Diseases of Aquatic Organisms 

About: Diseases of Aquatic Organisms is an academic journal published by Inter-Research. The journal publishes majorly in the area(s): Population & Salmo. It has an ISSN identifier of 0177-5103. Over the lifetime, 4166 publications have been published receiving 147270 citations. The journal is also known as: DAO. Diseases of aquatic organisms (Print) & DAO. Diseases of aquatic organisms (Internet).

Rapid quantitative detection of chytridiomycosis (Batrachochytrium dendrobatidis) in amphibian samples using real-time Taqman PCR assay.

Abstract: Batrachochytrium dendrobatidis is a major pathogen of frogs worldwide, associated with declines in amphibian populations. Diagnosis of chytridiomycosis to date has largely relied upon histological and immunohistochemical examination of toe clips. This technique is invasive and insensitive particularly at early stages of infection when treatment may be possible. We have developed a real-time PCR Taqman assay that can accurately detect and quantify one zoospore in a diagnostic sample. This assay will assist the early detection of B. dendrobatidis in both captive and wild populations, with a high degree of sensitivity and specificity, thus facilitating treatment and protection of endangered populations, monitoring of pristine environments and preventing further global spread via amphibian trade.

Diagnostic assays and sampling protocols for the detection of Batrachochytrium dendrobatidis

Abstract: Batrachochytrium dendrobatidis is a fungus belonging to the Phylum Chytridiomycota, Class Chytridiomycetes, Order Chytridiales, and is the highly infectious aetiological agent responsible for a potentially fatal disease, chytridiomycosis, which is currently decimating many of the world's amphibian populations. The fungus infects 2 amphibian orders (Anura and Caudata), 14 families and at least 200 species and is responsible for at least 1 species extinction. Whilst the origin of the agent and routes of transmission are being debated, it has been recognised that successful management of the disease will require effective sampling regimes and detection assays. We have developed a range of unique sampling protocols together with diagnostic assays for the detection of B. dendrobatidis in both living and deceased tadpoles and adults. Here, we formally present our data and discuss them in respect to assay sensitivity, specificity, repeatability and reproducibility. We suggest that compliance with the recommended protocols will avoid the generation of spurious results, thereby providing the international scientific and regulatory community with a set of validated procedures which will assist in the successful management of chytridiomycosis in the future.

Determination of the infectious nature of the agent of acute hepatopancreatic necrosis syndrome affecting penaeid shrimp

Abstract: A new emerging disease in shrimp, first reported in 2009, was initially named early mortality syndrome (EMS). In 2011, a more descriptive name for the acute phase of the disease was proposed as acute hepatopancreatic necrosis syndrome (AHPNS). Affecting both Pacific white shrimp Penaeus vannamei and black tiger shrimp P. monodon, the disease has caused sig- nificant losses in Southeast Asian shrimp farms. AHPNS was first classified as idiopathic because no specific causative agent had been identified. However, in early 2013, the Aquaculture Pathol- ogy Laboratory at the University of Arizona was able to isolate the causative agent of AHPNS in pure culture. Immersion challenge tests were employed for infectivity studies, which induced 100% mortality with typical AHPNS pathology to experimental shrimp exposed to the pathogenic agent. Subsequent histological analyses showed that AHPNS lesions were experimentally in - duced in the laboratory and were identical to those found in AHPNS-infected shrimp samples col- lected from the endemic areas. Bacterial isolation from the experimentally infected shrimp enabled recovery of the same bacterial colony type found in field samples. In 3 separate immer- sion tests, using the recovered isolate from the AHPNS-positive shrimp, the same AHPNS pathol- ogy was reproduced in experimental shrimp with consistent results. Hence, AHPNS has a bacter- ial etiology and Koch's Postulates have been satisfied in laboratory challenge studies with the isolate, which has been identified as a member of the Vibrio harveyi clade, most closely related to V. parahemolyticus.

White spot syndrome baculovirus (WSBV) detected in cultured and captured shrimp, crabs and other arthropods

Abstract: Whlte spot syndrome baculovirus (WSBV) has been found across ddferent shrimp species and in different Asian countries. The detection of WSBV in shrimp with white spot syndrome has already been achieved by means of l-step polymerase chain reaction (PCR). In an attempt to establish a more sensitive assay, we evaluated the effect of 2-step amplification with nested primers on the sensitivity of WSBV diagnostic PCR. The sensitivity of the 2-step amplification was 10" to 10"imes higher than that of l-step amplification. Using both techniques, we successfully detected WSBV DNA in cultured and captured shrimp, crabs and other arthropods. Cultured Penaeus monodon (black tiger shrimp), P. japonicus (kuruma shrimp), P penicjllatus (red tail shrimp), and Metapenaeus ensis (sand shrimp) displaying white spot syndrome were collected from farms at different localities. One-step amplification of the DNA extracted from these shrimps consistently yielded an expected 1447 bp PCR product. Some of the tested specimens of cultured Scylla serrata (mud crab) that exhibited white spot syndrome were positive in l-step WSBV diagnostic PCR, while others were positive only in 2-step WSBV diagnostic PCR. Use of the 2-step amplification protocol also detected a WSBV-specific DNA fragment in Macrobrachium rosenbergii (the giant freshwater prawn) exhibiting white spot syndrome. We also confirmed that WSBV exists in wild-caught shrimp (P monodon, f! japonicus, P semisulcatus and P penicillatus) and crabs (Charybdisferiatus. Portunuspelagicus and P. sanguinolentus) collected from the natural environment in coastal waters around southern Taiwan. Detection of WSBV in non-cultured arthropods collected from WSBV-affected shrimp farms revealed that copepods, the pest crab Hehce tndens, small pest Palaemonidae prawn and the larvae of an Ephydridae insect were reservoir hosts of WSBV. The relatedness between WSBV and Thailand's systemc ectodermal and mesodermal baculovirus (SEMBV) is d~scussed in this paper.

Pathogenicity of a baculovirus infection causing white spot syndrome in cultured penaeid shrimp in Taiwan

Abstract: Outbreaks of a disease causing serious losses among populations of cultured penaeid shrimp, including Penaeus monodon, P japonicus and P penicillatus, in Taiwan are characterized by obvious white spots on the carapace, appendages and the inside surface of the body. For this reason, we propose the name 'white spot syndrome' (WSS). Healthy juvenile kuruma shrimp P japonjcus were exposed by immersion to epidermal filtrate from diseased P japonicus and L? monodon which exhibited marked white spot signs. These experimentally infected shrimp resembled the spontaneously infected ones. Cumulative mortalities reached 100% within 5 to 7 d and were significantly affected by catching and temperature stress. A non-occluded rod-shaped viral particle was found by electron microscopy in the epidermis of both spontaneously and experimentally infected kuruma shrimp. Virions were enveloped, 330 + 20 nm in length and 87 * 7 nm in diameter. The close resemblance in external signs and viral morphology between spontaneously diseased and experimentally infected shrimp indicated that the rod-shaped virus may be the main causative agent of the disease characterized by white spot syndrome in Taiwan.