Dataset Information

Development of an indirect ELISA, blocking ELISA, fluorescent microsphere immunoassay and fluorescent focus neutralization assay for serologic evaluation of exposure to North American strains of Porcine Epidemic Diarrhea Virus.

ABSTRACT: Recent, severe outbreaks of porcine epidemic diarrhea virus (PEDV) in Asia and North America highlight the need for well-validated diagnostic tests for the identification of PEDV infected animals and evaluation of their immune status to this virus. PEDV was first detected in the U.S. in May 2013 and spread rapidly across the country. Some serological assays for PEDV have been previously described, but few were readily available in the U.S. Several U.S. laboratories quickly developed indirect fluorescent antibody (IFA) assays for the detection of antibodies to PEDV in swine serum, indicating prior exposure. However, the IFA has several disadvantages, including low throughput and relatively subjective interpretation. Different serologic test formats have advantages and disadvantages, depending on the questions being asked, so a full repertoire of tests is useful. Therefore, the objective of this study was to develop and validate multiple improved serological assays for PEDV, including an indirect ELISA (iELISA); a highly specific monoclonal antibody-based blocking ELISA (bELISA); fluorescent microsphere immunoassays (FMIA) that can be multiplexed to monitor exposure to multiple antigens and pathogens simultaneously; and a fluorescent focus neutralization assay (FFN) to measure functional virus neutralizing antibodies.A recombinant North American nucleoprotein (NP) based iELISA was developed and validated along with a bELISA using newly developed PEDV-NP specific biotinylated monoclonal antibodies (mAbs) and an FMIA using magnetic beads coupled with expressed NA PEDV-NP. Receiver operating characteristic (ROC) analysis was performed using swine serum samples (iELISA n = 1486, bELISA n = 1186, FMIA n = 1420). The ROC analysis for the FMIA showed estimated sensitivity and specificity of 98.2 and 99.2 %, respectively. The iELISA and bELISA showed a sensitivity and specificity of 97.9 and 97.6 %; and 98.2 and 98.9 %, respectively. Inter-rater (kappa) agreement was calculated to be 0.941 between iELISA and IFA, 0.945 between bELISA and IFA and 0.932 between FMIA and IFA. Similar comparative kappa values were observed between the iELISA, bELISA and FMIA, which demonstrated a significant level of testing agreement among the three assays. No cross-reactivity with the closely related coronaviruses, transmissible gastroenteritis virus (TGEV) or porcine respiratory coronavirus (PRCV) was noted with these assays. All three assays detected seroconversion of naïve animals within 6-9 days post exposure. The FFN assay allows relative quantitation of functional neutralizing antibodies in serum, milk or colostrum samples.Well-validated iELISA, bELISA and FMIA assays for the detection of PEDV antibodies were developed and showed good correlation with IFA and each other. Each assay format has advantages that dictate how they will be used in the field. Newly developed mAbs to the PEDV-NP were used in the bELISA and for expediting FFN testing in the detection and quantitation of neutralizing antibodies. In addition, these PEDV mAbs are useful for immunohistochemistry, fluorescent antibody staining and other antigen-based tests. Measurement of neutralizing antibody responses using the FFN assay may provide a valuable tool for assessment of vaccine candidates or protective immunity.

SUBMITTER: Okda F

PROVIDER: S-EPMC4522128 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Development of an indirect ELISA, blocking ELISA, fluorescent microsphere immunoassay and fluorescent focus neutralization assay for serologic evaluation of exposure to North American strains of Porcine Epidemic Diarrhea Virus.

Okda Faten F Liu Xiaodong X Singrey Aaron A Clement Travis T Nelson Julie J Christopher-Hennings Jane J Nelson Eric A EA Lawson Steven S

BMC veterinary research 20150801

<h4>Background</h4>Recent, severe outbreaks of porcine epidemic diarrhea virus (PEDV) in Asia and North America highlight the need for well-validated diagnostic tests for the identification of PEDV infected animals and evaluation of their immune status to this virus. PEDV was first detected in the U.S. in May 2013 and spread rapidly across the country. Some serological assays for PEDV have been previously described, but few were readily available in the U.S. Several U.S. laboratories quickly dev ...[more]

PMID: 26232106

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Project description:BackgroundA novel porcine deltacoronavirus (PDCoV), also known as porcine coronavirus HKU15, was reported in China in 2012 and identified in the U.S. in early 2014. Since then, PDCoV has been identified in a number of U.S. states and linked with clinical disease including acute diarrhea and vomiting in the absence of other identifiable pathogens. Since PDCoV was just recently linked with clinical disease, few specific antibody-based reagents were available to assist in diagnosis of PDCoV and limited serological capabilities were available to detect an antibody response to this virus. Therefore, the overall objective of this project was to develop and validate selected diagnostic reagents and assays for PDCoV antigen and antibody detection.ResultsThe nucleoprotein of PDCoV was expressed as a recombinant protein and purified for use as an antigen to immunize mice for polyclonal, hyperimmune sera and monoclonal antibody (mAb) production. The resulting mAbs were evaluated for use in fluorescent antibody staining methods to detect PDCoV infected cells following virus isolation attempts and for immunohistochemistry staining of intestinal tissues of infected pigs. The same antigen was used to develop serological tests to detect the antibody response to PDCoV in pigs following infection. Serum samples from swine herds with recent documentation of PDCoV infection and samples from expected naïve herds were used for initial assay optimization. The tests were optimized in a checkerboard fashion to reduce signal to noise ratios using samples of known status. Statistical analysis was performed to establish assay cutoff values and assess diagnostic sensitivities and specificities. At least 629 known negative serum samples and 311 known positive samples were evaluated for each assay. The enzyme linked immunosorbent assay (ELISA) showed diagnostic sensitivity (DSe) of 96.1% and diagnostic specificity (DSp) of 96.2%. The fluorescent microsphere immunoassay (FMIA) showed a DSe of 95.8% and DSp of 98.1%. Both ELISA and FMIA detected seroconversion of challenged pigs between 8-14 days post-infection (DPI). An indirect fluorescent antibody (IFA) test was also developed using cell culture adapted PDCoV for comparative purposes.ConclusionThese new, specific reagents and serological assays will allow for improved diagnosis of PDCoV. Since many aspects of PDCoV infection and transmission are still not fully understood, the reagents and assays developed in this project should provide valuable tools to help understand this disease and to aid in the control and surveillance of porcine deltacoronavirus outbreaks.

Dataset Information

Development of an indirect ELISA, blocking ELISA, fluorescent microsphere immunoassay and fluorescent focus neutralization assay for serologic evaluation of exposure to North American strains of Porcine Epidemic Diarrhea Virus.

Publications

Development of an indirect ELISA, blocking ELISA, fluorescent microsphere immunoassay and fluorescent focus neutralization assay for serologic evaluation of exposure to North American strains of Porcine Epidemic Diarrhea Virus.

Similar Datasets

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