Detection of a Marine Birnavirus in Wild Molluscan Shellfish Species from Japan (original) (raw)
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Diseases of Aquatic Organisms, 2002
This study examines the seasonal changes of marine birnavirus (MABV) in seawater and the Japanese pearl oyster Pinctada fucata reared at different depths (2 and 15 m). Oysters and seawater were collected in 1998, and a 2-step PCR was carried out to detect MABV. Virus isolation was performed on the PCR-positive samples in the oyster. The detection rate of the MABV genome in the oyster was low during June, but increased after July at both 2 and 15 m depths. MABV was not isolated until after September, when isolation rates of 10 to 28.6% were recorded. The results suggest that growth of MABV in the oyster is similar at 2 and 15 m depth. In contrast, the MABV genome in seawater was present through the year at 15 m depth, but was not detected in summer at 2 m. This suggests that the virus is destroyed by UV and/or other factors at 2 m in summer, but is stable in deeper waters.
Seasonal change of infective state of marine birnavirus in Japanese pearl oyster Pinctada fucata
Archives of Virology, 2000
This study examines the seasonal occurrence and infective state of marine birnavirus (MABV) in cultured Japanese pearl oyster (Pinctada fucata). Planted oysters were sampled monthly in 1997 and 1998. To detect MABV in the oysters, PCR and virus isolation were carried out. Also, the indirect fluorescent antibody technique (IFAT) was performed to know the organs expressing viral antigens. The detection rate of the MABV genome by PCR was low during July to October, but increased after November. This virus was isolated only after October, with a 10-40% isolation rate. Results of the IFAT showed that the specific fluorescence was observed in hemocytes in September. Fluorescence in hemocytes decreased in January, but increased in liver parenchymal cells. These results suggest that MABV persistently infected hemocytes in summer with a small amount of genome and protein, and then the virus spread in winter into the parenchymal cells.
First isolation of an aquatic birnavirus from farmed and wild fish species in Australia
Diseases of Aquatic Organisms, 2000
During routine sampling and testing, as part of a systematic surveillance program (the Tasmanian Salmonid Health Surveillance Program), an aquatic birnavirus was isolated from 'pinhead' (fish exhibiting deficient acclimatisation on transfer to saltwater) Atlantic salmon Salmo salar, approximately 18 mo old, farmed in net-pens located in Macquarie Harbour on the west coast of Tasmania, Australia. The isolate grows readily in a range of fish cell lines including CHSE-214, RTG-2 and BF-2 and is neutralised by a pan-specific rabbit antiserum raised against infectious pancreatic necrosis virus (IPNV) Ab strain and by a commercial pan-specific IPNV-neutralising monoclonal antibody. Presence of the virus was not associated with gross clinical signs. Histopathological examination revealed a range of lesions particularly in pancreatic tissue. The virus was localised in pancreas sections by immunoperoxidase staining using the polyclonal antiserum and by electron microscopy. Examination by electron microscopy demonstrated that the virus isolated in cell culture (1) belongs to the family Birnaviridae, genus Aquabirnaviridae; (2) was ultrastructurally and antigenically similar to virus identified in the index fish; (3) is related to IPNV. Western blot analysis using the polyclonal rabbit antiserum confirmed the cross-reactions between various aquatic birnavirus isolates. In addition, PCR analysis of isolated viral nucleic acid from the index case indicated that the virus is more closely related to IPNV fr21 and N1 isolates than to other birnavirus isolates available for comparison. Sampling of other fish species within Macquarie Harbour has demonstrated that the virus is present in several other species of fish including farmed rainbow trout Oncorhynchus mykiss, wild flounder Rhombosolea tapirina, cod Pseudophycis sp., spiked dogfish Squalus megalops and ling Genypterus blacodes.