Comparison of serum neutralization and enzyme-linked immunosorbent assay on sera from porcine epidemic diarrhea virus vaccinated pigs

Abstract

Background: Porcine epidemic diarrhea virus (PEDV) is an economically important pathogen of swine. Objective: Serum neutralization (SN) and enzyme-linked immunosorbent assay (ELISA) test results as well as the utility of spike proteins S1, S2, and S3 and entire nucleocapsid protein were compared. Animals and methods: Serum samples from 400 pigs vaccinated against PEDV strain SM98P were collected from 78 farms in Korea. SN test and ELISA were performed to confirm the presence of antibodies. For prokaryotic expression of partial fragments of spike protein the size and location of S1, S2, and S3, and full nucleocapsid protein, polymerase chain reaction was performed using specific primers. Results:Comparison of these results demonstrated that there was a correlation between the SN and ELISA results. Sera with higher neutralizing activity also had higher IgG titer. The antibody profiling data presented the correlation of neutralizing activity with the level of spike protein antibody. In particular, the S3 region may have an important role in neutralizing activity. Conclusions: We confirmed that the carboxy-terminal region that includes the endodomain of the S protein induced stronger neutralizing activity than the region that includes the ectodomain. Clinical relevance: The region of the S protein may have a stronger neutralizing KPEDV-9 epitope and could be useful for the evaluation of future PEDV vaccine efficacy.

Specific recombinant proteins of porcine epidemic diarrhea virus are immunogenic, revealing their potential use as diagnostic markers

“…Additionally, levels of NA were more closely correlated with IgA than IgG (Fig. 3B-D), as seen in other studies (Paudel et al, 2014). Abundant anti-PEDV NA have been demonstrated in colostrum on the day of birth, decreasing rapidly in milk by day 3, and gradually declining further from days 3-19 post-farrowing, which may contribute to variable protective capacity .…”

Porcine epidemic diarrhea virus (PEDV) introduction into a naive Dutch pig population in 2014

“…The S1-part of the spike protein is the most variable part between related coronaviruses and there is no cross reactivity with other coronaviruses such as Transmissible gastroenteritis coronavirus (TGEV), Porcine respiratory coronavirus (PRCoV) and Porcine Delta Coronavirus (PDCoV) as previously described (Gimenez-Lirola et al, 2017;Lin et al, 2015b). Because results of immunoassays based on the S protein correlate well with viral neutralization (Paudel et al, 2014), as shown in Supplementary Table 1, we decided to use the VNT as an alternative sero-diagnostic assay.…”

Evolution, antigenicity and pathogenicity of global porcine epidemic diarrhea virus strains

“…The recombinant porcine enteric coronavirus between TGEV and PEDV is in brown. Because viral neutralizing epitopes are located on the S protein, the results of PEDV S protein-based immunoassays correlated well with viral neutralization (VN) titers (Paudel et al, 2014), which is important for clinical protection. In addition, antibodies against the S protein remained detectable for longer periods of time than antibodies to the N protein in the sera of PEDV-infected pigs (Knuchel et al, 1992).…”

“…Truncation of the antigenic site in the N-terminal region could help exclude the possible serological cross-reactivity and enhance the sensitivity/specificity of the immunoassays. Alternatively, PEDV membrane (M) and S proteins could serve as specific antigens for immunoassays (Fan et al, 2015;Gerber et al, 2014;Knuchel et al, 1992;Paudel et al, 2014).…”