Comparison of the recovery of PCR-detectable porcine epidemic diarrhea virus and porcine reproductive and respiratory syndrome virus from filter papers under laboratory conditions

TL;DR

This study compares how well different filter papers recover viral RNA under lab conditions, showing that paper type and elution methods impact detection efficiency.

Contribution

The study introduces a systematic comparison of filter paper types and elution conditions for recovering two swine viruses, providing insights into optimal sampling methods.

Findings

Paper products 3 and 4 released the highest volumes of liquid in Experiment 1.

Elution buffer, paper type, and virus dilution significantly affected RNA recovery in Experiment 2.

Certain paper types and lysis buffer achieved RNA detection levels comparable to positive controls.

Abstract

The need for cost effective surveillance of emerging human and veterinary pathogens has triggered a resurgence in research on environmental sampling methods, a process in which filter paper could play a role. The objective of this research was to compare the recovery of nucleic acids from paper products under laboratory conditions.

In Experiment 1, commercially available paper products (n = 9) were saturated with water (1000 to 3000 µl) and the volume of decanted liquid measured and analyzed (linear regression). In Experiment 2, 4 paper products from Experiment 1 were evaluated for the release of RT-qPCR-detectable porcine reproductive and respiratory syndrome virus (PRRSV) RNA and porcine epidemic diarrhea virus (PEDV) RNA. Specifically, products were inoculated with PRRSV and PEDV, dried, subjected to 9 elution conditions (3 elution buffers × 3 soaking times), and tested by RT-qPCR. Thereafter, results were normalized and re-expressed as efficiency-standardized Cqs (ECqs).

In Experiment 1, significant differences in recovery were observed across products and volumes (p < 0.05), with paper products 3 and 4 releasing the highest volumes. In Experiment 2, linear regression analysis showed that paper type, elution buffer, virus dilution, and their interactions affected viral RNA recovery (p < 0.05). AUC analysis showed no significant difference in PRRSV RNA detection between buffer-specific positive controls and product 3 eluted with lysis buffer or water. Similarly, no difference was detected in PEDV RNA detection between the positive control eluted with lysis buffer and products 3 and 4 eluted with lysis buffer. These results demonstrated that the choice of filter paper and the procedures used for viral RNA detection significantly affect target recovery.

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