Inter-laboratory comparison of cell lines for susceptibility to three viruses: VHSV, IHNV and IPNV.
(17/793)
Eleven European National Reference Laboratories participated in an inter-laboratory comparison of the susceptibility of 5 selected cell lines to 3 fish pathogenic viruses. The test included viral hemorrhagic septicaemia virus (VHSV); infectious hematopoietic necrosis virus (IHNV) and infectious pancreatic necrosis virus (IPNV), and the cell lines derived from bluegill fry (BF-2), chinook salmon embryo (CHSE-214), epithelioma papulosum cyprini (EPC), fathead minnow (FHM) and rainbow trout gonad (RTG-2). The results showed that for isolation of VHSV, BF-2 and RTG-2 cells performed equally well and had higher sensitivity compared to the other cell lines. For IHNV, EPC and FHM cells gave the best results, and for IPNV it was BF-2 and CHSE-214 cells. FHM cells showed the largest variability among laboratories, whereas EPC was the cell line showing the smallest variability. (+info)
A Monte Carlo simulation model for assessing the risk of introduction of Gyrodactylus salaris to the Tana river, Norway.
(18/793)
The Tana river in northern Norway, the most productive salmon river in Europe, is free of Gyrodactylus salaris. Currently there is one salmon farm in operation on the Tana fjord. Because of the strong association between stocking of rivers with salmon and infestations with G. salaris there is national and international concern that the existing farm might lead to the introduction of the parasite to the Tana river. In response to these concerns a quantitative analysis of the risk of introduction of G. salaris to the Tana river was undertaken. A scenario tree, the Monte Carlo simulation model and results of the simulations including sensitivity analyses are presented and discussed. Results show that the probability of introduction of G. salaris to the Tana river via transfer of smolt to the existing salmon farm is extremely low primarily due to the low probability that the transferred smolt become infested. The total risk was very sensitive to changes in the salinity of the water at the sea site. (+info)
Identification of grass carp haemorrhage virus as a new genogroup of aquareovirus.
(19/793)
Three aquareovirus strains isolated from grass carp (Ctenopharyngodon idellus), geoduck clams (Panope abrupta) and herring (Clupea harengus) in North America and Asia were examined by RNA-RNA blot hybridization to determine their genogroup. The isolates from clams and herring were identified as members of genogroup A, but the isolate from grass carp did not hybridize to any of the known genogroups, suggesting that this virus probably represents a new, seventh genogroup. (+info)
Rational design, conformational studies and bioactivity of highly potent conformationally constrained calcitonin analogues.
(20/793)
Calcitonin is known for its hypocalcaemic effect and the inhibition of bone resorption, and is used therapeutically for the treatment of osteoporosis and Paget's disease. Our studies on the conformational features of human calcitonin (hCt) bioactivity have led to the conformationally constrained hCt analogue cyclo17,21-[Asp17, Lys21]hCt (1), which had a 5-10 times higher in vivo hypocalcaemic potency than hCt [Kapurniotu, A. & Taylor, J.W. (1995) J. Med. Chem. 38, 836-847]. We hypothesized that a stabilized, possibly type I beta turn/beta sheet conformation between residues 17 and 21 could play a crucial role in hCt bioactivity. Here, we designed, synthesized and studied the conformation and bioactivity of 19-member to 17-member ring-size analogues of 1 with the structure cyclo17,21-[Asp17,XX21]hCt with XX = Orn (2), Dab (3) and Dap (4), of the control peptide [Asp17,Orn21]hCt (5), and of the 19-member cyclo17,21-[Glu17,Dab21]hCt (6). Analyses of the far-UV CD spectra indicated increased type I beta turn and antiparallel beta sheet content in the bicyclic analogues compared with hCt. In the in vivo hypocalcaemic assay, cyclo17,21-[Asp17,Orn21]hCt (2) was found to have a 400-fold higher potency than hCt and was fourfold more potent than salmon calcitonin (sCt), which has been the most potent known Ct. Analogue 3 had a 30-fold higher potency than hCt, whereas the highly constrained analogue 4 was as potent as hCt. Bioactivity was not enhanced for the nonbridged compound [Asp17, Orn21]hCt (5), whereas cyclo17,21-[Glu17,Dab21]hCt (6) showed the same bioactivity as 1. This study identifies 2 as exhibiting the highest in vivo potency among currently known Cts, while it differs in only one amino acid residue from hCt, strongly suggesting that the introduced constraint may have served in 'freezing' hCt in a bioactive conformation. Our findings provide evidence for the first time that a beta turn/beta sheet conformation in region 17-21 of hCt and the topological features of the side chain of Asn17 are strongly associated with in vivo bioactivity, and offer a novel lead structure for a hCt-based drug for the treatment of osteoporosis and other bone-disorder-related diseases. (+info)
Purification and characterization of thyroid-hormone-binding protein from masu salmon serum. A homolog of higher-vertebrate transthyretin.
(21/793)
We purified a thyroid-hormone-binding protein (THBP) from serum of masu salmon at the stage of smoltification when the concentrations of endogenous thyroid hormones in plasma reach the highest levels. All steps of sequential column chromatography suggest that this THBP is responsible for most L-3,5,3'-triiodothyronine-binding activity in serum at this stage. The molecular mass of this protein was estimated to be 60 kDa by gel filtration but only 15 kDa by SDS/PAGE, which suggests that it is comprised of four identical subunits. The amino acid sequence of its N-terminal portion was highly similar to those of vertebrate transthyretins. These molecular features indicate that masu salmon THBP is a homolog of transthyretins from tetrapods. However, in contrast with mammalian transthyretins, the affinity of masu salmon transthyretin for L-3,5,3'-triiodothyronine was three times greater than for L-thyroxine. This rank order affinity is similar to that of avian and frog transthyretins. Scatchard analysis revealed that masu salmon transthyretin possesses a single class of binding site for L-3,5,3'-triiodothyronine, with a Kd of 13.8 nM at 0 degrees C. Taken together with the data reported by Chang et al. [Eur. J. Biochem. (1999) 259, 534-542], these results suggest that transthyretin has changed from a L-3,5, 3'-triiodothyronine-carrier protein to a L-thyroxine-carrier protein during mammalian evolution. (+info)
Resistance to reinfection in chinook salmon Oncorhynchus tshawytscha to Loma salmonae (Microsporidia).
(22/793)
Chinook salmon Oncorhynchus tshawytscha were experimentally infected per os with Loma salmonae and held in flow-through seawater tanks at 12 to 14 degrees C. The fish exhibited 100% infection when first examined at 7 wk post initial exposure (p.e.), and by 20 wk p.e. they had completely recovered from gill infections. The recovered fish were then re-exposed the following week. All of these fish showed strong protection to new L. salmonae infections, while naive fish exposed to the same inoculum developed the infection. Most of the re-exposed fish exhibited a few free spores or spores within phagocytes in the kidney interstitium at 20 to 29 wk p.e., but xenomas were not detected in either the gills or visceral organs. The kidney is the primary site of reticulo-endothelial activity, and thus these spores were likely deposited in the kidney by entrapment by fixed macrophages. It is possible that these spores provide immunologic stimuli to reinforce the resistance to new L. salmonae infections. (+info)
Shedding of Renibacterium salmoninarum by infected chinook salmon Oncorhynchus tschawytscha.
(23/793)
Laboratory studies of the transmission and pathogenesis of Renibacterium salmoninarum may describe more accurately what is occurring in the natural environment if test fish are infected by waterborne R. salmoninarum shed from infected fish. To quantify bacterial shedding by chinook salmon Oncorhynchus tschawytscha at 13 degrees C in freshwater, groups of fish were injected intraperitoneally with R. salmoninarum at either 1.3 x 10(6) colony forming units (CFU) fish (-1) (high-dose injection group) or 1.5 x 10(3) CFU fish (-1) (low-dose injection group). R. salmoninarum infection levels were measured in the exposed fish by the enzyme-linked immunosorbent assay (BKD-ELISA). At regular intervals for 30 d, the numbers of R. salmoninarum shed by the injected fish were calculated on the basis of testing water samples by the membrane filtration-fluorescent antibody test (MF-FAT) and bacteriological culture. Mean BKD-ELISA optical densities (ODs) for fish in the low-dose injection group were not different from those control fish (p > 0.05), and no R. salmoninarum were detected in water samples taken up to 30 d after injection of fish in the low-dose group. By 12 d after injection a proportion of the fish from the high-dose infection group had high (BKD-ELISA OD > or = 1.000) to severe (BKD-ELISA OD > or = 2.000) R. salmoninarum infection levels, and bacteria were detected in the water by both tests. However, measurable levels of R. salmoninarum were not consistently detected in the water until a proportion of the fish maintained high to severe infection levels for an additional 8 d. The concentrations of R. salmoninarum in the water samples ranged from undetectable up to 994 cells ml(-1) on the basis of the MF-FAT, and up to 1850 CFU ml(-1) on the basis of bacteriological culture. The results suggest that chinook salmon infected with R. salmoninarum by injection of approximately 1 x 10(6) CFU fish (-1) can be used as the source of infection in cohabitation challenges beginning 20 d after injection. (+info)
Isolation of different types of birnavirus from ayu Plecoglossus altivelis and amago salmon Oncorhynchus rhodurus cultured in the same geographic area.
(24/793)
A birnavirus was recently isolated from cultured ayu Plecoglossus altivelis on Shikoku island, Japan. The diseased fish displayed vertebral or vertical curvature and mild haemorrhage around the brain. Cytopathic effects (CPE) of the virus, including cell roundness, filamentous change and cell lysis, were observed in CHSE-214, RTG-2 and RSBK-2 cells. The virus isolated from ayu, designated the AY-98 strain, was found to be antigenically related to the marine birnavirus (MABV) Y-6 strain that originated from yellowtail Seriola quinqueradiata. AY-98 had a bi-segmented RNA genome and the same nucleotide sequence in the 310 bp VP2/NS junction as MABV Y-6. At the same time that the ayu epizootics occurred, another birnavirus (AM-98) was isolated from amago salmon Oncorhynchus rhodurus which were cultured 66 km away from the ayu farm. AM-98 showed a similar CPE and had the same host cell ranges as AY-98. However, AM-98 was serologically similar to the VR-299 strain of infectious pancreatic necrosis virus (IPNV) and their nucleotide sequences in the VP2/NS junction region showed 98% homology without changes at the amino acid level. In this study, the ayu strain AY-98 was grouped into MABV, whereas the amago salmon strain AM-98 was grouped into IPNV. This indicates that the 2 birnaviruses originated from different sources in spite of the fact that the places where they were isolated are close to one another. The results in this paper show a new aspect of the traditional consensus that the same serogroup of birnavirus distribute in close geographic areas. (+info)