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

Barfin flounder nervous necrosis virus (BFNNV), the causative agent of vira l nervous necrosis (VNN) of barfin flounder, is vertically transmitted from spawners to larvae. In the present study, an ELISA with a recombinant prot ein of BFNNV was performed for the detection of antibodies against BFNNV an d applied for the selection of brood fish in order to prevent viral vertica l transmissions. Brood stocks were divided into 4 groups based on ELISA ant ibody titers (less than or equal to 10, 20, 40 and >40), and the BFNNV stat us of the brood stocks was determined by PCR. BFNNV was detected from the b rood fish in the group with an antibody titer of >40 but not from those wit h titers less than or equal to 10, 20 and 40. The offspring obtained from P CR-negative brood fish pairs in each group of ELISA antibody titers were su bsequently reared for observation of VNN occurrence. VNN occurred in juveni les from 2 of 9 pairs of spawners with an antibody titer greater than or eq ual to 40, but did not occur in spawners with an antibody titer of less tha n or equal to 10. Therefore, it was concluded that selection of brood fish using both the PCR test and ELISA antibody titers could help prevent vertic al transmission of BFNNV in larval production of barfin flounder.