Construction of an expression system for bioactive IL-18 and generation of recombinant canine distemper virus expressing IL-18

J Vet Med Sci. 2014 Sep;76(9):1241-8. doi: 10.1292/jvms.14-0181. Epub 2014 Jun 4.

Abstract

Interleukin 18 (IL-18) plays an important role in the T-helper-cell type 1 immune response against intracellular parasites, bacteria and viral infections. It has been widely used as an adjuvant for vaccines and as an anticancer agent. However, IL-18 protein lacks a typical signal sequence and requires cleavage into its mature active form by caspase 1. In this study, we constructed mammalian expression vectors carrying cDNA encoding mature canine IL-18 (cIL-18) or mouse IL-18 (mIL-18) fused to the human IL-2 (hIL-2) signal sequence. The expressed proIL-18 proteins were processed to their mature forms in the cells. The supernatants of cells transfected with these plasmids induced high interferon-γ production in canine peripheral blood mononuclear cells or mouse splenocytes, respectively, indicating the secretion of bioactive IL-18. Using reverse genetics, we also generated a recombinant canine distemper virus that expresses cIL-18 or mIL-18 fused to the hIL-2 signal sequence. As expected, both recombinant viruses produced mature IL-18 in the infected cells, which secreted bioactive IL-18. These results indicate that the signal sequence from hIL-2 is suitable for the secretion of mature IL-18. These recombinant viruses can also potentially be used as immunoadjuvants and agents for anticancer therapies in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Assay
  • Distemper / immunology*
  • Distemper / prevention & control
  • Distemper Virus, Canine / genetics
  • Distemper Virus, Canine / immunology*
  • Dogs
  • Genetic Vectors / genetics
  • Genetic Vectors / immunology
  • Humans
  • Immunoblotting
  • Interleukin-18 / genetics
  • Interleukin-18 / immunology*
  • Interleukin-2 / genetics
  • Interleukin-2 / immunology
  • Leukocytes, Mononuclear
  • Mice
  • Plasmids / genetics
  • Plasmids / immunology
  • RNA / chemistry
  • RNA / genetics
  • Reverse Transcriptase Polymerase Chain Reaction
  • Vaccines, Synthetic / genetics
  • Vaccines, Synthetic / immunology*
  • Viral Vaccines / genetics
  • Viral Vaccines / immunology*

Substances

  • Interleukin-18
  • Interleukin-2
  • Vaccines, Synthetic
  • Viral Vaccines
  • RNA