DAO 42:83-89 (2000)  -  doi:10.3354/dao042083

Quasi-immune response of Penaeus japonicus to penaeid rod-shaped DNA virus (PRDV)

C. A. Venegas1,*, L. Nonaka1, K. Mushiake2, T. Nishizawa1, K. Muroga1,**

1Laboratory of Fish Pathology, Faculty of Applied Biological Science, Hiroshima University, Higashihiroshima 739-8528, Japan
2Kamiura Station of Japan Sea-Farming Association, Kamiura, Oita 879-2602, Japan
*Present address: Unit of Aquatic Animal Pathology, Dept. of Animal Pathology, Faculty of Veterinary Sciences, University of Chile, Santiago de Chile, Chile **Corresponding author. E-mail:

ABSTRACT: A quasi-immune response was demonstrated in kuruma prawn Penaeus japonicus infected naturally or experimentally with PRDV (penaeid rod-shaped DNA virus, also called white spot syndrome virus or WSSV), the causative agent of PAV (penaeid acute viremia). In the first step of this study, natural survivors 4 mo after a PAV outbreak demonstrated 94% relative percent survival (RPS) upon experimental PRDV challenge. Mortalities after challenge were confirmed by PRDV detection to be due to PAV using a PCR method. In the second step, experimental PAV survivors were produced by intramuscular (IM) injection of PRDV into naive shrimp subsequently reared collectively in a tank (A group) or individually in chamber units (B group). Survival was 41 and 90% in the A and B groups, respectively. A subsequent IM re-challenge of these PRDV survivor groups with PRDV made 32 d after the first challenge revealed a protective response with high RPS of 77 and 64%, respectively. These high survival rates suggested that PAV survivors (natural or experimental) were able to resist PRDV infection and that the resistance was not due to selection of naturally resistant shrimp during a PAV outbreak, but due to enhancement of an immune-like system (quasi-immune response) after exposure to PRDV. No PRDV neutralizing activity was revealed in the serum of the 4 mo natural survivors of the PRDV outbreak. However, it was found in their serum 17 d after they had been experimentally challenged with PRDV.

KEY WORDS: Penaeid acute viremia (PAV) · Penaeid rod-shaped DNA virus (PRDV) · White spot syndrome virus (WSSV) · Immune response · Penaeus japonicus

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