porcine reproductive and respiratory syndrome virus, enveloped
P orcine reproductive and respiratory syndrome (PRRS), formerly called swine infertility and respiratory syn-. drome and mystery swine disease, is a recently de-. scribed viral disease of swine that is found in many parts. of the world.1-5 PRRS is caused by an enveloped RNA virus, approximately 62 nm in diameter, which is sensitive to lipid.