Virus taxonomy: classification and nomenclature of viruses

Toxic effects of the non-steroidal anti-inflammatory drug diclofenac: Part I: histopathological alterations and bioaccumulation in rainbow trout☆

Lactic acid bacteria in fish: a review.

Disease and health management in Asian aquaculture.

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Fish viruses and fish viral diseases.

Vibrio harveyi infection was found to occur in pond-reared black tiger prawn in Thailand. The diseased prawns with a hepatopancreatic infection of V. harveyi showed bacterial invasions and multiplication in the tubular lumens. This condition was followed by necrosis of hepatopancreatic cells and the thickened basal lamina, subsequent granulomatous encapsulation of the invaded tubules, and production of granulation tissue around granulomatous lesions. Heavy bacterial multiplication in the hepatopancreatic tubules caused systemic bacterial dissemination, which resulted in marked necrosis in the heart and lymphoid organ. On the other hand, two prawns with percuticular infection by V. harveyi had bacterial invasions in the subcuticular, spongy connective tissue in the telson, and systemic dissemination was followed by the occurrence of bacteriaphagocytizing hemocytes in the various tissues. Both types of isolates (chitinase positive and negative) were moderately pathogenic to prawn; intramuscular inj...

Histopathology, Biochemistry, and Pathogenicity of Vibrio harveyi Infecting Black Tiger Prawn Penaeus monodon

A rhabdoviral disease occurred in farmed populations of market sized Japanese floun- der (hirame) Paralichthys olivaceus in the Seto Inland Sea of Japan in 1996. The causative agent was identified as viral hemorrhagic septicemia virus (VHSV) based on morphological, immunological, and genetic analyses. Diseased fish that were artificially injected with a representative virus isolate showed the same pathological signs and high mortality as observed in the natural outbreak. This is the first report of an outbreak of VHSV infection in cultured fish in Japan. Clinical signs of diseased fish included dark body coloration, an expanded abdomen due to ascites, congested liver, spleno- megaly, and a swollen kidney. Myocardial necrosis was most prominent and accompanied by inflam- matory reactions. Necrotic lesions also occurred in the liver, spleen and hematopoietic tissue, and were accompanied by circulatory disturbances due to cardiac failure. Hemorrhagic lesions did not always appear in the lateral musculature. Transmission electron microscopy revealed many rhab- dovirus particles and associated inclusion bodies containing nucleocapsids in the necrotized myocardium. The histopathological findings indicated that the necrotizing myocarditis could be con- sidered a pathognomonic sign of VHSV infection in Japanese flounder.

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An outbreak of VHSV (viral hemorrhagic septicemia virus) infection in farmed Japanese flounder Paralichthys olivaceus in Japan.

Many species of ornamental freshwater fishes are imported into Japan from all over the world. We found African lampeye Aplocheilichthys normani and dwarf gourami Colisa lalia suffering from an iridovirus infection just after being imported by tropical fish wholesalers from Singapore. African lampeye were cultured on the Indonesian Island of Sumatra and dwarf gourami were cultured in Malaysia before export. Diseased fishes displayed distinct histopathological signs of iridovirus infection: systemic appearance of inclusion body-bearing cells, and necrosis of splenocytes and hematopoietic cells. Electron microscopy revealed viral particles (African lampeye:180 to 200 nm in edge to edge diameter; dwarf gourami: 140 to 150 nm in diameter) in an inclusion body within the cytoplasm of inclusion body-bearing cells as well as in the cytoplasm of necrotized cells. Experimental infection with an iridovirus isolate from African lampeye (ALIV) revealed pathogenicity of ALIV to African lampeye and pearl gourami Trichogaster leeri. Polymerase chain reaction (PCR) products from ALIV and an iridovirus isolate from dwarf gourami (DGIV) using iridovirus-specific primers were indistinguishable. The nucleotide sequence of PCR products derived from ALIV (696 base pairs) and DGIV (701 base pairs) had 95.3% identity. These results indicate that ALIV and DGIV have a single origin.

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Iridovirus disease in two ornamental tropical freshwater fishes: African lampeye and dwarf gourami.

Tropical iridovirus infection causes severe epizootic resulting in mass mortalities and large economic losses in freshwater ornamental fishes cultured in Southeast Asian countries, in wild fish seedlings captured in South China Sea, and in marine fishes farmed in Japan, Singapore, and Thailand. All of tropical iridovirus-infected fishes histopathologically showed the systemic formation of inclusion body-bearing cells and necrosis of virus-infected splenocytes and hematopoietic cells. We designed primer sets for the ATPase gene and the major capsid protein (MCP) gene and sequenced the PCR products derived from 5 iridovirus isolates from sea bass in South China Sea, red sea bream in Japan, brown-spotted grouper with a grouper sleepy disease in Thailand, dwarf gourami from Malaysia and African lampeye from Sumatra Island, Indonesia. The ATPase gene and the MCP gene of these 5 viral isolates were highly homologous (> 95.8%, > 94.9% identity, respectively) and the deduced amino acid sequences of the ATPase and the MCP were also highly identical (> 98.1%, > 97.2% identity, respectively). Based on the high homology, these 5 isolates of tropical iridovirus from various fishes in geographically different regions were determined to have a single origin and to be native to Southeast Asian regions. However, these sequences were far different from those of members of the genera Ranavirus, Lymphocystivirus and Iridovirus in the Family Iridoviridae. We propose a new genus "Tropivirus" for tropical iridovirus in the Family Iridoviridae.

Viral DNA sequences of genes encoding the ATPase and the major capsid protein of tropical iridovirus isolates which are pathogenic to fishes in Japan, South China Sea and Southeast Asian countries.

A comparative histopathological study was made on natural infections of Edwardsiella tarda in Japanese flounder; Paralichthys olivaceus, red sea bream; Pagrus major, tilapia; Tilapia nilotica and Japanese eel; Anguilla japonica, and of Edwardsiella ictaluri in channel catfish; Ictalurus punctatus. Histopathological aspects of E. tarda infection of Japanese flounder and Japanese eel, and E. ictaluri infection of channel catfish were commonly characterized by suppurative inflammation in the infected lesions. Histopathological aspects of E. tarda infection of tilapia and red sea bream were commonly characterized by granulomatous inflammation preceded by macrophage infiltration in the infected lesions. As to inflammatory cells, causative bacteria overcame phagocytotic activities of neutraphils and macrophages resulting in intracellular multiplication. However, the number of bacteria was obviously decreased in the granulomas.

Teruo Miyazaki

Papers

Histopathology, Biochemistry, and Pathogenicity of Vibrio harveyi Infecting Black Tiger Prawn Penaeus monodon

An outbreak of VHSV (viral hemorrhagic septicemia virus) infection in farmed Japanese flounder Paralichthys olivaceus in Japan.

Iridovirus disease in two ornamental tropical freshwater fishes: African lampeye and dwarf gourami.

Viral DNA sequences of genes encoding the ATPase and the major capsid protein of tropical iridovirus isolates which are pathogenic to fishes in Japan, South China Sea and Southeast Asian countries.

Comparative Histopathology of Edwardsiellosis in Fishes