Journal of Fish Diseases
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Experimental host range and histopathology of white spot syndrome virus (WSSV) infection in shrimp, prawns, crabs and lobsters from India Experimental studies were conducted by injecting or feeding white spot syndrome virus (WSSV) derived from infected shrimp, Penaeus monodon (Fabricius), collected from the south‐east coast of India, to five species of shrimp, two species of freshwater prawns, four species of crabs and three species of lobsters. All species examined were susceptible to the virus. Experimental infections in the shrimp had the same clinical symptoms and histopathological characteristics as in naturally infected P. monodon . A cumulative mortality of 100% was observed within 5–7 days in shrimp injected with WSSV and 7–9 days in shrimp fed with infected tissue. Two species of mud crab, Scylla sp., survived the infection for 30 days without any clinical symptoms. All three species of lobsters, Panulirus sp., and the freshwater prawn, Macrobrachium rosenbergii (De Man), survived the infection for 70 days without clinical symptoms. However, bioassay and histology using healthy P. monodon revealed that crabs, prawns and lobsters may act as asymptomatic carriers/reservoir hosts of WSSV. This is the first report to suggest the carrier/reservoir capacity of these hosts through histological and bioassay evidences. Ultrastructural details of the virus in experimentally infected shrimp, P. vannamei , (Boone), were also studied.
Journal of Fish Diseases - Tập 22 Số 3 - Trang 183-191 - 1999
Experimental infection of European crustaceans with white spot syndrome virus (WSSV) Eight European marine and freshwater crustaceans were experimentally infected with diluted shrimp haemolymph infected with white spot syndrome virus (WSSV). Clinical signs of infection and mortalities of the animals were routinely recorded. Diagnosis was by direct transmission electron microscopy (TEM), DNA hybridization (dot‐blot and in situ hybridization) using WSSV probes and by PCR using WSSV specific primers. High mortality rates were noted between 7 to 21 days post‐infection for Liocarcinus depurator , Liocarcinus puber , Cancer pagurus , Astacus leptodactylus , Orconectes limosus , Palaemon adspersus and Scyllarus arctus . Mortality reached 100%, 1 week post‐infection in P. adspersus . When infection was successful, direct TEM observation of haemolymph revealed characteristic viral particles of WSSV, some observed as complete virions (enveloped), others as nucleocapsids associated with envelope debris. WSSV probes showed strong positive reactions in dot‐blots and by in situ hybridization in sections and specific virus DNA fragments were amplified successfully with WSSV primers. White spot syndrome virus was pathogenic for the majority of the crustaceans tested. This underlines the epizootic potential of this virus in European crustaceans.
Journal of Fish Diseases - Tập 24 Số 7 - Trang 377-382 - 2001
Quantification of Flavobacterium psychrophilum in rainbow trout, Oncorhynchus mykiss (Walbaum), tissues by qPCR
Journal of Fish Diseases - Tập 34 Số 11 - Trang 811-821 - 2011
<i>Flavobacterium psychrophilum</i> infections in salmonid fish Abstract Flavobacterium psychrophilum is the causative agent of bacterial cold water disease and rainbow trout fry syndrome, disease entities responsible for substantial economic losses in salmonid aquaculture. Problems associated with epizootics include high mortality rate, increased susceptibility to other diseases, high labour costs of treatment and the enormous expenditure on chemotherapy. Despite the increasing significance of the disease, the pathogenesis of F. psychrophilum infections has only been partially elucidated, hampering the development of preventive measures to efficiently combat this disease condition. This literature review discusses the agent and the disease it causes, with emphasis on the bacterium–host interactions.
Journal of Fish Diseases - Tập 26 Số 10 - Trang 563-574 - 2003
Phenotypic, serological and genetic characterization of <i>Flavobacterium psychrophilum</i> strains isolated from salmonids in Chile Abstract Characterization of 20 Flavobacterium psychrophilum strains isolated from farmed Atlantic salmon and rainbow trout in Chile was done using phenotypic, antigenic and genetic techniques. Experimental infections were also performed to assess the virulence of two representative isolates and of the type strain. Biochemical and physiological analyses showed that Chilean F. psychrophilum strains, regardless of the host species, constitute a phenotypically very homogeneous group matching with previous descriptions of this pathogen. However, serological assays indicated the existence of antigenic heterogeneity with four patterns of serological reactions. The first group contained most (14 of 20) of the F. psychrophilum isolates showing cross‐reaction with the antisera obtained against Atlantic salmon and rainbow trout isolates. Group 2 corresponded to four other rainbow trout isolates (1658, 1731, 1762 and 29009) that did not agglutinate with anti‐1150 serum. Two minor serological groups were identified for the remaining isolates (Groups 3 and 4). Marked homogeneity was also revealed by genetic studies including 16S rRNA alleles, random amplified polymorphic DNA and REP‐PCR showing that a major genetic group of F. psychrophilum may be dominant in disease outbreaks in farms. Restriction fragment length polymorphism of PCR analysis showed that gyrase genotypes B‐S or B‐R were found in Chilean isolates from rainbow trout and Atlantic salmon, whereas genotype A was not found. Virulence assays using Atlantic salmon indicated no relationship between the degree of pathogenicity and the host origin of the F. psychrophilum strains.
Journal of Fish Diseases - Tập 32 Số 4 - Trang 321-333 - 2009
Influence of rearing conditions on <i>Flavobacterium columnare</i> infection of rainbow trout, <i>Oncorhynchus mykiss</i> (Walbaum) Abstract The influence of rearing conditions on Flavobacterium columnare infection of rainbow trout, Oncorhynchus mykiss (Walbaum), was studied experimentally in the laboratory and at a fish farm. In experiment I, the effect of parasitic infection on columnaris disease was studied using F. columnare carrier fish. The fish were exposed to Diplostomum spathaceum cercariae and a set of other stressors in order to induce clinical columnaris infection. Parasitic infection and other stressors failed to induce the disease. Disease occurred when the fish were challenged with F. columnare , but D. spathaceum infection did not enhance the severity of the infection. In experiment II, the influence of rearing density and water temperature was studied. Overall mortality was highest in fish at normal rearing density with high temperature (+23 °C). At low temperature (+18 °C) mortality was not affected by rearing density, but the transmission of columnaris disease was faster at normal rearing density at both temperatures. This supports the view that reduction of fish density could be used in prevention of columnaris disease especially if water temperature is high. Because the lower rearing density can also decrease the transmission of ectoparasites and penetrating endoparasites, it could be an efficient tool in ecological disease management.
Journal of Fish Diseases - Tập 28 Số 5 - Trang 271-277 - 2005
Priming the immune system of Penaeid shrimp by bacterial <scp>HSP</scp>70 (DnaK) Abstract This study was conducted to test the effect of DnaK on priming immune responses in Penaeid shrimp. Juvenile‐specific pathogen‐free (SPF ) P. vannamei shrimp were injected with 0.05 μg recombinant DnaK. One hour post‐DnaK priming, a non‐lethal dose of Vibrio campbellii (105 CFU shrimp−1 ) was injected. Other treatments include only DnaK or V. campbellii injection or control with blank inocula. The haemolymph of three shrimp from each treatment was collected at 1.5, 6, 9 and 12 h post‐DnaK priming (hpp). It was verified that injection with DnaK and V. campbellii challenge affected the transcription of 3 immune genes, transglutaminase‐1 (TG ase‐1), prophenoloxidase‐2 (proPO ‐2) and endogenous HSP 70 (lvHSP 70). In P. monodon , shrimp were first injected with DnaK at a dose of 10 μg shrimp−1 and one hour later with 106 CFU of V. harveyi (BB 120) shrimp−1 . Shrimp injected with DnaK showed a significant increase in proPO expression compared to the control (P < 0.05). Yet a double injection (DnaK and Vibrio ) seemed to cause an antagonistic response at the level of expression, which was not equalled at the level of PO activity. Those results suggest that DnaK is able to modulate immune responses in P. vannamei and P. monodon .
Journal of Fish Diseases - Tập 39 Số 5 - Trang 555-564 - 2016
Histopathology of <i>Edwardsiella ictaluri</i> in channel catfish, <i>Ictalurus punctatus</i> (Rafinesque)*
Journal of Fish Diseases - Tập 8 Số 4 - Trang 389-392 - 1985
Histopathology in fish: proposal for a protocol to assess aquatic pollution Water pollution induces pathological changes in fish. As an indicator of exposure to contaminants, histology represents a useful tool to assess the degree of pollution, particularly for sub‐lethal and chronic effects. However, a standardized method for the description and assessment of histological changes, mainly for use in freshwater fish, is still lacking. In this paper, the present authors propose a standardized tool for the assessment of histological findings which can be applied to different organs. The methodology is based on two factors: (1) the extension of a pathological change is rated with a ‘score value’; and (2) the pathological importance of this alteration is defined as an ‘importance factor’. The sum of the multiplied score values and importance factors of all diagnosed changes results in different indices. With these indices, statistical analysis can be carried out. Assessment methods for the gills, liver, kidney and skin are described.
Journal of Fish Diseases - Tập 22 Số 1 - Trang 25-34 - 1999
Cyanobacterial (blue‐green algal) bloom associated pathology in brown trout, <i>Salmo trutta</i> L., in Loch Leven, Scotland
Journal of Fish Diseases - Tập 17 Số 2 - Trang 177-181 - 1994
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