Now showing items 1-3 of 3

    • Article

      Characterization of a virus obtained from snakeheads Ophicephalus striatus with epizootic ulcerative syndrome (EUS) in the Philippines 

      GD Lio-Po, GS Traxler, LJ Albright & EM Leaño - Diseases of Aquatic Organisms, 2000 - Inter Research
      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 x 106 TCID50 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 TCID50 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 x 175 nm. The Philippine virus was therefore a rhabdovirus, but the present study did not establish its role in the epizootiology of EUS.
    • Article

      Experiments on virulence dose and portals of entry for Aeromonas hydrophila in walking catfish 

      GD Lio-Po, LJ Albright & EM Leaño - Journal of Aquatic Animal Health, 1996 - American Fisheries Society
      Aeromonas hydrophila, isolated from chevron snakehead Ophicephalus (=Channa) striatus affected with epizootic ulcerative syndrome (EUS), was injected intramuscularly into healthy walking catfish Clarias batrachus at varying 10-fold serial dilutions from 108 to 0 colony-forming units (cfu) per fish. Only 106 or more cfu/mL induced dermomuscular lesions. Initial healing of lesions was observed by day 7 but complete healing was not apparent until day 16. Experiments were also conducted on possible portals of entry of A. hydrophila into walking catfish: Intramuscular (IM) injection, gastric gavage, fish food, and immersion of injured fish in rearing water inoculated with the test bacteria. Injuries were caused by skin or muscle cut, dermal scraping or incision, fish bite, and cohabitation of fish with golden snails Ampullarius sp. Only IM injection treatment induced dermomuscular pathology in the test catfish. This suggests that a localization of A. hydrophila to a level of 106 cfu/mL in the musculature must be established for dermal lesions to develop.
    • Conference paper

      Studies on the sources of luminescent Vibrio harveyi in Penaeus monodon hatcheries 

      CR Lavilla-Pitogo, LJ Albright, MG Paner & NA Suñaz - In M Shariff, RP Subasinghe & JR Arthur (Eds.), Diseases in Asian Aquaculture I. Proceedings of the First Symposium on Diseases in Asian Aquaculture, 26-29 November 1990, Bali, Indonesia, 1992 - Asian Fisheries Society, Fish Health Section
      One of the major problems in the otherwise highly successful Penaeus monodon hatchery industry in the Philippines is the occurrence of luminescent bacterial disease due to Vibrio harveyi. The possible sources of the bacteria were investigated. Eggs within the ovaries of stage III and IV wild-caught and ablated female P. monodon harbour no bacteria. On the other hand, the midgut contents of these spawners, as well as of pond-reared juveniles, contained numerous luminescent bacteria. Plate counts of the exoskeleton from all sampled females revealed that V. harveyi is a minor component of the exoskeleton-associated flora. Scanning electron microscopy of the exoskeleton showed no significant attached populations. The bacterial loads of Chaetoceros calcitrans, a marine diatom, and Artemia salina nauplii were likewise estimated. C. calcitrans did not harbour V. harveyi at any phase of its growth. Twenty-four-hour-old A. salina appeared to have no resident V. harveyi, but its culture water contained small populations of these bacteria. These data show that the main source of the luminescent bacteria is the midgut contents of the mother, which are shed into the water almost simultaneously with the eggs during spawning.