Purification and Western-blot assay of the capsid protein of the red-spotted grouper nodavirus

Red-spotted grouper nodavirus Dayawan isolate（RG-CN）was purifed by differential centrifugation, sucrose density gradient centrifugation（10%～40%，W/V） and CsCl isopyknical density centrifugation（30%～40%，W/W）. The results showed that the viral particles exhibited a buoyant density of 1.3102～1.3243 gcm-3. By Western-blot assay, viral capsid protein showed two polypeptides with molecular weights of 37 and 31 kDa, mainly being 31 kDa.