The ability of the “green water” grow-out culture of the tiger shrimp
Penaeus monodon to prevent outbreaks of Luminous Vibriosis was investigated by screening associated isolates of bacteria, fungi, ...phytoplankton and fish skin mucus for anti-luminous
Vibrio metabolites. Among the 85 bacterial isolates tested, 63 (74%) caused +∼+++ inhibition of the
Vibrio harveyi pathogen after 24–48 h co-cultivation. The variation in growth inhibition rates of +, ++, and +++ were demonstrated by 15 (18%), 13 (15%), and 28 (33%) isolates, respectively, 24 h after treatment. Eight bacterial isolates showed consistently sustained maximum inhibition of luminous
Vibrio after 24 to 48 h exposure. The majority of these luminous
Vibrio inhibiting bacterial isolates were obtained from tilapia mucus and gut. In tests with fungi, 4 of 20 (20%) yeast isolates showed intracellular metabolites inhibitory to luminous
Vibrio. Among filamentous fungi, 5 of 45 (11%) isolates yielded intracellular metabolites while 3 of 41 (7%) isolates had extracellular metabolites inhibitory to luminous
Vibrio. These fungal isolates were identified as
Rhodotorula sp.,
Saccharomyces sp.,
Candida sp.,
Penicillium sp., mycelia sterilia, and two unidentified species. The microalgae,
Chaetoceros calcitrans and
Nitzchia sp., consistently demonstrated complete inhibition of luminous
Vibrio from 24 h and 48 h post exposure, respectively, and during the 7-day experiment.
Leptolyngbia sp. caused a 94–100% reduction of the luminous
Vibrio population from 10
4 to 10
1 cfu/ml 24 h post exposure which was sustained throughout the 10-day observation period. In contrast, the inhibitory effects of
Skeletonema costatum on luminous
Vibrio was bacteriostatic throughout the 7-day exposure while
Nannochlorum sp. did not significantly inhibit luminous
Vibrio. The skin mucus of jewel tilapia,
Tilapia hornorum, had no resident luminous bacteria and inhibited this bacterial pathogen in 6–48 h, which was proportionate to the 10
3 and 10
5 cfu/ml test concentrations of luminous
Vibrio. This study provides a scientific explanation that the effectiveness of the “green water” culture of tiger shrimp (
P. monodon) in preventing outbreaks of luminous Vibriosis among
P. monodon juveniles in grow-out ponds can be attributed to the presence of anti-luminous
Vibrio factors in the bacterial, fungal, phytoplankton microbiota and the skin mucus of tilapia associated with this novel technique of shrimp culture.
Molecular epidemiology of koi herpesvirus Kurita, J.(National Research Inst. of Aquaculture, Tamaki, Mie (Japan). Tamaki Station); Yuasa, K; Ito, T ...
Fish Pathology,
2009, Letnik:
44, Številka:
2
Journal Article
Recenzirano
Odprti dostop
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 PCR-detection targets (Sph1-5, 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.
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 10(6) TCID50 ml(-1) at 25 degrees 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 degrees C were optimum for virus replication but the virus did not replicate at 37 degrees C. The virus can be stored at -10 and 8 degrees 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 degrees 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.
Natural transmission of the epizootic ulcerative syndrome (EUS) was conducted on naïve snakeheads Ophicephalus striatus (also known as Channa striata) kept (A) in aquifer water, (B) in lakewater, (C) ...cohabiting with EUS snakeheads in lakewater, and (D) cohabiting with apparently healthy snakeheads in lakewater during the 1994 to 1995 EUS season. The results showed that EUS-like lesions developed in 6 to 14 d among naïve snakeheads cohabiting with EUS snakeheads and with apparently healthy snakeheads in lakewater (Treatments C and D). Among naïve fish exposed to lakewater (Treatment B), similar lesions developed in 16 to 21 d, while naïve fish in aquifer water (Treatment A) did not develop EUS-like lesions. EUS signs began as Grade I (slight) lesions that gradually progressed to Grades III-IV (severe) 3 to 5 d from lesion onset, similar to the naturally affected EUS fish. The virus was recovered from some but not all naturally EUS-affected snakeheads, snakeheads with healing lesions and apparently healthy snakeheads, but not from naïve snakeheads. The results provide evidence of a waterborne horizontal transmission of the EUS-associated virus. This is the first report of a successful horizontal transmission of the EUS-associated virus from apparently healthy snakeheads to naïve fish under natural conditions and of virus recovery in tissue culture from naturally exposed experimental fish.
Disease due to luminous
Vibrio has been a major problem of the shrimp industry. Different technologies have been introduced to control the disease. One of the techniques reported to work against ...luminous bacteria in the Philippines is the green water culture system (or finfish–shrimp integrated culture system). A green water culture system is an innovative technique wherein shrimp are cultured in water collected from a pond where tilapia or other fish species are grown. In some cases, the fish are cultured in an isolated net pen inside the shrimp culture pond. This study clarifies the effect of one component of the green water culture system, the presence of all male tilapia (
Tilapia hornorum) on luminous bacteria
Vibrio harveyi. Results showed that stocking tilapia at a biomass not lower than 300 g/m
3 efficiently inhibited the growth of luminous bacteria in shrimp (biomass=80 g/m
3) rearing water without the growth of microalgae.
Isolates of Aquaspirillum sp., Pseudomonas sp., and Streptococcus sp. recovered from epizootic ulcerative syndrome (EUS)-affected snakeheads (Ophicephalus striatus) in Thailand as well as an isolate ...of Aeromonas hydrophila recovered from EUS-affected snakeheads in the Philippines were characterized and identified. Each isolate was injected intramuscularly (IM) into healthy catfish (Clarias batrachus) and snakeheads (O. striatus). Results showed in tests with C. batrachus that 24 h after injection, Aquaspirillum sp., Pseudomonas sp., Streptococcus sp. and A. hydrophila induced slight, slight, moderate and severe dermomuscular necrotic lesions, respectively. Among O. striatus, only A. hydrophila induced severe lesions. Streptococcus sp. induced slight lesions 2 days post-injection which healed rapidly, while Aquaspirillum sp. and Pseudomonas sp. did not manifest any dermal lesions. Experiments indicated that among the four EUS-associated test bacteria, A. hydrophila was the most pathogenic, inducing severe dermomuscular necrotic lesions in intramuscularly injected catfish (C. batrachus) and snakeheads (O. striatus). Differences in the susceptibility of O. striatus and C. batrachus to Aquaspirillum sp., Pseudomonas sp. and Streptococcus sp. were evident. Furthermore, this is the first evidence of the association between Aquaspirillum sp. and diseased fish.
Preventing the transboundary movement of fish viral pathogens in a global environment requires active surveillance. This study examined the presence of three emerging viral pathogens among koi, ...common, grass, and silver carp in Cambodia, Lao PDR, Myanmar, Philippines, and Vietnam. The studied viruses included koi herpesvirus (KHV), spring viremia of carp virus (SVCV), and grass carp reovirus (GCRV). Detection methods consisted of virus isolation by cell culture, infection assay in naive fish, polymerase chain reaction (PCR), and reverse-transcriptase PCR (RT-PCR). Tissues were collected and pooled from 193 fish samples in Dec. 2004 to Feb. 2005, 406 in Sep. 2005 to Feb. 2006, and 1302 in Oct. 2006 to Feb. 2007. For cell culture, tissue filtrates were prepared from pooled spleens, kidneys, livers, and gills and inoculated onto koi fin (KF-1), grass carp kidney (GCK), and fat head minnow (FHM) cells. For infection assay, tissue filtrates were injected intraperitoneally to healthy, naive common carp. No virus was detected after three cell culture passages and the infection bioassays. One-step and nested-step PCR was used to detect KHV in gills of fish samples. One-step and semi-nested RT-PCR was used to detect SVCV and GCRV in the spleens, kidneys, and livers of fish samples. Samples from all three years from all five countries yielded negative results for all three viruses, indicating that KHV, SVCV, and GCRV were not present in these five countries during the period of the study although KHV outbreaks had been detected in Indonesia, Taiwan, Japan, Thailand, China, and Malaysia.
This study was conducted to quantify and characterize the mycoflora associated with the 'green water' culture system of Penaeus monodon. Samples of water, tilapia gut and mucus, and shrimp ...hepatopancreas from three shrimp farms were collected during 15, 30, 45 and 60 days of culture (DOC). Results showed that high fungal loads were observed in tilapia gut (total: 117-1352 colony forming unit (CFU) 5 cm hind gut-1; yeasts: 0-136 CFU 5 cm hind gut-1) and mucus (total: 12-311 CFU (5 cm2)-1; yeasts: 0-88 CFU (5 cm2)-1), while minimal fungal populations were observed in water samples (total: 0-110 CFU mL-1; yeasts: 0-5 CFU ml1). Shrimp hepatopancreas harboured a very low number of filamentous fungi (0-27 CFU 0.1 g-1) and yeasts (0-7 CFU 0.1 g-1) especially at 60 DOC. The filamentous fungal isolates were dominated by Penicillium and Aspergillus species, while the yeast populations were dominated by Rhodotorula and Saccharomyces species. The dominance of these fungi on tilapia mucus and gut and their presence in the rearing water might play an important role in the overall mechanisms involved in the control of luminous Vibrio in the 'green water' grow-out culture of P. monodon.
Summary
Isolates of Aquaspirilluni sp., Pseudomonas sp., and Streptococcus sp. recovered from epizootic ulcerative syndrome (EUS)‐affected snakeheads (Ophicephalus striatus) in Thailand as well as an ...isolate of Aeromonas hydrophila recovered from EUS‐affected snakeheads in the Philippines were characterized and identified. Each isolate was injected intramuscularly (IM) into healthy catfish (Clarias batrachus) and snakeheads (O. striatus). Results showed in tests with C. batraclius that 24 h after injection, Aquaspirillum sp., Pseudomonas sp., Streptococcus sp. and A. hydrophila induced slight, slight, moderate and severe dermomuscular necrotic lesions, respectively. Among O. striatus, only A. hydrophila induced severe lesions. Streptococcus sp. induced slight lesions 2 days post‐injection which healed rapidly, while Aquaspirillum sp. and Pseudonionas sp. did not manifest any dermal lesions. Experiments indicated that among the four EUS‐associated test bacteria, A. hydrophila was the most pathogenic, inducing severe dermomuscular necrotic lesions in intramuscularly injected catfish (C. batrachus) and snakeheads (O. striatus). Differences in the susceptibility of O. striatus and C. batrachus to Aquaspirillum sp., Pseudomonas sp. and Streptococcus sp. were evident. Furthermore, this is the first evidence of the association between Aquaspirillum sp. and diseased fish.
Sarotherodon niloticus with average weight of 28.42 +/- 1.87 g were immunized with formalin-killed Edwardsiella tarda using the hyperosmotic infiltration method. Test fish maintained in 30 l aquaria ...were grouped into four treatments. Group 1 and 2 were exposed to a single hyperosmotic treatment on day 0. Group 1 was bled on day 14 and group 2 was bled on day 28. Group 3 was given hyperosmotic treatments twice: on day 0 and day 14 and bled on day 28. Group 4 was an untreated control bled on day 28. All sera were analyzed for agglutinating antibody titer against E. tarda flagellar and somatic antigens. Results showed that flagellar and somatic agglutinin titers in all treatments were not statistically significant. Likewise, infection experiments where test fish were challenged with intraperitoneal injection of the test bacterium showed that the vaccination experiment did not effectively protect the test fish from infection by Edwardsiella tarda.
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