Evaluation of purified recombinant spike fragments for assessment of the presence of serum neutralizing antibodies against a variant strain of porcine epidemic diarrhea virus
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Since 2010, variant strains of porcine epidemic diarrhea virus (PEDV) have caused disasters in the pork industry. The spike (S) protein, as the major immunity-eliciting antigen, has previously been used for serological testing and has been found to correlate significantly with the results of the serum neutralization (SN) test. However, further evaluation of this method is needed as new epidemic strains of PEDV emerge. Hence, the main objective of this study was to assess sow sera and determine the correlation between enzyme-linked immunosorbent assay (ELISA) results (involving a newly isolated GDS01 virus-based ELISA and ELISAs based on seven recombinant fragments comprising overlapping S1 and partial S2 sequences) and SN titers. Furthermore, we determined the reliability of the ELISAs based on receiver operating characteristics (ROC) curve analyses. For the most promising ELISA, i.e., the SP4 ELISA, the correlation coefficient (r) and the area under curve (AUC) were determined to be 0.6113 and 0.8538, respectively. In addition, we analyzed the homology of the SP4 sequences obtained from different strains (including vaccine strains) and found that various strains showed a high degree of homology in this region. Thus, we conclude that SP4 is a promising serological testing protein for use in the field.
KeywordsPorcine epidemic diarrhea virus (PEDV) spike protein enzyme-linked immunosorbent assay serum neutralization test
This work was supported by the National Key Research and Development Program (2016YFD0500101).
JH and YZ designed the experiments. JH, YZ, ZW, and XZ carried out the experiments. SF analyzed the data. JH and YZ wrote the manuscript. YC supervised the study and finalized the manuscript. All authors read and approved the final manuscript.
Compliance with Ethics Guidelines
The authors declare that they have no conflict of interest. The animal study was supervised by the Institutional Animal Care and Use Committee of the Sun Yat-sen University (IACUC DD-17-0403) and used in accordance with regulation and guidelines of this committee.
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