WHITE SPOT SYNDROME BACULOVIRUS (WSBV) DETECTED IN CULTURED AND CAPTURED SHRIMP, CRABS AND OTHER ARTHROPODS

White spot syndrome baculovirus (WSBV) has been found across different shrimp species and in different Asian countries. The detection of WSB V in shrimp with white spot syndrome has already been achieved by mean s of 1-step polymerase chain reaction (PCR). In an attempt to establis h a more sensitive assay, we evaluated the effect of 2-step amplificat ion with nested primers on the sensitivity of WSBV diagnostic PCR. The sensitivity of the 2-step amplification was 10(3) to 10(4) times high er than that of 1-step amplification. Using both techniques, we succes sfully detected WSBV DNA in cultured and captured shrimp, crabs and ot her arthropods. Cultured Penaeus monodon (black tiger shrimp), P. japo nicus (kuruma shrimp), P. penicillatus (red tail shrimp), and Metapena eus ensis (sand shrimp) displaying white spot syndrome were collected from farms at different localities. One-step amplification of the DNA extracted from these shrimps consistently yielded an expected 1447 bp PCR product. Some of the tested specimens of cultured Scylla serrata ( mud crab) that exhibited white spot syndrome were positive in 1-step W SBV diagnostic PCR, while others were positive only in 2-step WSBV dia gnostic PCR. Use of the 2-step amplification protocol also detected a WSBV-specific DNA fragment in Macrobrachium rosenbergii (the giant fre shwater prawn) exhibiting white spot syndrome. We also confirmed that WSBV exists in wild-caught shrimp (P. monodon, P. japonicus, P. semisu lcatus and P. penicillatus) and crabs (Charybdis feriatus, Portunus pe lagicus and P. sanguinolentus) collected from the natural environment in coastal waters around southern Taiwan. Detection of WSBV in non-cul tured arthropods collected from WSBV-affected shrimp farms revealed th at copepods, the pest crab Helice tridens, small pest Palaemonidae pra wn and the larvae of an Ephydridae insect were reservoir hosts of WSBV . The relatedness between WSBV and Thailand's systemic ectodermal and mesodermal baculovirus (SEMBV) is discussed in this paper.