Selection of brood stock candidates of barfin flounder using an ELISA system with recombinant protein of barfin flounder nervous necrosis virus

Abstract

Barfin flounder nervous necrosis virus (BFNNV), the causative agent of viral nervous necrosis (VNN) of barfin flounder, is vertically transmitted from spawners to larvae. In the present study, an ELISA with a recombinant protein of BFNNV was performed for the detection of antibodies against BFNNV and applied for the selection of brood fish in order to prevent viral vertical transmissions. Brood stocks were divided into 4 groups based on ELISA antibody titers (<10, 20, 40 and >40), and the BFNNV status of the brood stocks was determined by PCR. BFNNV was detected from the brood fish in the group with an antibody titer of >40 but not from those with titers 210, 20 and 40. The offspring obtained from PCRnegative brood fish pairs in each group of ELISA antibody titers were subsequently reared for observation of VNN occurrence. VNN occurred in juveniles from 2 of 9 pairs of spawners with an antibody titer 240, but did not occur in spawners with an antibody titer of 510. Therefore, it was concluded that selection of brood fish using both the PCR test and ELISA antibody titers could help prevent vertical transmission of BFNNV in larval production of barfin flounder.

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

“…In addition, the fish rearing temperature may also be an important factor influencing fish response to Poly(I:C), and should be addressed in future experiments. Finally, difficulties were encountered during the grow-out and adult stages in sea cages of open aquaculture systems due to horizontal transmission of fish pathogenic viruses in Japan, although a stable seed production in separate facilities was accomplished by preventing viral transmission (Mushiake et al 1994, Watanabe et al 2000, Yoshimizu 2003, 2009, suggesting that the environment of the culture system was contaminated with fish pathogenic viruses. Moreover, a new problem of mixed infection with unknown pathogenic viruses was also revealed in VNN-affected fish in Japan (Kokawa et al 2008).…”

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

“…Betanodavirus infection can be influenced by host factors such as age [1,3], environmental factors such as water temperature [106,115,125] and other stress factors such as suboptimal feed, suboptimal water quality, crowding, transport and repeated spawning of broodstock [55,64,84,115]. The virus can be transmitted both horizontally [15,49,71,99] and vertically [2,7,14,49,83,84,92,102,119]. It can persist in the host for a long time sub-clinically and may cause severe mortality under extreme environmental conditions [105].…”

“…It can persist in the host for a long time sub-clinically and may cause severe mortality under extreme environmental conditions [105]. The horizontal transmission may occur from infected fish, feed, contaminated trash fish/carrier animals and contaminated water supply [18,44,47,69,87,119]. The cannibalistic nature of fish such as Asian seabass and brown-marbled grouper fingerlings may also enhance the horizontal transmission of the virus [78].…”

A novel quantitative immunomagnetic reduction assay for Nervous necrosis virus

“…5,15 Several diagnostic tests, such as fluorescent antibody test and enzymelinked immunosorbent assay (ELISA) can be used to differentiate NNV from other fish viruses. 7,25,29 Standard reverse transcription polymerase chain reaction (RT-PCR) methods have been applied for the detection of NNV, 17,21 including a NNV-specific primer pair recommended by the World Health Organization. 30 Real-time RT-PCR methods have also been developed for the detection and quantification of NNV.…”