[Cloning and immunological characteristics of canine IL-18 cDNA]

To clone the canine IL-18 cDNA and to explore the immunological effectiveness of canine IL-18 as an adjuvant of genetic vaccine.

Canine leukocytes were separated from peripheral blood stimulated with ConA for 5-12 h. The full length cDNA of canine IL-18 was amplified by RT-PCR using leukocyte mRNA as a template. IL-18 cDNA was cloned into pMD18-T. Sequencing result showed that the full length cDNA was 582 bp, encoding 193 amino acids, which was identical with that published. The eukaryotic expression vector pIIL18 was constructed. Dogs were inoculated in mixture form of pIGneo and pIIL18.

Canine IL-18 cDNA was successfully cloned and eukaryotic expression vector pIIL18 was constructed. The immunological assay result showed that the anti-rabies virus-specific antibody level of the group immunized with mixture of pIIL18 and pIGneo was obviously lower than that of the group immunized with pIGneo alone, but the level of cellular immunity of the former was higher than the latter.

Canine IL-18 can enhance cellular immunity but at the same time suppress humoral immunity, which lays the foundation for IL-18 as an adjuvant of genetic vaccine.