Separation Of Shrimp White Spot Baculovirus Purification, Ultrastructure And Morphogenesis Of The Study

WSBV was purified from the heads of Penaeus monodon with white spot syndrome on the carapace. The baculovirus was also purified from the heads of Penaeus japonicus and larval Penaeus chinensis which were fed on the hepatopancreas of Penaeus monodon. The nucleic acid of WSBV is demonstrated as high MW DNA. The polypeptides with molecular weight of 49.8 KDa is the major polypeptides of capsids. The enveloped virion is 270-300 X 90-l2Onm, and has a tail, which is an envelope extension. The nucleocapsid is a helical cylinder and is formed of two cap structures at the both ends and 13 helical bands in the middle. One helical band is made up of 11 capsomeres that are formed by 3-row-parallel protein subunits. An ultrastructure model of nucleocapsid has been proposed. WSBV was observed in the tissues of larval Penaeus chinensis and Penaeus japonicus. The baculovirus is a rod-shaped, enveloped, non-occluded virus. Viral morphogenesis begins in the nuclei and its process is composed of four stages: the formation of viral stroma, the formation of membrane, the assembly of virus and the formation of complete virons. During the viral assembly, sometimes two or three nucleocapsids use one membrane to assemble. This causes two results. One is one membrane fragment envelops respectively each nucleocapsid so that two complete virions are formed each of which is one nucleocapsid in one envelope. The other is virions are formed which are two or three nucleocapsids in one envelope.