title: Porcine reproductive and respiratory syndrome virus (PRRSV) surveillance using pre-weaning oral fluid samples detects circulation of wild-type PRRSV.
abstract: Oral fluid samples collected from litters of piglets (n=600) one day prior to weaning were evaluated as a method to surveil for porcine reproductive and respiratory syndrome virus (PRRSV) infections in four sow herds of approximately 12,500 sow each. Serum samples from the litters' dam (n=600) were included for comparison. All four herds were endemically infected with PRRSV and all sows had been vaccinated ≥ 2 times with PRRSV modified-live virus vaccines. After all specimens had been collected, samples were randomized and assayed by PRRSV real-time reverse transcription polymerase chain reaction (RT-qPCR) and four PRRSV antibody ELISA assays (IgM, IgA, IgG, and Commercial Kit). All sow serum samples were negative by PRRSV RT-qPCR, but 9 of 600 oral fluid samples tested positive at two laboratories. Open reading frame 5 (ORF5) sequencing of 2 of the 9 positive oral fluid samples identified wild-type viruses as the source of the infection. A comparison of antibody responses in RT-qPCR positive vs. negative oral fluid samples showed significantly higher IgG S/P ratios in RT-qPCR-positive oral fluid samples (mean S/P 3.46 vs. 2.36; p=0.02). Likewise, sow serum samples from RT-qPCR-positive litter oral fluid samples showed significantly higher serum IgG (mean S/P 1.73 vs. 0.98; p<0.001) and Commercial Kit (mean S/P 1.97 vs. 0.98; p<0.001) S/P ratios. Overall, the study showed that pre-weaning litter oral fluid samples could provide an efficient and sensitive approach to surveil for PRRSV in infected, vaccinated, or presumed-negative pig breeding herds.
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
authors.forename: Apisit
authors.initials: A
authors.lastname: Kittawornrat
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA; Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Yaowalak
authors.initials: Y
authors.lastname: Panyasing
authors.affiliation: IDEXX Laboratories, Inc., Westbrook, ME 04092, USA.
authors.forename: Christa
authors.initials: C
authors.lastname: Goodell
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA; Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Ames, IA 50011, USA.
authors.forename: Chong
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
authors.forename: Phillip
authors.initials: P
authors.lastname: Gauger
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Harmon
authors.affiliation: Tetracore(®), Inc., Rockville, MD 20850, USA.
authors.forename: Rolf
authors.initials: R
authors.lastname: Rauh
authors.affiliation: Seaboard Farms, Inc., Guymon, OK 73942, USA.
authors.forename: Luc
authors.initials: L
authors.lastname: Desfresne
authors.affiliation: Seaboard Farms, Inc., Guymon, OK 73942, USA.
authors.forename: Ian
authors.initials: I
authors.lastname: Levis
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA. Electronic address: jjzimm@iastate.edu.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Zimmerman
mesh_terms: D000818:Animals; D000833:Animals, Suckling / Q000821:virology; D000914:Antibodies, Viral / Q000032:analysis / Q000097:blood; D004279:DNA, Viral / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D005838:Genotype; D007070:Immunoglobulin A / Q000032:analysis; D008297:Male; D016366:Open Reading Frames; D011159:Population Surveillance / Q000379:methods; D019318:Porcine Reproductive and Respiratory Syndrome / Q000175:diagnosis* / Q000453:epidemiology* / Q000517:prevention & control; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D012463:Saliva / Q000737:chemistry / Q000821:virology*; D016036:Seroepidemiologic Studies; D034421:Sus scrofa / Q000821:virology; D013552:Swine / Q000821:virology; D014613:Vaccines, Attenuated / Q000008:administration & dosage
chemical_list: D000914:Antibodies, Viral; D004279:DNA, Viral; D007070:Immunoglobulin A; D014613:Vaccines, Attenuated
keywords: Oral fluid antibody; PRRSV; RT-qPCR; Surveillance