Chemiluminescence of phagocytic cells isolated from the pronephros of striped bass.

Phagocytosis of bacterial fish pathogens by cells isolated from the pronephros of striped bass (Morone saxatilis) was measured using an assay of chemiluminescence. Results of the assay, which proved to be quite reproducible, indicated that the degree of phagocytosis was related to the number of bacteria employed and to the species of bacteria eliciting the response. Cells from individual fish gave similar phagocytic responses but of different magnitudes.

Effects of metals on the chemiluminescent response of rainbow trout (Salmo gairdneri) phagocytes.

Quantification of an induced chemiluminescent (CL) response in phagocytes is currently being evaluated as an indicator system for determining those environmental pollutants that may predispose fish to disease. A CL assay was developed using phagocytes from the pronephros of rainbow trout (Salmo gairdneri). The CL response of phagocytes to phorbol myristate acetate, a chemical inducer of CL, was shown to be dose-dependent. The response to five species of bacteria was also evaluated. Staphylococcus aureus and Aeromonas hydrophila produced the most intense CL responses and the longest duration of response (100 min.) Yersinia ruckeri induced an immediate strong CL response of short duration (20 min.) whereas Vibrio anguillarum and Aerococcus viridans failed to stimulate CL under the test conditions employed. The effect of sub-toxic levels of Cu, Al, and Cd on the CL response of phagocytes to S. aureus was examined using phagocytes exposed to the metals immediately before assay or after 1 hr or 24 hr exposure times. Copper caused a significant decrease in CL to the baseline level under all treatment conditions upon stimulation with S. aureus. Similar results were obtained with Al except that the decrease in CL, although significant, was not to the baseline level. In contrast, Cd caused a significant increase in CL when added 1 hr prior to or immediately before the assay; but, following a 24 hr exposure, the results were variable, in that either no change or a decrease was observed. The addition of Cu to phagocytes already exhibiting a strong CL response to S. aureus caused an immediate decrease in CL to that seen with the negative controls.

Monoclonal antibodies to the Sp strain of infectious pancreatic necrosis virus.

Twelve hybrids secreting antibody to the Sp serotype of infectious pancreatic necrosis virus (IPNV) were isolated from the fusion of murine myeloma cells and spleen cells from mice immunized with pelleted virus. All of the monoclonal antibodies possessed the kappa (K) light chain isotype. Nine contained the mu (M), two had the gamma 2a (G2a), and one had the gamma 1 (G1) heavy chain isotype. Using an enzyme-linked immunosorbent assay (ELISA), 10 antibodies were found to be broadly reactive against partially purified representatives of the three serotypes of IPNV, the Sp, Ab, and VR-299 strains. The other two antibodies reacted with the Sp serotype alone. Characterization by immunostaining of viral polypeptides electrophoretically transferred to nitrocellulose sheets was possible only with IgG type antibodies. One of the specific monoclonal antibodies was shown to be directed against the major capsid protein while the other specific monoclonal antibody and the broadly reacting one reacted with the low molecular weight viral polypeptides.

Effect of exogenous corticosteroids on circulating virus and neutralizing antibodies in striped bass (Morone saxatilis) infected with infectious pancreatic necrosis virus.

Corticosteroids have been reported to induce immunosuppression in fish exposed to many types of bacterial antigens. We document a similar phenomenon in fish exposed to infectious pancreatic necrosis virus (IPNV). Fingerling striped bass that were injected with the steroid triamcinolone acetonide (100 mg/kg body weight) 24 hours before receiving intraperitoneal inoculation with IPNV became viremic 3 days post inoculation (dpi) and virus was still detected in the buffy coat cells 14 dpi. In contrast, viremia could not be detected after 7 dpi in fish that received virus but not steroids. Circulating virus neutralizing antibodies were first detected in steroid treated fish at 10 dpi compared to 7 dpi for the virus injected fish and titers were consistently lower in the steroid group. Steroid treatment of chronic IPNV-carriers did not induce detectable viremia nor alter circulating antibody levels in chronic IPNV-carriers. None of the striped bass demonstrated clinical signs of viral disease.

Transmission studies of sarcoma in the soft-shell clam, Mya arenaria.

Transmission experiments with adult soft-shell clams (Mya arenaria) demonstrated that clam sarcomas are transmissible with hemolymph from neoplastic animals but not with cell-free ultrafiltrates. Non-neoplastic clams were injected with either hemolymph from neoplastic clams or a cell-free ultrafiltrate prepared from a subsample of the same hemolymph. Injected clams were held in separate flow-through aquaria and examined for sarcomas by histocytology and histology. Data at 17 weeks showed a 44% prevalence of sarcomas in clams injected with neoplastic inoculum. No sarcomas were observed either in clams injected with a cell-free ultrafiltrate or in the control animals. The lack of sarcomas in clams injected with the ultrafiltrate argues against a viral etiology for the disease.

Isolation and characterization of adeno-associated viruses from bovine adenovirus types 1 and 2.

Hemagglutinating DNA viruses of 20 nm diameter were isolated from bovine adenovirus types 1 and 2. The isolates were heat stable, chloroform resistant, and defective. Their densities were 1.38 to 1.39 g/cm3, and they were found to be serologically identical to the bovine adeno-associated virus strain X7. A partial antigenic relationship was found between these and the canine adeno-associated virus.

Transformation of cell cultures as a parameter for detecting the potential carcinogenicity of antischistosomal drugs.

Several antischistosomal drugs and their metabolites were found to transform rat embryo cell cultures persistently infected with the Rauscher leukemia virus. The transformed cells produced fibrosarcomas when implanted into newborn rats. Cell cultures treated with either virus or chemical alone were not transformed nor were they invasive in rats. The advantages of early screening of developmental drugs in cell culture systems are discussed.

Persistent infection of a human lymphocyte cell line (Molt-4) with the kilham rat virus.

Inoculation of a human thymus-derived lymphocyte cell line (Molt-4) with the Kilham rat virus resulted in persistently infected cultures, that released infectious virus for periods up to seven months. At any time following infection, a small percentage of the cells were positive for rat virus antigens as determined by immunofluorescene assay.

Human lymphoblastoid cells as hosts for parvoviruses H-1 and rat virus.

A human T-cell line (Molt-4) was shown by viral hemagglutination and infectivity assays to support the replication of rat virus (RV) and H-1 virus. In addition, H-1 virus, but not RV, multiplied in two human B-cell lines, AV-1 and NC-37. The ability to bind radioactively labeled RV was demonstrated for each of the cell lines, but viral adsorption occurred to a greater degree with Molt-4 cells than with either AV-1 or NC-37 cells. After challenge with RV, virus-specific antigens were detected in cells of the B-cell lines by the indirect immunofluorescence technique. Infection of AV-1 or NC-37 cells by RV apparently results in an abortive cycle of virus replication. Differences among the three cell lines that might influence with H-1 virus or RV are discussed.