SWINE VIRAL DISEASES PATHOGENESIS AND IMMUNOLOGY
Location: Virus and Prion Research Unit
Title: Development of a replication defective adenovirus 5 vector expressing porcine interleukin-18 and a mutated analog
Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: December 7, 2008
Publication Date: December 7, 2008
Citation: Kappes, M.A., Ma, W., Richt, J.A., Lager, K.M., Vincent, A.L., Roth, J.A., Murtaugh, M.P., Kehrli, Jr., M.E. 2008. Development of a Replication Defective Adenovirus 5 Vector Expressing Porcine Interleukin-18 and a Mutated Analog [abstract]. Conference of Research Workers in Animal Diseases. Paper No. 99P. p. 121.
Cell-mediated immune responses against swine pathogens are sometimes necessary to elicit durable protective immunity. Cell mediated or Th1 immunity is dependent on the coordinated expression of several cytokines, including interferon-gamma to assist in the production of antigen-specific cytotoxic T cells. Neonatal and stressed animals are known to have an impaired capacity to produce interferon-gamma which may bias their immune response to antigens towards a humoral response and diminish the initial development of a cell-mediated immune response. Interleukin-18 is a potent pleiotropic cytokine that enhances the production of interferon-gamma enhances natural killer cell cytotoxicity and stimulates Th1 cell differentiation. In an effort to develop a means of enhancing Th1 immune responses in swine, we chose to incorporate porcine interleukin-18 (IL-18) into a replication defective adenovirus expression system that has previously proven successful to deliver interferon-alpha or swine influenza antigens to pigs. Here we report development of a replication defective adenovirus 5 vector expressing wild-type porcine interleukin-18 or a mutated analog that possesses a double mutation at amino acid positions 42 and 89 (E42A plus K89A). With human IL-18, this double mutation results in a loss of binding by the regulatory IL-18 binding protein (IL-18BP), resulting in a 4-fold increase in activity of the mutant IL-18. Recombinant IL-18 (up to 1 ng/mL) was detected by ELISA in freeze/thawed supernatants of 2 wild-type IL-18 constructs and 8 mutated IL-18 constructs grown in AD-293 cell cultures; this cell line is used to propagate replication defective adenovirus vectors. Biological activity of each IL-18 construct was confirmed by the ability of these supernatants to induce interferon-gamma in porcine peripheral blood mononuclear cell cultures.