Submitted to: American Association of Veterinary Laboratory Diagnosticians
Publication Type: Proceedings
Publication Acceptance Date: October 7, 1999
Publication Date: N/A
Technical Abstract: Porcine reproductive and respiratory syndrome (PRRS) is a disease of swine caused by the PRRS virus (PRRSV). PRRS was first recognized in 1987 and since then it has become the number one infectious disease problem for the swine industry. It causes acute reproductive failure in sows (abortions, stillborn and weak-born pigs) and respiratory disease in young pigs. Detecting the virus in serum or tissues of affected swine can be difficult resulting in a misdiagnosis of the disease. This paper describes efforts to evaluate different methods used by state diagnostic laboratories to detect PRRSV in swine with the anticipated goal of identifying a particular method that may be superior and could be used by all laboratories. Overall, serum may be the best specimen to test because 1) experimental work has consistently demonstrated PRRSV can circulate in the blood of infected swine for extended periods of time and 2) the relative ease with which blood can be collected. Matched sets of pig serum that did or did not contain PRRSV were mailed to 12 laboratories that routinely test for PRRSV; 7 of the laboratories only used virus isolation (VI) to test for whole virus, and the remaining 5 laboratories used VI and PCR (a test to detect PRRSV genetic material) for detection of serum PRRSV. The most successful VI technique utilized about 0.5 ml of serum adsorbed onto a 25 cm**2 monolayer of MARC-145 cells. The cell culture was passaged 3 times before determining if the serum was VI negative. The most successful PCR techniques utilized a nested set of primers for ORF 5 and ORF 7 of the virus.