Evaluation of Flinders Technology Associates cards for collection and transport of samples for detection of Porcine reproductive and respiratory syndrome virus by reverse transcription polymerase chain reaction

Abstract

Blood, tissue and oral fluid samples collected from experimentally infected animals and field cases were used to evaluate the safety, diagnostic sensitivity and specificity of Flinders Technology Associates (FTA) cards for Porcine reproductive and respiratory syndrome virus (PRRSV) reverse transcription polymerase chain reaction (RT-PCR) diagnostics. The analytical sensitivity of PRRSV RT-PCR from serum and oral fluids in FTA cards was reduced, although the virus could still be detected at concentrations of 10(1) and 10(3) TCID/ml, respectively. The sensitivity and specificity of PRRSV RT-PCR detection from serum, blood, and tissue samples in cards collected from experimentally infected animals were 100%. Sensitivity for oral fluids was 45% (95% CI: 19.97-73.01) compared to fresh. For field samples, sensitivity was 89% (95% CI: 77.35-95.63) and 100% (95% CI: 80.00-100) for serum and lung samples, respectively. The sensitivity was the same for samples stored in cards at room temperature or at 4ºC, and tested overnight or after 14 days. Cards inoculated with PRRSV-positive samples did not yield replicating virus after cell culture. In conclusion, FTA cards proved to be a safe, simple, and sensitive alternative method to transport serum, blood, and tissue samples for PRRSV RT-PCR diagnostics; however, a significant decrease in RT-PCR sensitivity should be expected from oral fluid samples.