Cytokines and synthetic double-stranded RNA augment the T helper 1 immune response of swine to porcine reproductive and respiratory syndrome virus.
Immunization of pigs with a modified live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine initially elicits a weak interferon (IFN)-gamma response. To improve the immune response, an adjuvant consisting of plasmid encoding either porcine interleukin (IL)-12 or IFN-alpha was co-administered during vaccination. In the presence of either adjuvant, at least a three-fold increase in the primary virus-specific IFN-gamma response was observed. While this enhancement was only transient (1 week) when the IL-12 expressing plasmid was used, the effect was not only still apparent at 6 weeks after vaccination in the presence of the IFN-alpha expressing plasmid but even after challenge with a virulent genetically divergent PRRSV. In contrast, no effect of either adjuvant on the production of anti-virus antibodies was noticed throughout the study. Despite the apparent augmentation of a T helper (Th) 1 type response by the inclusion of IFN-alpha or IL-12 during vaccination, this modulation did not necessarily correlate with a reduction in viremia. Since a similar increase in the degree of the IFN-gamma response to the PRRSV vaccine could be achieved by substituting polyinosinic-polycytidylic acid in lieu of either cytokine, exposure to PRRSV in the presence of a variety of Th 1 polarizing molecules can positively influence the development of the cell-mediated immune response of swine to this pathogen. Conceivably, such intervention could be applied to improve the formulation of anti-PRRSV vaccines.
Meier
William A
WA
Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Illinois, Urbana, IL 61802, USA.
Husmann
Robert J
RJ
Schnitzlein
William M
WM
Osorio
Fernando A
FA
Lunney
Joan K
JK
Zuckermann
Federico A
FA
D000818:Animals; D016898:Interferon-alpha / Q000276:immunology*; D018664:Interleukin-12 / Q000276:immunology*; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000276:immunology*; D012330:RNA, Double-Stranded / Q000276:immunology*; D013552:Swine / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology*; D013997:Time Factors; D014765:Viral Vaccines / Q000276:immunology
D016898:Interferon-alpha; D012330:RNA, Double-Stranded; D014765:Viral Vaccines; D018664:Interleukin-12