HUMORAL AND CELLULAR IMMUNE RESPONSES OF SWINE TO PLASMID DNA ENCODING THE PRRS VIRUS ORFS 4, 5, 6, AND 7

Authors: Kwang, Hwei Sing; ZUCKERMANN, F - UNIVERSITY OF ILLINOIS; Ross, Gary; Yang, Xiao; JOO, H - UNIVERISTY OF MINNESOTA; OSORIO, FERNANDO - UNIVERSITY OF NEBRASKA; Laegreid, William

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: For this study, the genomic regions of vaccine strain of the PRRS virus (NOBL Laboratories) encoding ORFs 4, 5, 6, and 7 were cloned into the mammalian expression vector pcDNA3 (Invitrogen). The appropriate orientation and functionality of each recombinant construct was verified by: sequencing and expression of PRRS virus protein in MARC-145 cells transfected with recombinant plasmids. Twenty PRRS virus-free newborn piglets were divided into 5 groups (4 piglets per group). At 3 weeks of age, each group (except 1 group receiving pcDNA3 plasmid only) received recombinant plasmid DNA doses of 400 ug by intramuscular and intra-dermal injection every 3 weeks for a total of 4 inoculations. Two pigs (1 in ORF 4 and 1 in ORF 5 groups) were removed from the study because of musculoskeletal problems leaving 14 PRRS virus-recombinant DNA vaccinates. Sera and peripheral blood lymphocytes were collected from all 18 pigs to study their immune response. Inoculation with the recombinant plasmids resulted in a PRRS virus-specific humoral (ELISA titers and/or Western blotting activity) and cellular (interferon gamma-producing cells) immune response in 7/14 and 9/14 of the immunized pigs, respectively. Pigs in the control group had no detectable immunity to PRRS virus. Virus neutralizing activity was detected in 2/3 ORF-4 and 1/3 ORF-5 immune pigs. These results suggest that neutralization epitopes for PRRS virus appear to reside in the viral envelope glycoproteins encoded by ORF 4 and ORF 5, and that both