Title DNA vaccine dual-expressing viral hemorrhagic septicemia virus glycoprotein and C-C motif chemokine ligand 19 induces the expression of immune-related genes in zebrafish (Danio rerio)
Author Jin-Young Kim1, Hyoung Jun Kim2, Jeong Su Park3, and Se Ryun Kwon3*
Address 1Department of Aqualife Medicine, Chonnam National University, Yeosu 59626, Republic of Korea, 2OIE Reference Laboratory for VHS, National Institute of Fisheries Science, Busan 46083, Republic of Korea, 3Department of Aquatic Life Medical Sciences, Sunmoon University, Asan 31460, Republic of Korea
Bibliography Journal of Microbiology, 60(10),1032-1038, 2022,
DOI 10.1007/s12275-022-2231-8
Key Words viral hemorrhagic septicemia virus (VHSV), DNA vaccine, chemokine ligand 19 (CCL19), molecular adjuvant, zebrafish (Danio rerio)
Abstract Glycoprotein (G protein)-based DNA vaccines are effective in protecting aquaculture fish from rhabdoviruses but the degree of immune response they elicit depends on plasmid concentration and antigen cassette. Here, we developed a DNA vaccine using the viral hemorrhagic septicemia virus G (VG) gene and chemokine (C-C motif) ligand 19 (CCL19)a.2 regulated by the CMV promoter as the molecular adjuvant. After transfection of the prepared plasmid (pVG + CCL19) into epithelioma papulosum cyprini cells, mRNA expression was confirmed through quantitative real-time polymerase chain reaction. The vaccine was intramuscularly injected into zebrafish (Danio rerio), and 28 days after immunization, viral hemorrhagic septicemia virus (105 TCID50/10 μl/fish) was intraperitoneally injected. A survival rate of 68% was observed in the pVG + CCL19 group but this was not significantly different from the survival rate of fish treated with pVG alone, that is, without the adjuvant. However, the expression of interferonand cytokine-related genes in the spleen and kidney tissues of zebrafish was significantly increased (p < 0.05) on days 1, 3, 7, and 14 after immunization. Thus, CCL19a.2 induced an initial immune response as a molecular adjuvant, which may provide initial protection against virus infection before vaccination- induced antibody formation. This study provides insights on the functions of CCL19a.2 adjuvant in DNA vaccines.