ABSTRACT-Three regions of koi herpesvirus (KHV) genomic DNA were compared for 34 samples from Japan, six from Indonesia, two from Taiwan, one from the Philippines, 13 from the Netherlands, one from the UK, one from the USA and one from Israel. The analyzed genomic regions included known PCRdetection targets (SphI-5, 9/5 and the thymidine kinase gene). The KHVs from Asian countries were very homogeneous, although two variants were noted based on a single nucleotide polymorphism. In contrast, seven variants were found in KHVs from outside of Asia, and although closely related to one another, they were clearly distinct from those from Asian. The results suggest that a clear genetic distinction exists between Asian and European (including each single isolate from the USA and Israel) types of KHV, and that unique types of KHV were independently introduced or emerged in the respective geographic locations.

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The sensitivity of Lagenidium spp. isolated from Penaeus monodon and Scylla serrata to 34 antimycotic compounds was determined. Mycostatic effects were evaluated from observations of chemicals on the development of vesicles, zoospores and mycelial growth and on these bases three classes of mycostatic effect were recognized. Zoospores were inhibited by < 1 mg/I of clotrimazole, crystal violet, econazole nitrate, malachite green, treflan and trifluralin; 1-5 mg/l of benzalkonium chloride, daconil, domestic detergent, basic fuchsin and furanace; and 10-50 mg/l beniate, formalin, griseofulvin, phenol and potassium permanganate. Variable mycostatic levels, however, were exhibited with copper sulphate, 2,4-D, hydrogen peroxide, methylene blue, pimaricin, resiguard and tolnaftate while amphotericin, iodine, nystatin, triacetin, boric acid, fungitox and PVP-iodine proved to be poor antifungal agents.

This is the first report of the isolation and characterization of a fish virus from the Philippines. The virus was isolated using snakehead spleen cells (SHS) from severely lesioned epizootic ulcerative syndrome (EUS)-affected snakehead Ophicephalus striatus from Laguna de Bay, in January 1991. The virus induced cytopathic effects (CPE) in SHS cells yielding a titer of 3.02 × 10 6 TCID 50 ml -1 at 25°C within 2 to 3 d. Other susceptible cell lines included bluegill fry (BF-2), catfish spleen (CFS) and channel catfish ovary (CCO) cells. Replication in chinook salmon embryo cells (CHSE-214) was minimal while Epithelioma papulosum cyprini cells (EPC) and rainbow trout gonad cells (RTG-2) were refractory. Temperatures of 15 to 25°C were optimum for virus replication but the virus did not replicate at 37°C. The virus can be stored at -10 and 8°C for 30 and 10 d, respectively, without significant loss of infectivity. Viral replication was logarithmic with a 2 h lag phase; viral assembly in the host cells occurred in 4 h and release of virus occurred 8 h after viral infection. A 1-log difference in TCID 50 titer between the cell-free virus and the total virus was noted. Freezing and thawing the virus caused a half-log drop in titer. Viral exposure to chloroform or heating to 56°C for 30 min inactivated the virus. Exposure to pH 3 medium for 30 min resulted in a more than 100-fold loss of viral infectivity. The 5-iododeoxyuridine (IUdR) did not affect virus replication, indicating a RNA genome. Neutralization tests using the Philippine virus, the ulcerative disease rhabdovirus (UDRV) and the infectious hematopoietic necrosis virus (IHNV) polyvalent antisera showed slight cross-reaction between the Philippine virus antiserum and UDRV but established no serological relationship with SHRV and IHN virus. Transmission electron microscopy (TEM) of SHS cells infected with the virus showed virus particles with typical bullet morphology and an estimated size of 65 × 175 nm. The Philippine virus was therefore a rhabdovirus, but the present study did not establish its role in the epizootiology of EUS. KEY WORDS: Epizootic ulcerative syndrome (EUS) · Fish rhabdovirus · Characterization · Ophicephalus striatus · Snakehead · Disease · Cell susceptibilityResale or republication not permitted without written consent of the publisher Dis Aquat Org 43: 191-198, 2000 tius spp., serpent fish Channa spp. and spiny eels Fluta alba (Tonguthai 1985). Outbreaks are more common between the months of September and March, which correlates with the time when lowest water temperatures occur.Several species of bacteria and fungi have been found to be associated with EUS-affected snakeheads Ophicephalus striatus, but these have not been conclusively shown to be the primary disease agents of EUS (Lio-Po et al. 1992, 1996, 1998, Roberts et al. 1993, Callinan et al. 1995. Lilley & Roberts (1997) reported the histological invasiveness of the EUS-associated Aphanomyces through the fish muscles after experimental exposure, but the development o...