SERUM IMMUNE-RESPONSES TO THE PROTEINS OF PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME (PRRS) VIRUS

The antibody responses of pigs to porcine reproductive and respiratory syndrome virus (isolate VR-2332) were evaluated by indirect immunoflu orescence, virus neutralization, and immunoblotting. All pigs in each group were positive by indirect immunofluorescence 14-21 days postexpo sure (DPE), and antibodies to specific viral proteins (15, 19 or 26 kD ) were initially demonstrated by immunoblotting at 7-21 days DPE. Neut ralizing antibodies were detected in only 2 pigs that were inoculated intranasally and given additional parenteral injections with adjuvant. These antibodies appeared much later, 51-70 DPE, than did antibodies detected by indirect immunofluorescence. The titer of the neutralizing antibodies increased until 127 DPE, after which the titers decreased, and 1 animal became seronegative for neutralizing antibody by 262 DPE .