Protection of Japanese flounder Paralichthys olivaceus from viral hemorrhagic septicemia (VHS) by Poly(I:C) immunization.

Abstract

In immunization of fish with polyinosinic-polycytidylic acid (poly[I:C], a synthetic double-stranded RNA, injection of Poly(I:C) followed by challenge with a live virus induces a transient, non-specific antiviral state by interferon activity. When exposed to a virus while in this antiviral state, the fish acquire a specific and protective immunity against the corresponding viral disease and survive. In the present study, the effiacy of Poly(I:C) immunization was investigated in japanese flounder Paralichthys olivaceus using viral hemorrhagic septicemia virus (VHSV) as a model; the minimum dose of Poly(I:C) required for inducing protection and the duration of the antiviral state were determined, and a potentially curative effect of Poly(I:C) administration was assessed. The antiviral state was induced by administration of Poly(I:C) doses ranging from 12.5 to 200 microg fish(-1). Minimum dose to induce the antiviral state (relative percentage survival, RPS: 90%) was 12.5 microg fish(-1). No curative effect of Poly(I:C) was observed in fish pre-infected with VHSV. Fish injected with 200 microg Poly(I:C) fish(-1) were highly protected (RPS: 100%) from an artificial challenge with VHSV, and specific antibodies against VHSV were detected. The corresponding high level of antiviral state against VHSV was attained 1 d post Poly(I:C) injection, lasted for 6 d and susequently decreased. Moreover, the surviving fish were highly protected from re-challenge with VHSV (RPS: 100%). Thus, it was considered that an immunity against viral hemorrhagic septicemia was induced in the Japanese flounder by injecting live VHSV following Poly(I:C) administration.

• Authors: Ikuo Takami, Se Ryun Kwon, Toyohiko Nishizawa, Mamoru Yoshimizu
• Journal: Diseases of aquatic organisms (Dis Aquat Organ) Vol. 89 Issue 2 Pg. 109-15 (Mar 09 2010) ISSN: 0177-5103 [Print] Germany
• PMID: 20402228 (Publication Type: Controlled Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Viral Vaccines
• Poly I-C

Topics

• Animals
• Flounder
• Hemorrhagic Septicemia, Viral (prevention & control, virology)
• Poly I-C (immunology)
• Viral Vaccines (immunology)