DAO 56:43-48 (2003)  -  doi:10.3354/dao056043

CpG motif in synthetic ODN primes respiratory burst of olive flounder Paralichthys olivaceus phagocytes and enhances protection against Edwardsiella tarda

Chan Hwei Lee1, Hyun Do Jeong1, Joon Ki Chung1, Hyung Ho Lee2, Ki Hong Kim1,*

1Department of Aquatic Life Medicine, Pukyong National University, Pusan 608-737, South Korea
2Faculty of Food Science and Biotechnology, Pukyong National University, Pusan 608-737, South Korea
*Corresponding author. Email:

ABSTRACT: Effects of synthetic cytidine-phosphate-guanosine (CpG) oligodeoxynucleotide (ODN) on respiratory burst activity of olive flounder (Paralichthys olivaceus) head-kidney phagocytes and on protection against lethal infection with Edwardsiella tarda were investigated. Phagocytes precultured with a CpG ODN showed significantly higher chemiluminescence (CL) responses than phagocytes precultured with guanosine-phosphate-cytidine (GpC) ODN or culture medium alone (control) at all concentrations. Supernatants produced from leucocytes, which were pulsed with CpG ODN, induced significantly higher respiratory burst activity than supernatants produced by GpC ODN or culture medium alone. In an in vivo experiment, respiratory burst activities of the head kidney phagocytes in the groups injected either 0.25 or 0.5 µg fish-1 of CpG ODN were significantly higher than those in the groups injected with GpC ODN or HBSS (control) at 3, 5 and 7 d after injection. The groups of fish injected with 0.25 or 0.5 µg of CpG ODN showed higher survival rates (83.3%) than groups treated with GpC ODN (33.3%) and a control group (8.3%) after challenge with E. tarda. The present in vitro and in vivo experiments have demonstrated the ability of synthetic CpG ODN to increase phagocyte respiratory burst activity and disease resistance in olive flounder.

KEY WORDS: Synthetic CpG ODN · Olive flounder · Respiratory burst · Phagocytes · Disease resistance · Edwardsiella tarda

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