ESTABLISHMENT OF A REAL-TIME DETECTION METHOD FOR PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS USING A SURFACE-ENHANCED RAMAN SCATTERING SYSTEM

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major swine pathogen for which rapid, field-adaptable screening tools are needed. This study established complementary quantitative real-time polymerase chain reaction (qPCR) and surface-enhanced Raman scattering (SERS) workflows for PRRSV detection in swine specimens. Matrix-specific SERS preprocessing procedures were developed for serum, feces, and oral swabs, and a TaqMan-based qPCR standard operating procedure was used as the reference method. Serial PRRSV preparations from 8.152 to 2.152 log₁₀ copies/mL were evaluated by applying 2 µL of each processed sample to a SERS chip and measuring the spectra with a portable 785-nm Raman system. Detectable PRRSV preparations consistently exhibited seven characteristic peaks at approximately 832, 1,032, 1,154, 1,276, 1,374, 1,502, and 1,604 cm⁻¹. The SERS detection limit was 3.152 log₁₀ copies/mL (approximately 1.42 × 10³ copies/mL), whereas the qPCR detection limit was 14.2 copies/mL. A total of 50 field specimens, including 20 blood-derived serum samples, 20 fecal samples, and 10 oral swabs, were tested. The qPCR identified 10 positive and 40 negative specimens. SERS correctly identified 9 of the 10 qPCR-positive specimens and all 40 qPCR-negative specimens. The single false-negative specimen contained 125.3 copies/mL, below the SERS analytical detection limit. Using qPCR as the reference, the preliminary sensitivity and specificity of SERS were 90% and 100%, respectively. These findings support SERS as a rapid screening platform for PRRSV, particularly when viral loads exceed the analytical detection limit; molecular confirmation remains advisable for negative specimens with suspected low viral loads.