Development of a sandwich ELISA to detect virus-like-particles in enterovirus A71 vaccines.

•A sandwich ELISA that recognized intact EV-A71 VLP was developed.•This ELISA recognized EV-A71 from different subgenogroups as well as VLP.•A reference standard was included in the ELISA to develop a quantitative ELISA (Q-ELISA).•Q-ELISA could be used to examine the yield, purity, stability and performance of VLP.