Fish immunization using a synthetic double-stranded RNA Poly(I:C), an interferon inducer, offers protection against RGNNV, a fish nodavirus

• Published in: Diseases of aquatic organisms Vol. 83; no. 2; pp. 115 - 122
• Main Authors: NISHIZAWA, Toyohiko, TAKAMI, Ikuo, KOKAWA, Yuki, YOSHIMIZU, Mamoru
• Format: Journal Article
• Language: English
• Published: Oldendorf Inter-Research 12.02.2009
• Subjects: Animal aquaculture; Animal productions; Animals; Antibodies, Viral - blood; Biological and medical sciences; Fish Diseases - immunology; Fish Diseases - prevention & control; Fish Diseases - virology; Fundamental and applied biological sciences. Psychology; Interferon Inducers - immunology; Nodaviridae - immunology; Perciformes; Pisciculture; Poly I-C - immunology; RNA Virus Infections - immunology; RNA Virus Infections - veterinary; RNA Virus Infections - virology; RNA, Double-Stranded - immunology; Specific Pathogen-Free Organisms; Time Factors; Vertebrate aquaculture; Fish nodavirus; Immunization; Double stranded RNA; Antiviral state; Poly(I:C); Viral nervous necrosis; Vaccine; Sevenband grouper; Necrosis; Virus; Vertebrata; Pisces; Nodaviridae; Interferon inducer; VNN; Antiviral; Protection; Nodavirus
• ISSN: 0177-5103; 1616-1580
• DOI: 10.3354/dao02001

Viral nervous necrosis (VNN), caused by a fish nodavirus, is one of the most serious fish diseases worldwide. Here we report a unique vaccination method in sevenband grouper Epinephelus septemfasciatus using a synthetic double-stranded RNA polyinosinic polycytidylic acid (Poly(I:C)), an interferon inducer, followed by challenge with a live fish nodavirus. Fish injected with Poly(I:C) at 200 microg fish(-1) were highly protected from artificial challenge with red-spotted grouper nervous necrosis virus (RGNNV) (relative percentage survival, RPS: 100%), and specific antibodies against RGNNV were detected in sera from survivors. Moreover, the surviving fish were protected from rechallenge with RGNNV (relative percent survival RPS: 100%). Thus, it was confirmed that specific immunity against RGNNV was established in sevenband grouper by injection with live RGNNV following Poly(I:C) administration. Antiviral state was induced in fish by injection with Poly(I:C) at > or = 50 microg fish(-1), but no toxic response was observed in the fish even if Poly(I:C) was injected at a dose of 200 microg fish . In fish injected with Poly(I:C) at 200 pg fish(-1), a high level of antiviral state of > 90% RPS against RGNNV challenge lasted for at least 4 d after Poly(I:C) injection. However, no curative effect by Poly(I:C) injection was observed in fish already infected with RGNNV. It is considered that the present immunization method using Poly(I:C) followed by a live virus injection could offer protection against various viral infections in a broader range of fish species.