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A two tube, nested PCR detection method for AHPND bacteria - News

A two tube, nested PCR detection method for AHPND bacteria - News | Aquaculture Directory | Scoop.it

A new method for the detection of AHPND bacteria AP4 has been published. The advantage of the AP4 method over the previously published AP3 method is that the it has 100 times higher sensitivity. Because of its higher sensitivity, the bacterial culture enrichment step needed when using the AP3 with low levels of AHPND bacteria may be omitted. However, the AP4 method should not be considered as a replacement for the AP3 method but simply as an alternative choice for the users to choose should they need a more sensitive detection method.

 

The AP4 PCR method was developed entirely by Thai scientists working in Thailand at Centex Shrimp,the Shrimp-virus interaction laboratory, BIOTEC and Aquatic Animal Health Research Center and Charoen Pokphand Co. Ltd. It was also supported entirely by research funding from Thailand. 


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John Bostock's curator insight, March 10, 6:13 AM

Sorry - a little late spotting and publishing this.

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Optimisation and standardisation of functional immune assays for striped catfish (Pangasianodon hypophthalmus) to compare their immune response to live and heat killed Aeromonas hydrophila as model...

Optimisation and standardisation of functional immune assays for striped catfish (Pangasianodon hypophthalmus) to compare their immune response to live and heat killed Aeromonas hydrophila as model... | Aquaculture Directory | Scoop.it

Aquaculture production of Pangasianodon hypophthalmus is growing rapidly in South East Asia, especially in Vietnam. As it is a relatively new aquaculture species there are few reports evaluating its immune response to pathogens. Thus, functional assays for P. hypophthalmus were optimised to evaluate both innate and adaptive immune responses, and were then used to examine immune response following stimulation with live and heat-killed Aeromonas hydrophila. These were used as models of infection and vaccination, respectively.

Four treatment groups were used, including a control group, a group injected intraperitonally (IP) with adjuvant only, a group injected with heat-killed A. hydrophila (1 × 109 cfu ml−1 mixed with adjuvant), and a group injected with a subclinical dose of live A. hydrophila. Samples were collected at 0, 1, 3, 7, 14 and 21 days post-injection (d.p.i.) to assess their immune response. The results indicated that challenge with live or dead bacteria stimulated the immune response in P. hypophthalmus significantly above the levels observed in control groups with respect to specific antibody titre, plasma lysozyme and peroxidase activity, and phagocytosis by head kidney macrophages at 7 or/and 14 d.p.i. At 21 d.p.i., total and specific antibody (IgM) levels and plasma lysozyme activity in fish injected with either live or dead A. hydrophila were significantly different to the control groups. Differential immune responses were observed between fish injected with either live or dead bacteria, with live A. hydrophila significantly stimulating an increase in WBC counts and plasma peroxidase activity at 3 d.p.i., with the greatest increase in WBC counts noted at 21 d.p.i. and in phagocytosis at 14 d.p.i. By 21 d.p.i. only the macrophages from fish injected with dead A. hydrophilashowed significantly stimulation in their respiratory burst activity. This study provides basic information on the immune response in pangasius catfish that can be useful in the health control of this species.

 (Wanna Sirimanaponga, Kim D. Thompsona, Kan Kledmaneeb, Prawporn Thaijongrakb, Bertrand Collet, Ei Lin Ooi & Alexandra Adams IN  Fish & Shellfish Immunology, 40(2) 374-383 - October 2014).


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John Bostock's curator insight, August 13, 2014 8:24 AM

Excellent article from Dr Sirimanapong and colleagues available on open access until October 2014.

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Edwardsiellosis in farmed turbot, Scophthalmus maximus (L.), associated with an unusual variant of Edwardsiella tarda

Edwardsiellosis in farmed turbot, Scophthalmus maximus (L.), associated with an unusual variant of Edwardsiella tarda | Aquaculture Directory | Scoop.it

During 2005 and 2010, a survey of edwardsiellosis on eight turbot, Scophthalmus maximus (L.), farms was conducted in China. This report presents the detailed results of the study on this disease. Diseased turbot displayed two distinct types of gross signs: black discoloration of the dorsal skin on the posterior portion of the body; and red cutaneous foci on the ventral side. Internally, the most pronounced clinical signs in all fish examined were enlarged kidneys. The causal agent of the disease was finally proved to be one species of bacterium that was identified as Edwardsiella tarda by physiological and biochemical tests, API 32E and 16S ribosomal RNA sequence analysis. It is noteworthy that unlike the commonly described E. tarda strains, the isolates in this study were non-motile strains without flagella. A histopathological study revealed that E. tarda infection was systemic in turbot and that kidney showed the most significant pathological changes, including acute focal necrosis, an influx of macrophages and formation of granuloma. The most common histopathological characteristics of this disease are the proliferation of macrophage in various organs and formation of granuloma. In addition, this article also gave background information on the disease and presented the results of virulence tests with theE. tarda strain identified in this study.


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Novel insights into the peritoneal inflammation of rainbow trout (Oncorhynchus mykiss)

Novel insights into the peritoneal inflammation of rainbow trout (Oncorhynchus mykiss) | Aquaculture Directory | Scoop.it

The peritoneal cavity has been extensively used as a laboratory model of inflammation in many species, including the teleost fish. Although, the peritoneal cavity of rainbow trout (Oncorhynchus mykiss) was previously shown to contain a resident population of leukocytes, closer information about their exact composition and their functional response to pathogens is still missing. In the presented work, flow cytometric analysis using monoclonal antibodies was performed to characterize this cell population and evaluate its traffic during the first 72 h after antigenic stimulation and infection with Aeromonas salmonicida. Obtained results indicate that the unstimulated peritoneal cavity represents rather a lymphoid niche, dominated by the IgM+ B cells. Expectedly, the composition changed rapidly after stimulation, which resulted in two complete changes of dominant cell type within first 72 h post injection. While the first stage of inflammation was dominated by myeloid cells, lymphocytes predominated at the later time points, with IgM+B cells representing more than two thirds of all cells. Later, the infection experiment elucidated the peritoneal infection and identified the key differences to the antigenic stimulation. Additionally, the data indicate that the resolution of the inflammation depends more on the bacterial clearance by myeloid cells than on regulation by lymphocytes. Taken together, obtained results represent the first complete description of the immune reaction protecting the peritoneal cavity of the fish and shed some light on the conservation of these processes during the evolution.


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MSD Animal Health Develops New Fish Vaccine Against Most Prevalent Disease Affecting Tilapia

MSD Animal Health Develops New Fish Vaccine Against Most Prevalent Disease Affecting Tilapia | Aquaculture Directory | Scoop.it
GLOBAL - MSD Animal Health (known as Merck Animal Health in the USA and Canada) has introduced a new fish vaccine as a promising measure to help protect tilapia and other fish against the biotype 1 strain of Streptococcus agalactiae, which is the biotype specific to Thailand and other key tilapia-producing regions in Asia, including Malaysia.

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John Bostock's curator insight, January 17, 7:09 AM

Good to see all the research efforts now translated to a marketed product that should make a real difference for the industry.

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Atypical furunculosis (Aeromonas salmonicida atypical) in Atlantic salmon (Salmo salar), Case 2013-2014: Macroscopic Pathology

Atypical furunculosis (Aeromonas salmonicida atypical) in Atlantic salmon (Salmo salar), Case 2013-2014: Macroscopic Pathology | Aquaculture Directory | Scoop.it

Atypical Furunculosis is a bacterial infection caused by Aeromonas salmonicidaatypical in Chile affecting the Atlantic salmon ( Salmo salar ) in the growth phase in freshwater and seawater. The first record of the disease in Chile was described in 1995 (Bravo, 2000).

 

The macroscopic clinical signs correspond to hemorrhagic septicemia, should be deemed as a differential diagnosis in bacterial and viral hemorrhagic diseases


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John Bostock's curator insight, January 29, 2014 8:37 AM

Another sample pathology blog from Marcos Godoy (use translation engine if you don't read Spanish)

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A new species of the fish pathogenic bacterium Edwardsiella - NVH

A new species of the fish pathogenic bacterium Edwardsiella - NVH | Aquaculture Directory | Scoop.it

Takele Abayneh Tefera's doctoral research project has uncovered a genetic divergence between the fish pathogen Edwardsiella tarda and Edwardsiella tarda type strain. He has also identified phenotypic markers that distinguish one from the other. The fish pathogenic strain is now classified as a separate species: Edwardsiella piscicida.

 

 

Edwardsiella tarda is a bacterium that can infect a number of animal species and also humans. Edwardsiellosis is one of the most serious systemic bacterial diseases in fish, resulting in substantial losses in the fish farming industry all over the world.

 

Takele Abayneh Tefera has developed effective molecular tools for the identification and characterization of different strains of Edwardsiella. He developed a new TaqMan real-time and conventional PCR analysis for this purpose and then evaluated it in relation to the Loop Mediated Isothermal Amplification (LAMP) analysis. For the first time, he also used the Multi-locus Sequence Analysis (MLSA) for the typing and characterization of E. tarda, isolated from different sources. This is a useful tool for detecting sources of infection and for understanding the epidemiological relationship between isolates from the environment, fish, livestock and humans.


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