Porcine epidemic diarrhea virus (PEDV) detection and antibody response in commercial growing pigs.
BACKGROUND
Longitudinal samples from two production sites were used to (1) describe the pattern of PEDV shedding (rRT-PCR) in individual rectal swabs, pen fecal samples, and pen oral fluids (OF); (2) describe the kinetics of PEDV antibody by ELISA (IgA, IgG) testing of pig serum and pen oral fluid samples; and (3) establish cutoffs and performance estimates for PEDV WV ELISAs (IgA, IgG). Site One was PEDV positive; Site Two was PEDV negative. On Site One, pen samples (feces and oral fluids) and pig samples (rectal swabs and sera) were collected both before and after the population was exposed to PEDV.


RESULTS
On Site Two, pen oral fluid samples and individual pig serum samples were negative for both PEDV antibody and nucleic acid. On Site One, PEDV was detected by rRT-PCR at 6 days post exposure (DPE) in all sample types. The last rRT-PCR positives were detected in rectal swabs and oral fluids on 69 DPE. IgG and IgA were detected in oral fluids and serum samples by 13 DPE. Analysis of the PEDV serum IgG WV ELISA data showed that a sample-to-positive (S/P) cutoff of ≥ 0.80 provided a diagnostic sensitivity of 0.87 (95% CI: 0.82, 0.91) and specificity of 0.99 (95% CI: 0.98, 1.00). Serum IgG results declined slowly over the monitoring period, with 60% of serum samples positive (S/P ≥ 0.80) at the final sampling on 111 DPE. Analysis of the PEDV oral fluid IgA WV ELISA found that a cutoff of S/P ≥ 0.80 provided a diagnostic sensitivity of 1.00 (95% CI: 0.92, 1.00) and a diagnostic specificity of 1.00 (95% CI: 0.99, 1.00). The oral fluid IgA response increased through 96 DPE and began to decline at the last sampling on 111 DPE.


CONCLUSIONS
This study showed that oral fluid-based testing could provide an easy and "animal-friendly" approach to sample collection for nucleic acid and/or antibody-based surveillance of PEDV in swine populations.
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1850 Christensen Drive, Ames, IA, 50011-1134, USA.
Jordan
J
Bjustrom-Kraft
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1850 Christensen Drive, Ames, IA, 50011-1134, USA.
Katie
K
Woodard
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1850 Christensen Drive, Ames, IA, 50011-1134, USA.
Luis
L
Giménez-Lirola
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1850 Christensen Drive, Ames, IA, 50011-1134, USA.
Marisa
M
Rotolo
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1850 Christensen Drive, Ames, IA, 50011-1134, USA.|Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Osborn Drive, Ames, IA, 50011, USA.
Chong
C
Wang
Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Osborn Drive, Ames, IA, 50011, USA.
Yaxuan
Y
Sun
Smithfield Hog Production Missouri, 17999 US Highway 65, Princeton, MO, 64673, USA.
Peter
P
Lasley
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1850 Christensen Drive, Ames, IA, 50011-1134, USA.
Jianqiang
J
Zhang
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1850 Christensen Drive, Ames, IA, 50011-1134, USA.
David
D
Baum
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1850 Christensen Drive, Ames, IA, 50011-1134, USA.
Phillip
P
Gauger
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1850 Christensen Drive, Ames, IA, 50011-1134, USA.
Rodger
R
Main
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1850 Christensen Drive, Ames, IA, 50011-1134, USA. jjzimm@iastate.edu.
Jeffrey
http://orcid.org/0000-0002-8107-2422
J
Zimmerman
D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis; D018352:Coronavirus Infections / Q000175:diagnosis / Q000662:veterinary* / Q000821:virology; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005243:Feces / Q000821:virology; D053485:Porcine epidemic diarrhea virus / Q000302:isolation & purification*; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D012007:Rectum / Q000821:virology; D012463:Saliva / Q000821:virology; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis / Q000821:virology*; D017201:Virus Shedding
D000914:Antibodies, Viral
Antibody kinetics; IgA; IgG; Oral fluids; PEDV; Surveillance; Virus shedding