Persistent infections in salmonid fish cells with infectious pancreatic necrosis virus (IPNV)*

Abstract. Two cell lines that are persistently infected with IPN virus have been established. Viral persistence in the cultures was demonstrated by the detection of infectious virus (10²-10^5,5 TCID/ml₅₀) in the culture fluids, by specific immunofluorescence, and by their resistance to superinfection by homologous virus. The growth, rate of these cells was indistinguishable from normal, uninfected cells. Virus stocks harvested from persistently infected cultures contained a greater proportion of defective, interfering particles than those from lytically infected cells which suggests that these particles may be responsible for the maintenance of these carrier cultures.     

Comparative sensitivity of five fish cell lines to wild type infectious haematopoietic necrosis virus from two Oregon sources

Abstract. Five fish cell lines (CHSE-214, STE-137, RTG-2, EPC and FHM) were compared for sensitivity to infectious haematopoietic necrosis virus (IHNV) from samples obtained from naturally-infected fish. Infectious ovarian fluids were obtained from steelhead trout, Salmo gairdneri Richardson, at the Round Butte Hatchery in central Oregon and tissue homogenates were prepared from chinook salmon, Oncorhynchus tshawytscha (Walbaum), alevins during an IHN virus epizootic at the Elk River Hatchery in coastal Oregon. The only lines to show characteristic viral cytopathology by plaque or end-point dilution assay for the steelhead trout virus isolate were the EPC and FHM cell lines. The chinook salmon isolates produced CPE in CHSE-214, STE-137, FHM and EPC cells. The titre of the salmon virus isolate was 10-50-fold higher on FHM and EPC cells by both assay methods. Neither by end-point nor plaque assay did the Round Butte or Elk River isolates produce CPE on RTG-2 cells. With both virus isolants both cell lines showed that greater sensitivity was obtained with plaque assay than with end-point titration. Pre-treatment of the cells with the polycation, polybrene, did not increase the virus titre in either assay. However, a transient enhancement in virus titre was observed in polybrene-treated STE-137 and CHSE-214 cells.     

Effect of polybrene on the infectivity of infectious haemopoietic necrosis virus in tissue culture

Abstract. enhancement of plaque formation by IHN virus on CHSE-214 cells was obtained with 2–5 /(μ/ml polybrene. The enhancement is due to increased infectivity of small plaque variants in the IHN virus stock.     

High glucose up-regulates TRAIL-R4 expression in THP-1 cells and smooth muscle cells

AIM: To evaluate the expression of TNF-related apoptosis inducing ligand receptor 4 (TRAIL-R4) of THP-1 cells and human aorta smooth muscle cells under high glucose intervention. METHODS: Monocytic cell line THP-1 was incubated with PMA to induce to mature macrophage, Adhesion molecules CD11b and CD11c were assessed by FACS. TRAIL-R4 levels in THP-1 cells treated with different glucose concentrations were determined by Western blotting. The changes of TRAIL-R4 protein expressions were observed at different time points in human aorta smooth muscle cells. Western blotting was employed to evaluate TRAIL-R4 levels after the intervention of PKC activator. RESULTS: Incubation with 160 nmol/L PMA induced mature macrophages. TRAIL-R4 expression was up-regulated after incubation with 20 mmol/L glucose in macrophages. TRAIL-R4 was elevated in a time course manner under high glucose level in human aorta smooth muscle cells. Moreover, activation of PKC induced TRAIL-R4 expressions. CONCLUSION: Up-regulated TRAIL-R4 protein levels induced by high glucose levels might inhibit apoptosis of monocytes and smooth muscle cells and contribute to the progression of atherosclerosis.     

A comparison of detection methods for infectious haematopoietic necrosis virus

Abstract. A comparative study of immunological methods for detecting infectious haematopoietic necrosis virus (IHNV) was made. The anti–IHNV antibody titre was measured by solid phase direct binding assays with'¹²⁵iodinated Protein A from Staphylococcus aureus and with immunoperoxidase staining. The binding antibody titre was much higher than that obtained in the virus neutralization assay. The high binding antibody titre of rabbit anti–IHNV sera made the development of two immunological tests for IHNV possible. Virus–specific proteins were detected on nitrocellulose membranes after transfer from denaturing polyacrylamide gels. The immunological methods were highly specific, sensitive lo less than 10 ng of virus protein, and were useful in characterizing the different strains of IHNV.     

The route of entry and progression of infectious haematopoietic necrosis virus in Oncorhynchus mykiss (Walbaum): a sequential immunohistochemical study

Abstract. Steelhead trout, Oncorhynchus mykiss (Walbaum), fry were experimentally infected with infectious haematopoietic necrosis virus (IHNV) Round Butte 1983 (Type 1). Fry were sampled daily, before and during the epizootic. Fish tissues were tested for infectious virus by tissue culture assay and for IHNV nucleocapsid protein by alkaline phosphatase immunohistochemistry (APIH). The progression of virus through the tissues was followed by APIH until the fourteenth day. Viral infection progressed from two major sites: from the gills into the circulatory system; and from the oral region into the gastrointestinal tract and then into the circulatory system. Once in the blood, virus was disseminated to virtually every organ. Progression of IHNV within and between organs is discussed.