Cp SBV, a systemic virus of the edible crab, Cancer pagurus (L.)

Following the description of the first crustacean virus by Vago (1966), reports of crab viral diseases were numerous during the 1970s and early 1980s (Bonami 1980; Johnson 1984; Mari & Bonami 1986; Adams & Bonami 1991). During this period, when shrimp aquaculture was beginning, pathological problems were scarce and crabs were used as biological models for crustacean virus investigations. More recently, little information was reported on crab viruses, although several shrimp viral diseases have been described (Lightner 1996). To date more than 50 viruses closely related to the known viral families (van Regenmortel, Fauquet, Bishop, Cartens, Estes, Lemon, Maniloff, Mayo, McGeoch, Pringle & Wickner 2000) have been recognized in aquatic crustaceans, with more than half of those from crabs (Shi 2000). During experimental investigations (Corbel, Zuprizal, Shi, Huang, Sumartono, Arcier & Bonami 2001) on the possible hosts of white spot syndrome virus (WSSV) – a highly pathogenic shrimp virus (Takahashi, Itami, Kondo, Maeda, Fujii, Tomonaga, Supamattaya & Boonyaratpalin 1994; Huang, Cai, Song, Wang, Yu & Yang 1995; Wongteerasupaya, Vickers, Sriurairatana, Nash, Akarajamorn, Boonsaeng, Panyim, Tassanakajon, Withyachumnarnkul & Flegel 1995) – a new viral disease was seen in the crab, Cancer pagurus (L.). Initially abnormal mortalities were recorded in a batch of negative control animals during WSSV transmission experiments and unknown virus-like particles were seen in the haemolymph of both WSSV-infected and negative control crabs. Because this agent was found free in large amounts in the haemolymph, and its characteristics were quickly recognized as close to those of the Bunyaviridae family (Bouloy 1991; van Regenmortel et al. 2000), it was designated Cancer pagurus systemic bunyalike virus (CpSBV). We report here, our investigations on this new virus, its isolation and purification, its structure and size, its development in infected cells and the nature, size and structure of its genome. Cancer pagurus, locally called tourteau or dormeur (sleeper), were caught in Brittany (France) and send alive to Montpellier. They were maintained in aerated sea water between 11 and 15 C, which was renewed every 3 days and they were fed three times a week with fresh mussels. After transportation, they were left to recover for 3 days before use in experimentation. After showing signs of disease, animals for further investigations were quarantined for 2 weeks, mortalities recorded, and the presence of virus particles in the blood checked by direct observation in transmission electron microscopy (TEM) ( Jeol Europe, Croissy, France) of a drop of haemolymph. For virus purification Tris-sodium (TN) buffer was used (0.02 m Tris–HCl, 0.4 m NaCl, pH 7.4). Low-speed centrifugations were performed in a JS13.1 rotor using a Beckman J2.21 preparativecentrifuge (Beckman Coulter, Roissy, France). For Journal of Fish Diseases 2003, 26, 121–126