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Compared to fathead minnow, walleye demonstrate low susceptibility to experimental infection with VHSV IVb, regardless of route of exposure or water temperature at time of infection. In triplicate and duplicate groups, walleye were intraperitoneally (i.p.) injected (102-108 pfu/fish) or waterborne-exposed (w; 1.4 × 107 pfu mL−1) with VHSV IVb. High cumulative mortality (64-100%) and severe gross lesions associated with VHSV IVb infection were evident only in fish i.p. injected with 108 pfu at 12 °C. These fish had multifocal necrosis of several tissues including the gill and heart. There was no difference in mortality between walleye infected (w or i.p.) at 12 °C (spring stocking) compared with a declining temperature profile from 18 to 12 °C (fall stocking). There were significant differences ( P < 0.05) in mortality between four extant walleye strains following i.p. infection, indicating that the choice of walleye strain for stocking might be an important consideration. Viral antigen was found in both i.p. and w-exposed walleye using immunohistochemistry, mostly within the gill and skin of w-exposed fish and most prominently in dermal fibrocytes. VHSV IVb was detected in multiple tissues from 6 to 21 days post-infection using reverse transcriptase quantitative polymerase chain reaction (RT- qPCR). [ABSTRACT FROM AUTHOR]

A cell line, WE-cfin11f, with a fibroblast-like morphology was developed from a walleye caudal fin and used to study the intersection of thermobiology of walleye, Sander vitreus ( Mitchill), with the thermal requirements for replication of viral haemorrhagic septicaemia virus ( VHSV) IVb. WE-cfin11f proliferated from 10 to 32 °C and endured as a monolayer for at least a week at 1-34 °C. WE-cfin11f adopted an epithelial shape and did not proliferate at 4 °C. Adding VHSV IVb to cultures at 4 and 14 °C but not 26 °C led to cytopathic effects ( CPE) and virus production. At 4 °C, virus production developed more slowly, but Western blotting showed more N protein accumulation. Infecting monolayer cultures at 4 °C for 7 days and then shifting them to 26 °C resulted in the monolayers being broken in small areas by CPE, but with time at 26 °C, the monolayers were restored. These results suggest that at 26 °C, the VHSV IVb life cycle stages responsible for CPE can be completed, but the production of virus and the initiation of infections cannot be accomplished. [ABSTRACT FROM AUTHOR]

A letter to the editor related to fomites for viral hemorrhagic septicemia virus, is presented.

Cortisol at 1000 and 100 ng/ml, and less consistently at 10 ng/ml, inhibited increases in cell number and 3H-thymidine incorporation by cultures of the rainbow trout (Oncorhynchus mykiss) monocyte/macrophage cell line, RTS11. Cell viability was not altered by cortisol, although a small decline in the capacity of cultures to reduce the redox dye, Alamar Blue was observed. In cortisol-treated cultures, more round and fewer spread cells were evident. Similar results were observed with dexamethasone but not cortisone. The glucocorticoid receptor antagonist, RU-486, prevented the effects of cortisol on RTS11 proliferation, and shape. In co-culture with the spleen stroma cell line (RTS34st) or in medium conditioned by RTS34st, the proliferation of RTS11 was enhanced. Treating RTS11/RTS34st co-cultures or RTS11 cultures in RTS34st conditioned medium with cortisol did not inhibit RTS11 proliferation. Overall these experiments suggest that proliferation of rainbow trout macrophages is regulated by cortisol, but the effect is modulated by the cellular micro-environment, possibly through the release of cytokines. [Copyright &y& Elsevier]

Screening for environmental contaminants in milk is generally conducted by chemical analysis, yet such an approach may be time-consuming and expensive, and is not indicative of the physiological consequences of such exposure. The focus of this review is to summarize those constituents of milk that may be altered by maternal exposure to one of the most biologically active environmental pollutants, 2,3,7,8-tetrachlorodibenzo-p-dioxin, and to develop the case for their use as biomarkers of response. Several chemical and/or cellular components of milk are potentially useful as biomarkers, and may be developed as convenient, biologically relevant indicators of maternal exposure to dioxinlike compounds. [ABSTRACT FROM AUTHOR]

Collagenase was used to prepare primary cell cultures from rainbow trout, Oncorhynchus mykiss (Walbaum), gills. Although difficult to subcultivate, one primary culture led to the development of a cell, RTgil1-W1. RTgiIl-W1 grew in the basal medium, L-15, supplemented with foetal bovine serum at between 5 and 10%, but not in L-15 alone. The cells have been passaged approximately 50 times over a 4-year period. At confluency, the cell shape was predominantly polygonal or epithelial-like. RTgill-W1 cultures were demonstrated by DNA staining with H33258 and by growth on agar to be contaminated with mycoplasma, but this contaminant was eradicated by treatment with mycoplasma removal agent (MRA) and BM cyclin. [ABSTRACT FROM AUTHOR]