Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Biology and Microbiology


The sensitivity and specificity of the virus neutralization (VN) and indirect immunofluorescence (IF A) tests for the detection of antibodies to porcine reproductive and respiratory syndrome virus (PRRSV) was compared using 1,605 field sera from pigs with reproductive and/or respiratory disease. In the VN test, sera were diluted 2-fold (1:4 to 1:512); incubated with an equal volume of 100 TCID50 of PRRSV (ATCC VR-2332); and then the mixtures were added to duplicate wells of CL2621 cells. The VN titer was determined to be the highest dilution of sera which blocked cytopathic effects in CL262 l cells. In the IF A, CL2621 cells in 96-well microtiter plates were inoculated with PRRSV and cells were fixed 24 h later with 80% acetone. Sera were diluted 4-fold (1 :5 to 1:5, 120), each dilution was added to duplicate wells of inoculated and uninoculated CL262 l cells, and the sera containing antibodies were detected using FITC-labeled rabbit anti-swine IgG. Fifty percent (69/139) of the herds tested had animals with antibodies to VR-2332 by both VN and IFA. Thirty-two and 3% of all sera were positive by IF A and VN, respectively. Seven percent of all samples were positive by both assays; 58% were negative by both assays; and 8% (27/326) of the samples had antibody to both the European and North American isolates of PRRSV. Thirty-eight percent (297/776) of the samples from sows and gilts and 7% (9/129) of boars tested positive by VN and IPA Nineteen percent (96/501) of the breeding and 6% (15/260) of the finishing pigs were positive for PRRSV antibodies. In herds with 3 7 to 100 animals, 42% (16/38) tested positive, while 44% (24/54) of herds with more than 200 pigs were positive by VN and IF A Specificities of VN and IF A were calculated to be 97% and 86%, and sensitivities were 25% and 44%, respectively. Statistically, the IFA was significantly more effective than VN in detecting PRRSV antibodies.

Library of Congress Subject Headings

Swine -- Virus diseases -- Diagnosis


Porcine reproductive and respiratory syndrome



Number of Pages



South Dakota State University