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The use of oral fluids to monitor key pathogens in porcine respiratory disease complex

View Article: PubMed Central - PubMed

ABSTRACT

Background: The usefulness of oral fluid (OF) sampling for surveillance of infections in pig populations is already accepted but its value as a tool to support investigations of porcine respiratory disease complex (PRDC) has been less well studied. This study set out to describe detection patterns of porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus type 2 (PCV2), swine influenza virus type A (SIV) and Mycoplasma hyopneumoniae (M. hyo) among farms showing differing severity of PRDC.

Background: The study included six wean-to-finish pig batches from farms with historical occurrence of respiratory disease. OF samples were collected from six pens every two weeks from the 5th to the 21st week of age and tested by real time PCR for presence of PRRSV, SIV and M. hyo and by quantitative real time PCR for PCV2. Data was evaluated alongside clinical and post-mortem observations, mortality rate, slaughter pathology, histopathology, and immunohistochemistry testing data for PCV2 antigen where available.

Results: PRRSV and M. hyo were detectable in OF but with inconsistency between pens at the same sampling time and within pens over sequential sampling times. Detection of SIV in clinical and subclinical cases showed good consistency between pens at the same sampling time point with detection possible for periods of 2–4 weeks. Quantitative testing of OF for PCV2 indicated different patterns and levels of detection between farms unaffected or affected by porcine circovirus diseases (PCVD). There was good correlation of PCR results for multiple samples collected from the same pen but no associations were found between prevalence of positive test results and pen location in the building or sex of pigs.

Conclusions: Detection patterns for PRRSV, SIV and M. hyo supported the effectiveness of OF testing as an additional tool for diagnostic investigation of PRDC but emphasised the importance of sampling from multiple pens and on multiple occasions. Preliminary evidence supported the measurement of PCV2 load in pooled OF as a tool for prediction of clinical or subclinical PCVD at farm level.

No MeSH data available.


PCV2 viral load for OF samples collected in the same pen. PCV2 viral load logarithmic values for pairs of OF samples collected from the same pens in the same time point. For each pen the rope with the highest and the lowest viral load were included. In BLACK, viral load over the limit of quantification for both ropes; as it has been not defined for OF, the authors considered the reference value for serum (1 × 104 genome copies/mL). In BLUE, PCV2 positive samples with at least one rope over the limit of detection (1 × 103.48 genome copies/mL) but under limit of quantification (1 × 104 genome copies/mL). In GREY, PCV2 viral load values under the limit of detection for at least one rope; note that viral load values under the limit of quantification could be not accurately quantified. There was a strong correlation (R2 = 0.97, p < 0.01) between viral load for pairs of ropes with PCV2 viral load over the limit of detection
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Fig7: PCV2 viral load for OF samples collected in the same pen. PCV2 viral load logarithmic values for pairs of OF samples collected from the same pens in the same time point. For each pen the rope with the highest and the lowest viral load were included. In BLACK, viral load over the limit of quantification for both ropes; as it has been not defined for OF, the authors considered the reference value for serum (1 × 104 genome copies/mL). In BLUE, PCV2 positive samples with at least one rope over the limit of detection (1 × 103.48 genome copies/mL) but under limit of quantification (1 × 104 genome copies/mL). In GREY, PCV2 viral load values under the limit of detection for at least one rope; note that viral load values under the limit of quantification could be not accurately quantified. There was a strong correlation (R2 = 0.97, p < 0.01) between viral load for pairs of ropes with PCV2 viral load over the limit of detection

Mentions: In those pens where multiple samples tested positive or weak positive (in the case of SIV or M. hyo), correlations between different samples Ct values were significant (P < 0.01) and strong (R2 ≥ 0.60) for every pathogen tested PCV2 (R2 = 0.97) (Fig. 7), PRRSV (R2 = 0.85), SIV (R2 = 0.79) and M. hyo (R2 = 0.60).Fig. 7


The use of oral fluids to monitor key pathogens in porcine respiratory disease complex
PCV2 viral load for OF samples collected in the same pen. PCV2 viral load logarithmic values for pairs of OF samples collected from the same pens in the same time point. For each pen the rope with the highest and the lowest viral load were included. In BLACK, viral load over the limit of quantification for both ropes; as it has been not defined for OF, the authors considered the reference value for serum (1 × 104 genome copies/mL). In BLUE, PCV2 positive samples with at least one rope over the limit of detection (1 × 103.48 genome copies/mL) but under limit of quantification (1 × 104 genome copies/mL). In GREY, PCV2 viral load values under the limit of detection for at least one rope; note that viral load values under the limit of quantification could be not accurately quantified. There was a strong correlation (R2 = 0.97, p < 0.01) between viral load for pairs of ropes with PCV2 viral load over the limit of detection
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5382517&req=5

Fig7: PCV2 viral load for OF samples collected in the same pen. PCV2 viral load logarithmic values for pairs of OF samples collected from the same pens in the same time point. For each pen the rope with the highest and the lowest viral load were included. In BLACK, viral load over the limit of quantification for both ropes; as it has been not defined for OF, the authors considered the reference value for serum (1 × 104 genome copies/mL). In BLUE, PCV2 positive samples with at least one rope over the limit of detection (1 × 103.48 genome copies/mL) but under limit of quantification (1 × 104 genome copies/mL). In GREY, PCV2 viral load values under the limit of detection for at least one rope; note that viral load values under the limit of quantification could be not accurately quantified. There was a strong correlation (R2 = 0.97, p < 0.01) between viral load for pairs of ropes with PCV2 viral load over the limit of detection
Mentions: In those pens where multiple samples tested positive or weak positive (in the case of SIV or M. hyo), correlations between different samples Ct values were significant (P < 0.01) and strong (R2 ≥ 0.60) for every pathogen tested PCV2 (R2 = 0.97) (Fig. 7), PRRSV (R2 = 0.85), SIV (R2 = 0.79) and M. hyo (R2 = 0.60).Fig. 7

View Article: PubMed Central - PubMed

ABSTRACT

Background: The usefulness of oral fluid (OF) sampling for surveillance of infections in pig populations is already accepted but its value as a tool to support investigations of porcine respiratory disease complex (PRDC) has been less well studied. This study set out to describe detection patterns of porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus type 2 (PCV2), swine influenza virus type A (SIV) and Mycoplasma hyopneumoniae (M. hyo) among farms showing differing severity of PRDC.

Background: The study included six wean-to-finish pig batches from farms with historical occurrence of respiratory disease. OF samples were collected from six pens every two weeks from the 5th to the 21st week of age and tested by real time PCR for presence of PRRSV, SIV and M. hyo and by quantitative real time PCR for PCV2. Data was evaluated alongside clinical and post-mortem observations, mortality rate, slaughter pathology, histopathology, and immunohistochemistry testing data for PCV2 antigen where available.

Results: PRRSV and M. hyo were detectable in OF but with inconsistency between pens at the same sampling time and within pens over sequential sampling times. Detection of SIV in clinical and subclinical cases showed good consistency between pens at the same sampling time point with detection possible for periods of 2&ndash;4 weeks. Quantitative testing of OF for PCV2 indicated different patterns and levels of detection between farms unaffected or affected by porcine circovirus diseases (PCVD). There was good correlation of PCR results for multiple samples collected from the same pen but no associations were found between prevalence of positive test results and pen location in the building or sex of pigs.

Conclusions: Detection patterns for PRRSV, SIV and M. hyo supported the effectiveness of OF testing as an additional tool for diagnostic investigation of PRDC but emphasised the importance of sampling from multiple pens and on multiple occasions. Preliminary evidence supported the measurement of PCV2 load in pooled OF as a tool for prediction of clinical or subclinical PCVD at farm level.

No MeSH data available.