The viruses Betaarterivirus suid 1 and Betaarterivirus suid 2 are recognized as the etiological agents of porcine reproductive and respiratory syndrome (PRRS), a condition that severely impacts swine health and inflicts major economic damage across leading pig-producing nations. In this study, we describe the establishment of an innovative RNA in situ hybridization method (RNAscope) tailored for the visualization of PRRS virus (PRRSV) RNA in the lung tissues of experimentally infected pigs. Lung samples from 20 piglets inoculated with a wild-type, highly virulent PRRSV-1 isolate were analyzed using this approach. To assess whether RNAscope could be used in a semi-quantitative manner, the proportion of infected cells determined by digital image analysis (QuPath) was compared with viral RNA levels measured by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) conducted on the same samples. A strong correspondence between both molecular results was observed (pseudo R² = 0.3894, p = 0.004). This study represents the first demonstration of RNAscope’s application for detecting PRRSV-1 in an experimental infection model.
