Production of anti-infectious hematopoietic necrosis virus (IHNV) substances by intestinal bacteria

Third Asian Fisheries Forum. 26-30 October 1992. Singapore

Isolation of a New Rhabdovirus from Cultured Hirame (Japanese Flounder, Paralichthys olivaceus) in Japan

First Asian Fisheries Forum. 26-31 May 1986. Manila, Phillipines

In vitro comparative ultrastructural observations on fish rhabdoviruses (HRV, IHNV, PER, EVA and EVEX)

Ultrastructural observation on fish rhabdoviruses, hirame rhabdovirus (HRV): Rhabdovirus olivaceus, infectious haematopoietic necrosis virus (IHNV), pike fry rhabdovirus (PFR), eel virus of America (EVA) and eel virus of Europe (EVEX) on RTG-2 cells was studied at 12 hr post-infection. Virus particles were found budding on the cell surfaces and were never observed in the vacuoles. Club-like or cord-like structures were easily observed on the cell surface of HRV infected cells. Appearances of these structures sometimes varied from club-like to cord-like structures, but all of them showed high electron density and included microfilaments. Most of them contained many viral particles on the surface. However, it was difficult to find such club- or cord-like structures on other fish rhabdoviruses-infected cells. PFR and EVEX infected-cells showed other rod-like or bubble-like structures on the surface, composed of membrane only.First symposium on diseases in Asian aquaculture. 26-29 November 1990. Bali, Indonesia

A new rhabdovirus isolated in Japan from cultured hirame (Japanese flounder) Paralichthys olivaceus and ayu Plecoglossus altivelis

In March 1984, a new rhabdovirus was isolated from moribund cultured hirame (Japanese flounder) Paralichthys olivaceus and from ayu Plecoglossus altivelis fry In Hyogo Prefecture, Japan. From February through May 1985, the virus was again isolated from hirame in seawater tanks in Hyogo and Kagawa Prefecture, and in Hokkaido, Japan. At temperatures between 5 and 20℃ the virus replicated and induced cytopathic effects (CPE), which progressed to eventual cytolysis, in susceptible cell lines, including FHM, EPC, BF-2, RTG-2, STE-137, HF-1, BB, YNK, CCO, and EK-1. The CHSE-214, KO-6 and CHH-1 cell lines were refractory. Maximum virus titers of about 10^9.3 to 10^9.8 TCID50ml^[-1] were obtained in FHM or EPC cell lines, and virus replicated optimally at 15 to 20℃. Virus particles were bullet-shaped and measured 80 nm × 180 to 200 nm. The isolate was sensitive to pH 3, to diethyl ether, and to heat (50℃, 2 min). Virus did not hemagglutinate human O type erythrocytes. Viral replication was not inhibited by 10^[-4] M 5-iododeoxyuridine. Infectivity was not reduced by antisera aginst infectious hematopoietic necrosis virus (IHNV), viral hemorrhagic septicemia virus (VHSV), spring viremia of carp virus (SVCV), pike fry rhabdovirus (PFRV), eel virus-America (EVA), and eel virus-European (EVX). The viral isolate was pathogenic for rainbow trout Salmo gairdneri by injection but not for chum salmon Oncorhynchus keta, coho salmon O. kisutch, masu salmon O. masou, or ayu fry by water-borne exposure. The new virus has been named Rhabdovirus olivaceus (hirame rhabdovirus, HRV)

Incidence of Fish Pathogenic Viruses among Anadromous Salmonids in the Northern Part of Japan, 1976-1987

During the period from September 1976 to December 1987, various species of mature salmonid fish, including masu (Oncorhynchus masou), chum (O. keta), pink (O. gorbuscha), kokanee salmon (O. nerka), charr (Salvelinus leucomaenis), and rainbow trout (O. mykiss), were examined to provide information on the distribution of pathogenic viruses in northern Japan. Virus inspections were conducted on ovarian fluids, mixed kidney and spleen specimens, epithelial tumor tissues, and blood samples. Four viruses were isolated during the course of this investigation. Infectious hematopoietic necrosis virus (IHNV) was found in the ovarian fluid of chum and masu salmon. Oncorhynchus masou virus (OMV), discovered in 1978 and specific to masu salmon, has been isolated from ovarian fluids and epithelial tumor tissues at 13 sampling sites. Chum salmon virus (CSV) was isolated from mixed kidney and spleen specimens from healthy chum salmon in 1978 and again in the ovarian fluids of masu salmon in 1987 at two localities on the coast of the Sea of Japan. Infectious pancreatic necrosis virus (IPNV) was isolated from masu salmon at two locations: once from tumor tissue in 1981 and a second time from an ovarian fluid sample in 1987. Viral erythrocytic necrosis (VEN) was found at four locations in the erythrocytes of chum and pink salmon in waters along the Okhotsk coast. Cytoplasmic particles with a hexagonal profile were found in the erythrocytes by electron microscopy.Seventeenth U.S.-Japan Meeting on Aquaculture. 16-18, 20 October 1988. Ise, Japan

Comparison of Structural Protein on Fish Rhabdoviruses

Oji International Symposium on Salmonid Diseases. 22-25 October 1991. Sapporo, Japan

Establishment and Characterization of Seven Continuous Cell Lines from Freshwater Fish

Seven continuous cell lines were established from salmonid and nonsalmonid fishes. Salmonid cell lines derived from rainbow trout Oncorhynchus mykiss and chum salmon O. keta were designated RTE and RTE-2 (rainbow trout embryo), RTT (rainbow trout tail), and SEH ("sake" or chum salmon embryo head). Nonsalmonid cell lines derived from pond smelt Hypomesus olidus, chevron snakehead Channa striata, and goldfish Carassius auratus were designated WF-1 ("wakasagi" fin), SHH (snakehead heart), and EPG (epithelioma papulosum of goldfish), respectively. Optimum growth for most of the cell lines was observed in Eagle's minimum essential medium buffered with sodium bicarbonate (26 mM) or a combination of sodium bicarbonate (8.9 mM) and tris (16 mM). Likewise, most of the cell lines showed optimum growth at the lowest NaCl concentration tested (0.116 M). Optimum growth temperatures ranged from 15 to 20℃ for the salmonid cell lines and from 15 to 30℃ for nonsalmonid cell lines. Except for RTT, the cell lines were heteroploid. Eleven fish viruses were used to test the susceptibility of these cell lines. Cell lines derived from salmonids developed cytopathic effects (CPE) when infected with 10 of the 11 fish viruses tested, except for RTT, which produced CPE with only 8 of the fish viruses. Six fish rhabdoviruses used in this study elicited a pronounced CPE when inoculated into nonsalmonid cell lines EPG, WF-1, and SHH. Among the new cell lines, RTE-2 showed the best potential for the isolation of fish viruses

Efficacy of Guava (Psidium Guajava) Extract Against Some Fish and Shrimp Pathogenic Agents

Guava (Psidium guajava) extract was tested for anti viral activity against the fish pathogenic viruses, infectious haematopoietic necrosis virus (IHNV), infectious pancreatic necrosis virus (IPNV), and Oncorhynchus masou virus (OMV) using plaque reduction in CHSE-214 cell lines. Anti viral tests against the shrimp pathogenic virus, yellow-head virus (YHV), was carried out using the injection method. The efficacy of guava extract was also determined using MIC of the extract against 24 strains of pathogenic bacteria including; Vibrio harveyi (9 strains), V. splendidus (7 strains), V. parahaemolyticus (2 strains) and 1 strain of each V. mimicus, V. vulnificus, V. fluvialis, V. chorelae, V. alginolyticus and Aeromonas hydrophila. A toxicity test of the extract was performed with CHSE-214 cell lines and post larvae 15 of black tiger shrimp (Penaeus monodon). The efficacy of guava extract for the prevention of viral disease and bacterial disease in aquatic animals was estimated using YHV infection in black tiger shrimp and A. hydrophila infection in catfish, respectively. The extract of guava demonstrated anti viral activity against IHNV, OMV and YHV but was not effective for IPNV. Furthermore, the MIC of the extract ranged from 625 - 5,000 μg/ml against all pathogenic bacterial strains tested. The 50% cytotoxicity of the extract to CHSE-214 was 1,923 μg/ml while the LD50 of the extract to black tiger shrimp post larvae was 2,968 ± 3.8 μg/ml. These results show that guava extract has low toxicity to salmon cell lines and black tiger shrimp. Moreover, the extract is effective for prevention of bacterial infection in catfish (Clarias macrocephalus) while not suitable for prevention of yellow-head virus infection in black tiger shrimp. From these results, guava can be recommended for treatment of bacterial disease in fish. The route of administration and effective dose should be determined before their efficacy can be tested in field trials.Third Symposium on Diseases in Asian Aquaculture. 1996. Bangkok, Thailand