Pathogenicity of penaeid rod-shaped DNA virus (PRDV) to kuruma prawn in different developmental stages

Abstract

Penaeid acute viremia (PAV) caused by penaeid rod-shaped DNA virus (PRDV: one of white spot baculovirus complex) is the most serious disease affecting kuruma prawn (Penaeus japonicus) culture in Japan. In this study an experimental challenge was carried out in different larval (nauplius, zoea and mysis) and postlarval (PL 1, 6, 9 and 11-12) stages of kuruma prawn in order to elucidate the difference in susceptibility to PRDV among different developmental stages of the host. The PRDV challenge was done by immersion in all the tested groups. No infections were recorded in the larval stages and PL1. The PL6 first showed mortality due to PAV on 10th day post-inoculation. The PL9 exhibited the onset of PAV on 5th day post-inoculation. In PL11-12, experimental PAV was produced more rapidly and resulted in higher mortality (78.6%). These results demonstrate that the PRDV-susceptibility of P. japonicus increases with the progress in developmental stage until PL12 and that PRDV may not display its pathogenicity in the larval and early postlarval stages younger than PL6.