Cytokines and synthetic double-stranded RNA augment the T helper 1 immune response of swine to porcine reproductive and respiratory syndrome virus

Authors

• William A. Meier, University of Illinois, Urbana, IL
• Robert J. Husmann, University of Illinois, Urbana, IL
• William M. Schnitzlein, University of Illinois, Urbana, IL
• Fernando A. Osorio, University of Nebraska - LincolnFollow
• Joan K. Lunney, Animal Parasitic Disease Laboratory, ANRI, BARC, ARS, USDA, Beltsville, MD
• Federico A. Zuckermann, University of Illinois, Urbana, IL

Document Type

Article

Date of this Version

October 2004

Comments

Published in Veterinary Immunology and Immunopathology 102 (2004) 299–314.

Abstract

Immunization of pigs with a modified live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine initially elicits a weak interferon (IFN)-γ response. To improve the immune response, an adjuvant consisting of plasmid encoding either porcine interleukin (IL)-12 or IFN-α was co-administered during vaccination. In the presence of either adjuvant, at least a threefold increase in the primary virus-specific IFN-γ 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-α 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-α 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-γ 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.