwan in 2001

An echovirus type 30 (E30) outbreak occurred in Taiwan in 2001. In this study, one 1998 and nineteen 2001 enterovirus isolates from cerebrospinal fluid (CSF) of children with meningitis were genetically analyzed. Although negative results were obtained using the E30-specific monoclocal antibody in an immunofluorescent assay (IFA) test of all 20 isolates, molecular typing by partial VP1 sequences and subsequent neutralization test identified them as E30. Among those, seven of them were misidentified as echovirus type 4 (E4) when E4-specific monoclonal antibody was used. Complete genome sequences of one E30 isolate (TW-2513) that were IFA-positive to E4 and another (TW-3182) that was IFA-negative to both E30 and E4 were determined and analyzed. The overall percentage nucleotide identity in the structural coding region (P1) between these two isolates is 98.4, while those in the nonstructural regions P2 and P3 are only 83.2 and 84.4, respectively, indicating that the two 2001 Taiwanese E30 strains were probably recombinant. Recombination analysis of these two E30 genomes revealed that their genome structures are mosaic, which might have been formed gradually and frequently over time.