The Efficacy of Inactivated Virus Vaccine against Viral Nervous Necrosis (VNN)

Abstract

ABSTRACT-The efficacy of inactivated betanodavirus as a vaccine against viral nervous necrosis (VNN) was evaluated using juvenile sevenband grouper Epinephelus septemfasciatus.Fish were intraperitoneally injected once with formalin-inactivated redspotted grouper nervous necrosis virus (RGNNV). Virus-neutralizing antibodies were detected in the vaccinated fish from Day 10 to the end of the experimental period (Day 160), showing 1: 2,000 or higher mean antibody titers from Day 21 to Day 77. The vaccinated and unvaccinated control fish were challenged by intramuscular injection with the homologous virus at 14, 35 and 74 days post-vaccination.The vaccinated fish showed significantly lower mortalities at any challenges than the control fish, with the RPS (relative percent survival) values 67 or higher. A field trial, in which fish were exposed to natural infection in net pens, also resulted in higher survival rates in the vaccinated fish (RPS = 85) during the experi mental period of 9 weeks. This high induction of neutralizing antibodies and protection indicates the potential of the inactivated virus vaccine against VNN.

Aquabirnavirus-induced Protection of Marine Fish against Piscine Nodavirus Infection

“…vaccination system. The previous vaccination studies revealed that the recombinant coat protein or formalin-inactivated virus induced high and long duration of virus-neutralizing anti bodies and protection against virus challenges (Husgard et al, 2001;Tanaka et al, 2001;Yamashita et al, 2005). However, it takes 2 or more weeks to the onset of specific immunity against nodaviruses and thus there is a room for vaccine improvement.…”

“…However, there are no means to prevent the disease in older fish during net-pen culture, though the protective effects of the recombinant coat protein or inactivated virus vaccines were experimentally demonstrated (Tanaka et al, 2001;Yamashita et al, 2005).…”

Cell Culture Isolation of Piscine Nodavirus (Betanodavirus) in Fish-Rearing Seawater

“…A betanodavirus SGEhi00 strain, which had been isolated from a diseased sevenband grouper in Japan and identified as RGNNV (31), was used in this study. The virus was propagated in E-11 cells cultured at 25°C in Leibovitz's L-15 medium (Life Technologies, USA) supplemented with 5% fetal bovine serum (FBS), as previously described (32).…”

Betanodavirus of Marine and Freshwater Fish: Distribution, Genomic Organization, Diagnosis and Control Measures

“…To ensure that the fish are as healthy as possible, a useful and practical approach would be vaccination of fish and boosting their immune system. Various types of vaccines have been developed such as formalininactivated vaccine, subunit vaccine with recombinant coat protein of betanodavirus and nodavirus-like particle vaccine [58,74,111,116,118,121,124]. Vaccination trials have shown protection efficacy against betanodavirus infection.…”