title: Live vaccine of viral hemorrhagic septicemia virus (VHSV) for Japanese flounder at fish rearing temperature of 21°C instead of Poly(I:C) administration.
abstract: The process of "Poly(I:C) immunization" involves immunization of fish with a pathogenic live virus, followed by administration of Poly(I:C), which induces a transient, non-specific antiviral state. As a result, fish in an antiviral state survive the initial immunization with live virus. Moreover, these fish are able to mount a specific protective immune response against the injected pathogenic virus. In the present study, we investigated the optimum temperature for Poly(I:C) immunization of Japanese flounder Paralichthys olivaceus with live viral hemorrhagic septicemia virus (VHSV). It was revealed that the optimum temperature was around at 17°C for Poly(I:C) immunization in Japanese flounder. Furthermore, the protection efficacy of Poly(I:C) immunization was significantly decreased by elevation of fish rearing temperature, and no efficacy was observed at a fish rearing temperature of 25°C. Interestingly, no mortality by VHSV infection was observed in fish reared at 21°C and 25°C even when those fish were not administered Poly(I:C). All of the survivors from the first VHSV-challenge at 21°C were strongly protected from re-challenge with VHSV. However, almost all of the survivors (≥82.6%) from the first challenge at 25°C were lost by the second challenge with VHSV. It was thus concluded that by rearing fish at 21°C and challenging with live VHSV, it is possible to induce strong specific immunity in Japanese flounder without Poly(I:C) administration.
authors.affiliation: Department of Aqualife Medicine, Chonnam National University, Yeosu, Republic of Korea. jjnishi@chonnam.ac.kr
authors.forename: Toyohiko
authors.initials: T
authors.lastname: Nishizawa
authors.forename: Ikuo
authors.initials: I
authors.lastname: Takami
authors.forename: Minji
authors.initials: M
authors.lastname: Yang
authors.forename: Myung-Joo
authors.initials: MJ
authors.lastname: Oh
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000818:Animals; D005393:Fish Diseases / Q000276:immunology / Q000517:prevention & control*; D005412:Flatfishes; D029141:Novirhabdovirus / Q000276:immunology*; D011070:Poly I-C / Q000008:administration & dosage; D018353:Rhabdoviridae Infections / Q000517:prevention & control / Q000662:veterinary*; D016019:Survival Analysis; D013696:Temperature; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D014613:Vaccines, Attenuated; D014765:Viral Vaccines; D011070:Poly I-C