title: Probability of detecting influenza A virus subtypes H1N1 and H3N2 in individual pig nasal swabs and pen-based oral fluid specimens over time.
abstract: The probability of detecting influenza A virus (IAV) by virus isolation (VI), point-of-care (POC) antigen detection, and real-time reverse-transcription polymerase chain reaction (rRT-PCR) was estimated for pen-based oral fluid (OF) and individual pig nasal swab (NS) specimens. Piglets (n=82) were isolated for 30 days and confirmed negative for porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae, and IAV infections. A subset (n=28) was vaccinated on day post inoculation (DPI) -42 and -21 with a commercial multivalent vaccine. On DPI 0, pigs were intratracheally inoculated with contemporary isolates of H1N1 (n=35) or H3N2 (n=35) or served as negative controls (n=12). OF (n=370) was collected DPI 0-16 and NS (n=924) DPI 0-6, 8, 10, 12, 14, 16. The association between IAV detection and variables of interest (specimen, virus subtype, assay, vaccination status, and DPI) was analyzed by mixed-effect repeated measures logistic regression and the results used to calculate the probability (pˆ) of detecting IAV in OF and NS over DPI by assay. Vaccination (p-value<0.0001), DPI (p-value<0.0001), and specimen-assay interaction (p-value<0.0001) were significant to IAV detection, but virus subtype was not (p-value=0.89). Vaccination and/or increasing DPI reduced pˆ for all assays. VI was more successful using NS than OF, but both VI and POC were generally unsuccessful after DPI 6. Overall, rRT-PCR on OF specimens provided the highest pˆ for the most DPIs, yet significantly different results were observed between the two laboratories independently performing rRT-PCR testing.
authors.affiliation: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA. christa-goodell@idexx.com
authors.forename: Christa K
authors.initials: CK
authors.lastname: Goodell
authors.forename: John
authors.initials: J
authors.lastname: Prickett
authors.forename: Apisit
authors.initials: A
authors.lastname: Kittawornrat
authors.forename: Fanghong
authors.initials: F
authors.lastname: Zhou
authors.forename: Rolf
authors.initials: R
authors.lastname: Rauh
authors.forename: William
authors.initials: W
authors.lastname: Nelson
authors.forename: Cate
authors.initials: C
authors.lastname: O'Connell
authors.forename: Angela
authors.initials: A
authors.lastname: Burrell
authors.forename: Chong
authors.initials: C
authors.lastname: Wang
authors.forename: Kyoung-Jin
authors.initials: KJ
authors.lastname: Yoon
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Zimmerman
mesh_terms: D000818:Animals; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000302:isolation & purification*; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics / Q000302:isolation & purification*; D009055:Mouth / Q000378:metabolism / Q000821:virology*; D009666:Nose / Q000821:virology*; D011336:Probability; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis / Q000821:virology*; D013997:Time Factors
keywords: Influenza A virus; Nasal swabs; Oral fluids; PCR; Swine; Virus isolation