Penaeus monodon

Abstract: Whlte spot syndrome baculovirus (WSBV) has been found across ddferent shrimp species and in different Asian countries. The detection of WSBV in shrimp with white spot syndrome has already been achieved by means of l-step polymerase chain reaction (PCR). In an attempt to establish a more sensitive assay, we evaluated the effect of 2-step amplification with nested primers on the sensitivity of WSBV diagnostic PCR. The sensitivity of the 2-step amplification was 10" to 10"imes higher than that of l-step amplification. Using both techniques, we successfully detected WSBV DNA in cultured and captured shrimp, crabs and other arthropods. Cultured Penaeus monodon (black tiger shrimp), P. japonicus (kuruma shrimp), P penicjllatus (red tail shrimp), and Metapenaeus 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 l-step WSBV diagnostic PCR, while others were positive only in 2-step WSBV diagnostic PCR. Use of the 2-step amplification protocol also detected a WSBV-specific DNA fragment in Macrobrachium rosenbergii (the giant freshwater prawn) exhibiting white spot syndrome. We also confirmed that WSBV exists in wild-caught shrimp (P monodon, f! japonicus, P semisulcatus and P penicillatus) and crabs (Charybdisferiatus. Portunuspelagicus and P. sanguinolentus) collected from the natural environment in coastal waters around southern Taiwan. Detection of WSBV in non-cultured arthropods collected from WSBV-affected shrimp farms revealed that copepods, the pest crab Hehce tndens, small pest Palaemonidae prawn and the larvae of an Ephydridae insect were reservoir hosts of WSBV. The relatedness between WSBV and Thailand's systemc ectodermal and mesodermal baculovirus (SEMBV) is d~scussed in this paper.

Abstract: White spot syndrome associated baculovlrus (WSBV) is the causative agent of a dlsease which has recently caused high shrimp mortahties and severe damage to shrimp cultures. In thls study, a strain of WSBV from black tiger shrimp Penaeus monodon was used to develop a diagnostlc tool for the detection of WSBV and related agent lnfect~ons in shnmp The vlnons were punfied from P monodon Infected with LVSBV V~ral genomlc DNA was extracted from purlfled vinons by treatlng the vlnons th proteinase K dnd cetyltnmethylammonium bromlde (CTAB) followed by phenol-chloroform extraction and ethanol precipitation A qualitative assessment Ivas performed using polymerase chain reaction (PCR) analys~s on the viral DNA and primers specif~c to shrimp genomic DNA in order to mon~ t o r shrimp DNA contamination In the viral genomic DNA preparations A WSBV genomlc DNA llbrary was constructed and based upon the sequence of the cloned WSBV DNA fragment, we deslgned a LVSBV-specific prlmer set for PCR to detect WSBV Infection in penaeld shrimp Samples which contained WSBV DNA yielded an evident ampl~f~cat lon product showing the expected moblllty of a 1447-bp DNA fragment whereas nuc le~c aclds extracted from tissue samples of clln~cally healthy shnmp showed no such DNA fragment, thereby confirming the speclficity of our pnmers By PCR with thls prlmer set, ~t was demonstrated that the causative agents of white spot syndrome in different shnmp specles are closely related An effective diagnostlc tool is thus provided for screening shnmp for \.VSBV infections, and may be important In preventing the further spread of this d~sease