Development of an indirect ELISA method based on the VP1 protein for detection of IgG antibodies against porcine sapelovirus.

Porcine sapelovirus (PSV) is a newly emerging enterovirus that is widely prevalent in China. Since there is no clinical serological testing for PSV, the objective of this study was to develop an indirect enzyme-linked immunosorbent assay (i-ELISA) for detection of PSV immunoglobulin G (IgG) antibody in pigs. A PSV strain, named SHPD202148, was first isolated from the fecal samples of piglets. Its structural protein, VP1, was prokaryotic-expressed in the pET expression system, followed by purification. Using the recombinant protein with reactogenicity as coating antigen, an i-ELISA, characterized by high sensitivity and specificity, had a detection limit at 1:12 800 dilution with a determined cutoff value of 0.352. Finally, field sera collected from different pig herds were tested in parallel by the serum neutralization (SN) test. The result showed that 126 samples were positive and 36 were negative, with an agreement of 97.0% in both cases. This i-ELISA can be used as an alternative serological test for detecting antibodies against PSV in blood serum.