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

• Published in: Veterinary immunology and immunopathology Vol. 102; no. 3; pp. 299 - 314
• Main Authors: Meier, William A., Husmann, Robert J., Schnitzlein, William M., Osorio, Fernando A., Lunney, Joan K., Zuckermann, Federico A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 08.12.2004
• Subjects: Animals; Cellular immunity; cytokines; DNA vaccines; double-stranded RNA; immune response; immunization; Interferon-alpha - immunology; Interferon-α; Interferon-γ; interferons; Interleukin-12; Interleukin-12 - immunology; plasmids; porcine reproductive and respiratory syndrome; Porcine Reproductive and Respiratory Syndrome - immunology; Porcine Reproductive and Respiratory Syndrome - virology; Porcine reproductive and respiratory syndrome virus; Porcine respiratory and reproductive syndrome virus; Porcine respiratory and reproductive syndrome virus - immunology; PRRS virus; RNA, Double-Stranded - immunology; strain differences; strains; Swine; Swine - immunology; T-lymphocytes; Th1 Cells - immunology; Time Factors; vaccine adjuvants; Viral Vaccines - immunology; virulence; IL; poly I:C; Interleukin-12; Cellular immunity; PBMC; PRRS virus; IFN; SC; pcPIL12; Interferon-α; Th; Interferon-γ; Swine; MLV; pINA; VN; CMI; PRRSV
• ISSN: 0165-2427; 1873-2534
• DOI: 10.1016/j.vetimm.2004.09.012

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 three-fold 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.