Detection of PRDV from wild adult kuruma prawn

The present study was attempted to investigate the prevalence of penaeid ro d-shaped DNA virus (PRDV) in wild-caught adult kuruma prawn Penaeus japonic us using a 2-step polymerase chain reaction (PCR) as a detection method. Th e prawns examined were captured in 5 different areas of coastal waters in J apan from July 1996 to April 1998. Individual samples of hemolymph, stomach and gonad of these wild female and male prawns were submitted to PCR test. As a result, PRDV was detected in female (10.1%, 96/955) and male (6.7%, 2 1/314) prawns captured in all coastal waters, although most prawns showed n o white spot in the carapace. Higher detection rates were obtained from sto mach, ovary and testis than from hemolymph in female and male prawns. The p revalence of PRDV in adult prawns showed a seasonal and sex variation, i.e. the prevalence in summer (July to August) was higher than in winter (Decem ber to January) in female, and the prevalence in female was higher than tha t in male prawns. These results suggest that wild-captured adult kuruma pra wns, especially those collected in summer, become an infection source for v ertical transmission of PRDV when they are used as spawners.