Early detection of SARS-CoV in throat wash and saliva suggests that these specimens are ideal for SARS diagnosis.

A large icosahedral virus was isolated from diseased grouper Epinephelus tauvina. The virus grew well in several cultured fish cell lines, with stable and high infectivity after serial passages in grouper cell line (GP). The virus was sensitive to both acid and heat treatments. Virus replication was inhibited by 5-iodo-2-deoxyuridine (IUDR), indicative of a DNA-containing genome. The virus infectivity was reduced with ether treatment, suggesting that the virus was lipid-enveloped. Electron micrographs showed abundant cytoplasmic icosahedral virons in the virus-infected GP cells. The size of the intracellular nucleocapsid was 154 nm between the opposite sides, or 176 nm between the opposite vertices with an inner electron-dense core of 93 nm. Virus particles were released through budding from plasma membranes with a size of 200 nm in diameter. SDS-PAGE of purified virus revealed 20 structural protein bands and a major capsid protein (MCP) of 49 kDa. A DNA fragment of ~500 nucleotides was successfully amplified by polymerase chain reaction (PCR) using the primers from conserved regions of the MCP gene of frog virus 3 (FV3), the type species of Ranavirus. Subsequent multiple alignment and phylogenetic analysis showed that the newly isolated grouper virus was closely related to largemouth bass virus (LMBV), FV3 and Regina ranavirus (RRV). Our data suggests that the virus isolate is a novel member of genus Ranavirus, family Iridoviridae. We tentatively name the virus as Singapore grouper iridovirus (SGIV). SGIV was able to cause serious systemic disease capable of killing 96% of grouper fry. KEY WORDS: Fish virus · Iridovirus · Ranavirus · Iridoviridae · Grouper · Epinephelus tauvina Resale or republication not permitted without written consent of the publisherDis Aquat Org 53: [1][2][3][4][5][6][7][8][9] 2003 significant economic losses in some Singapore marine net-cage farms. The pathogen was suggested as an iridovirus based on histopathological and morphological evidence. However, the virus was not isolated by cell culture, and no biochemical data are available to confirm the virus as a member of the family Iridoviridae (Chua et al. 1994). In 1998, an outbreak of the same disease occurred in fry and adult brown-spotted groupers. The grouper fry were imported from other SE Asian countries and cultured in fish farms in Singapore. The outbreak lasted several weeks and resulted in more than 90% mortality. The present work describes isolation of the viral pathogen in cell culture, investigation of virus infectivity and pathogenicity, and characterization of the virus based on biochemical, structural and molecular properties. MATERIALS AND METHODSCell lines and maintenance. Three local tropical marine-fish cell lines and 3 commercial fish cell lines were used. Grouper (GP) embryo cells from brownspotted grouper Epinephelus tauvina (Chew-Lim et al. 1994), Asian seabass fry (SF) cells from Lates calcarifer (Chang et al. 2001), and Asian seabass (SB) embryo cells (Chong et al. 1987) were cultured in Eagles' mi...

Thirty-one cases of severe acute respiratory syndrome (SARS) occurred after exposure in the emergency room at the National Taiwan University Hospital. The index patient was linked to an outbreak at a nearby municipal hospital. Three clusters were identified over a 3-week period. The first cluster (5 patients) and the second cluster (14 patients) occurred among patients, family members, and nursing aids. The third cluster (12 patients) occurred exclusively among healthcare workers. Six healthcare workers had close contact with SARS patients. Six others, with different working patterns, indicated that they did not have contact with a SARS patient. Environmental surveys found 9 of 119 samples of inanimate objects to be positive for SARS coronavirus RNA. These observations indicate that although transmission by direct contact with known SARS patients was responsible for most cases, environmental contamination with the SARS coronavirus may have lead to infection among healthcare workers without documented contact with known hospitalized SARS patients.

From 1992 onwards, outbreaks of a previously unknown illness have been reported in Asian seabass (Lates calcarifer) kept in maricultures in Southeast Asia. The most striking symptom of this emerging disease is the loss of scales. It was referred to as scale drop syndrome, but the etiology remained enigmatic. By using a next-generation virus discovery technique, VIDISCA-454, sequences of an unknown virus were detected in serum of diseased fish. The near complete genome sequence of the virus was determined, which shows a unique genome organization, and low levels of identity to known members of the Iridoviridae. Based on homology of a series of putatively encoded proteins, the virus is a novel member of the Megalocytivirus genus of the Iridoviridae family. The virus was isolated and propagated in cell culture, where it caused a cytopathogenic effect in infected Asian seabass kidney and brain cells. Electron microscopy revealed icosahedral virions of about 140 nm, characteristic for the Iridoviridae. In vitro cultured virus induced scale drop syndrome in Asian seabass in vivo and the virus could be reisolated from these infected fish. These findings show that the virus is the causative agent for the scale drop syndrome, as each of Koch’s postulates is fulfilled. We have named the virus Scale Drop Disease Virus. Vaccines prepared from BEI- and formalin inactivated virus, as well as from E. coli produced major capsid protein provide efficacious protection against scale drop disease.

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