Browsing Sustainable Production Systems of Aquatic Animals in Brackish Mangrove Areas by Author "Maeno, Yukio"

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    • Series: JIRCAS Working Report;No. 35

      Development for control methods for factors suppressing sustainable production of aquaculture species: Experimental transmission of piscine nodavirus-induced viral nervous necrosis to the orange-spotted grouper Epinephelus coioides 

      Maeno, Yukio; de la Peña, Leobert D.; Cruz-Lacierda, Erlinda R. (Japan International Center for Agricultural Sciences, 2003)
      Viral nervous necrosis (VNN) of larval orange-spotted grouper Epinephelus coioides has been recorded recently in the Philippines. The present study describes the pathogenicity of a piscine nodavirus (betanodavirus), the causative agent of VNN. Healthy orange-spotted grouper were challenged by intraperitoneal injection of the filtered tissue homogenate of VNN-diseased grouper. Abnormal swimming behavior, mortality, and necrosis and vacuolation of the brain and retina which are characteristics of VNN were reproduced in experimentally infected fish. Electron microscopic observations revealed that virus particles were present in the cytoplasm of the brain and retina; they were round in shape, without an envelope, 20 to 25 nm in diameter. The virus was reisolated from SSN-1 cells inoculated with the filtered tissue homogenate of survivors of all experimental doses. These results indicate that a piscine nodavirus from the orange-spotted grouper is the causative agent of mass mortality of this species in the Philippines.
    • Series: JIRCAS Working Report;No. 35

      Development of control methods of factors suppressing sustainable production of aquaculture species: Isolation of a piscine nodavirus from hatchery-reared sea bass Lates calcarifer in the Philippines 

      Maeno, Yukio; de la Peña, Leobert D.; Cruz-Lacierda, Erlinda R. (Japan International Center for Agricultural Sciences, 2003)
      The etiological study on mass mortality of larval sea bass Lates calcarifer cultured in the Philippines, demonstrated that the mortality was caused by viral nervous necrosis (VNN). Affected sea bass exhibited abnormal swimming behaviors and pale-gray coloration of the body. Pathological changes of affected fish showed marked vacuolation and necrosis in the retina and brain. The SSN-1 cell line inoculated with the filtrate of tissue material from affected fish demonstrated extensive cytopathic effects. Piscine nodavirus (betanodavirus), the causative agent of VNN, was detected by reverse transcription-polymerase chain reaction. Electron microscopic examinations revealed that spherical and non-enveloped viral particle 22-28 nm in diameter were detected in the cytoplasm of brain and retina of affected fish and in the cytoplasm of degenerated SSN-1 cells after CPE appeared. These results indicate that mass mortality of sea bass larvae in the Philippines was caused by piscine nodavirus.