To evaluate an assay permitting amplification of target 5′-untranslated region (5′-UTR) sequences directly from clinical specimens and distinction among serotypes of enterovirus (EV).

A total of 518 rectal swabs and 148 nasal swabs tested positive by pan-enterovirus real-time PCR were collected. 5′-UTR and the viral protein 1 (VP1) gene fragments were amplified and sequenced separately for serotyping. The inconsistent samples by 5′-UTR and VP1 serotyping were further determined by using the serotype-specific RT-PCR.

A total of 553 (83.0%) samples were detected by 5′-UTR serotyping and 318 (47.7%) were detected by VP1 serotyping in all 666 positive specimens, and there was significant difference in the detection rates between two methods in rectal and nasal swabs (P<0.001). For the rectal swabs, the mainly detected serotypes were CoxA6 (217), CoxA16 (88), EVA71 (40), CoxA10 (28) and CoxA4 (27) by 5′-UTR serotyping. Compared with the VP1 serotyping, the sensitivity and specificity of 5′-UTR serotyping were 57.1%-100% and 67.4%-98.1% respectively, with varied consistence with serotypes (kappa value 0.214-0.283). For the nasal swabs, the most frequently detected serotype was EVD68, with the sensitivity of 100%, the specificity of 91.1%, and the poor consistence (kappa value 0.217). CoxA6, CoxA16, EVA71, CoxA10 and EVD68 were further confirmed by serotype-specific RT-PCR. Using VP1 serotyping combined with serotype-specific RT-PCR as a reference method , the effect of performance of 5′-UTR serotyping on diagnosis was increased.

The performances of 5′-UTR serotyping in enterovirus vary with serotypes. The application of 5′-UTR serotyping should be considered comprehensively according to the purpose of the study.

Enterovirus; 5′-untranslated region; Reverse transcription-polymerase chain reaction; Sequencing; Serotyping