Authors Korakrit Poonsuk, Ting-Yu Cheng, Ju Ji, Jeffrey Zimmerman and Luis Giménez-Lirola

Background

“Meat juice”, the transudate produced as frozen muscle tissue undergoes the process of thawing, is composed of intracellular fluid, extracellular fluid, blood, and lymph [1]. As such, meat juice contains antibodies, albeit at a lower concentration than serum [1], and diagnostically sensitive and specific meat juice antibody ELISAs have been described for porcine reproductive and respiratory syndrome virus (PRRSV), influenza A virus, Mycoplasma hyopneumoniae, Salmonella spp., Trichinella spp., Yersinia enterocolitica, and Toxoplasma gondii [2]. Meat juice is particularly compatible with abattoir-based surveillance because muscle tissue samples are easily collected at slaughter [2, 3]. Typically, meat samples collected in the abattoir are hard-frozen and then thawed after arrival at the laboratory to produce the specimen. Samples can be stored frozen or tested immediately. Abattoir-based meat juice surveillance or monitoring has been described for salmonella, Toxoplasma gondii, and PRRSV [2, 4]. Therefore, the objective of this study was to evaluate the detection of porcine epidemic diarrhoea virus (PEDV)-specific IgG and IgA in individual serum and meat samples (longissimus dorsi muscle).

The study

The diagnostic performance of porcine epidemic diarrhoea virus (PEDV) IgG and IgA ELISAs was evaluated using paired serum and meat juice samples collected from PEDV-negative (n = 50) and PEDV-inoculated pigs (n = 87).

Serum samples were tested by PEDV (IgG, IgA) ELISAs using a procedure performed routinely at the Iowa State University-Veterinary Diagnostic Laboratory (ISU-VDL). Serum samples were tested using PEDV serum IgG and IgA ELISA procedures as routinely performed at the Iowa State University-Veterinary Diagnostic Laboratory (ISU-VDL). Serum samples were diluted 1:50 and conjugate concentrations were 1/20,000 for IgG and 1/3000 for IgA.

Meat juice samples were tested using the serum PEDV IgG and IgA ELISAs, with modifications, i.e., meat juice samples were diluted 1:25 and conjugate concentrations were 1/40,000 for IgG and 1/10,000 for IgA.

Receiver operator characteristic (ROC) curve analyses were used to estimate diagnostic sensitivities and specificities over a range of sample-to-positive (S/P) cutoffs.

Consistent with previous reports, this study showed that the PEDV IgG and IgA meat juice ELISAs provided excellent diagnostic performance and suggest that meat juice recovered from samples collected at slaughter could be used in routine PEDV surveillance.

^{Korakrit Poonsuk, Ting-Yu Cheng, Ju Ji, Jeffrey Zimmerman and Luis Giménez-Lirola (2018). Detection of porcine epidemic diarrhea virus (PEDV) IgG and IgA in muscle tissue exudate (“meat juice”) specimens. Porcine Health Management, 4:31.}

Further Reading

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^{[1] Wallander C, Frössling J, Vågsholm I, Burrells A, Lundén A. (2015). “Meat juice” is not a homogeneous serological matrix. Foodborne Pathog Dis., 12:280–8}

^{[2] Meemken D, Tangemann AH, Meermeier D, Gundlach S, Mischok D, Greiner M, et al. (2014). Establishment of serological herd profiles for zoonoses and production diseases in pigs by “meat juice multi-serology”. Prev Vet Med, 113:589–98.}

^{[3] Mortensen S, Strandbygaard B, Bøtner A, Feld N, Willeberg P. (2001). Monitoring porcine reproductive and respiratory syndrome virus infection status in swine herds based on analysis of antibodies in meat juice samples. Vet Res, 32:441–53.}

^{[4] Molina RM, Chittick W, Nelson EA, Christopher-Hennings J, Rowland RR, Zimmerman JJ. (2008). Diagnostic performance of assays for the detection of anti-porcine reproductive and respiratory syndrome virus antibodies in serum and muscle transudate (“meat juice”) based on samples collected under experimental conditions. J Vet Diagn Investig, 20:735–43.}