Construction of an Expression System for Bioactive IL-18 and Generation of Recombinant Canine Distemper Virus Expressing IL-18

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.

Imbalanced production of IL-18 and its antagonist in human diseases, and its implications for HIV-1 infection

“…To utilize IL-18 as an adjuvant in vaccination attempts, IL-18 gene has been included in expression vectors along with the gene for an antigen. The vectors induce higher antigen specific humoral and cellular responses [57].…”

Rescue of recombinant canine distemper virus that expresses S1 subunit of SARS-CoV-2 spike protein in vitro

“…This prompted us to develop a CDV-vectored candidate against SARS-CoV-2 infection in animals. CDV is an ideal vector to encode foreign proteins, such as fluorescence proteins [ 20 , 21 ], luciferases [ 13 , 22 ] and interleukins [ 23 , 24 ]. CDV additionally exhibits specific properties with potential applications in developing multivalent vaccines against canine distemper and other diseases [ [25] , [26] , [27] ].…”

Recovery of NanoLuc Luciferase-Tagged Canine Distemper Virus for Facilitating Rapid Screening of Antivirals in vitro

“…The reverse genetics system for CDV had been established as early as 2000 ( 20 ). CDV is an ideal vector for expressing various foreign proteins, including green fluorescence protein (GFP) ( 21 ), red fluorescence protein ( 22 ), firefly luciferase ( 10 ), interleukin-7 ( 23 ), interleukin-18 ( 24 ), and rabies virus glycoprotein ( 25 ). The NLuc is a novel luciferase that has many physical properties, making it an excellent reporter protein ( 26 ).…”