Tissue distribution of striped jack nervous necrosis virus (SJNNV) in adult striped jack

Fluorescent antibody technique (FAT) and polymerase chain reaction (PCR) method were used to localize striped jack nervous necrosis virus (SJNNV, a nodavirus) in adult striped jack Pseudocaranx denier. One group of brood stocks (N = 4) consisted of 13-yr-old spawners whose reproductive fluids were SJNNV-positive by the PCR test. The other group (N = 4) consisted of 4-yr-old fish which had not previously spawned whose reproductive fluids were negative by the PCR test. Positive FAT reactions using an anti-SJNNV rabbit serum were observed in the gonad, intestine, stomach, kidney, and liver of the 13-yr-old fish but not in the corresponding organs of the 4-yr-old fish. In neither group were the viral antigens detected in the spinal cord, brain, or retina tissues, the target organs of the virus in striped jack larvae. The FAT results were consistent with PCR results for the detection of the SJNNV coat protein gene. The present results suggest that SJNNV originates in various organs of striped jack spawners and is shed from the intestine and gonad, which results in contamination of eggs.