1,720,974 research outputs found
Redspotted Grouper Nervous Necrosis Virus and the Reassortant RGNNV/SJNNV In Vitro Susceptibility against a Commercial Peroxy-Acid Biocide under Different Conditions of Use
Full text linkAquaculture is a constantly growing sector. The intensification of fish production and the movement of aquatic animals could cause the spread of infectious diseases. Remarkably, the diffusion of viral agents represents the major bottleneck for finfish production, and viral encephalopathy and retinopathy (VER) is considered the most impacting disease for Mediterranean aquaculture. No effective therapies are available to contrast VER, and vaccination can be applied only in grow-out facilities. Hence, programs to minimize the sanitary risks in farms are paramount to implementing hygienic standards and biosecurity. This study aimed to evaluate the in vitro virucidal activity of a peroxy-acid disinfectant (Virkon® S, DuPont, Sudbury, UK) towards the two NNV strains most widespread in the Mediterranean Sea. Remarkably, two protocols were applied to assess the virucidal activity under different conditions of use: the suspension test and the net test. The latter has been applied to evaluate the efficacy of the biocide on instruments, simulating the in-field application. The obtained results demonstrated the suitability of the tested biocide for NNV inactivation, being effective under some of the tested conditions. However, the presence of organic matter, the concentration of the product, and the application conditions can significantly affect the result of the disinfection procedure
Advances in Viral Aquatic Animal Disease Knowledge: The Molecular Methods’ Contribution
Full text linkAquaculture is the fastest-growing food-producing sector, with a global production of 122.6 million tonnes in 2020. Nonetheless, aquatic animal production can be hampered by the occurrence of viral diseases. Furthermore, intensive farming conditions and an increasing number of reared fish species have boosted the number of aquatic animals’ pathogens that researchers have to deal with, requiring the quick development of new detection and study methods for novel unknown pathogens. In this respect, the molecular tools have significantly contributed to investigating thoroughly the structural constituents of fish viruses and providing efficient detection methods. For instance, next-generation sequencing has been crucial in reassignment to the correct taxonomic family, the sturgeon nucleo-cytoplasmic large DNA viruses, a group of viruses historically known, but mistakenly considered as iridoviruses. Further methods such as in situ hybridisation allowed objectifying the role played by the pathogen in the determinism of disease, as the cyprinid herpesvirus 2, ostreid herpesvirus 1 and betanodaviruses. Often, a combination of molecular techniques is crucial to understanding the viral role, especially when the virus is detected in a new aquatic animal species. With this paper, the authors would critically revise the scientific literature, dealing with the molecular techniques employed hitherto to study the most relevant finfish and shellfish viral pathogens
Detection of Human and Fish Viruses in Marine Gastropods
Full text linkSIMPLE SUMMARY: Mollusca is one of the largest phyla in the animal kingdom that includes more than 100,000 existing species living in aquatic and terrestrial habitats. Within this phylum, marine molluscs are considered an important resource for fisheries, and gastropods represent 2% of marine molluscs fished worldwide. Similar to bivalves, gastropods are susceptible to environmental contamination, and they are able to accumulate microorganisms. However, despite their economic importance, only few studies have focused on the monitoring of viral contamination in their tissues and their possible role as carriers. In this study, the presence of human pathogenic viruses such as hepatitis A virus, but not noroviruses, different to the situation in bivalve molluscs, was found in gastropods. This finding suggests a low risk of food-borne viral infections for gastropod consumers. Furthermore, one of the most impactful pathogens for marine aquaculture, nervous necrosis virus (NNV), was detected in gastropods. However, the animal tissues examined did not show any histological changes, suggesting the absence of a pathogenic effect of NNV in the analyzed gastropods. ABSTRACT: Marine gastropods represent a major food source for higher trophic levels and an important source of animal protein for humans. Like bivalve molluscs, gastropods can accumulate several types of contaminants; however, the bioaccumulation of microorganisms, particularly viruses, has been poorly investigated in these animals. This study focused on gastropods (Tritia mutabilis, Bolinus brandaris and Rapana venosa) collected during the fishing season from 2017 to 2021 in the north-western Adriatic Sea, and on clams (Ruditapes philippinarum) harvested in the same geographical area, in order to evaluate the presence of human and fish viruses in their tissues. A virological investigation was carried out on the digestive gland using molecular methods. The presence of hepatitis A virus was detected in one sample, whereas noroviruses were not present in the investigated specimens. Regarding fish viruses, it was possible to detect the presence of nervous necrosis virus (NNV) in 26.5% of the analyzed gastropods; however, the histological examination did not show any pathological changes in the nervous tissue in both NNV-positive and -negative batches. As a whole, the investigated gastropods showed the ability to bioaccumulate viruses; however, lower contamination by human viruses compared to bivalve molluscs was pointed out, posing a minor concern to human health
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Full text linkIn an adult male goldfish (Carassius auratus, Linnaeus), an unusual combination of diseases was detected. The owner noted a bilateral, asymmetrical distention of the abdomen, multiple cutaneous masses and an altered swimming behaviour over the course of time; diagnostic work-up was not requested and euthanasia elected. Grossly, the cutaneous masses were whitish, discrete, extremely friable. Histologically, the dermis was multifocally expanded by moderately cellular, unencapsulated neoplastic tissue, composed of dermal spindle cells. The celomic cavity opening revealed a gelatinous multicystic mass, corresponding to the kidney, which replicated several cysts compressing the residual parenchyma. Histologically, sparse, late-stage granulomas, basophilic intratubular deposits and crystals were also detected. No mycobacterial DNA was detected in tissue with granulomas. No parasites were detected in the histological sections examined. Diagnoses of cutaneous nerve sheath tumours, polycystic kidney disease, renal late-stage granulomas, nephrocalcinosis and crystals were formulated. The authors had proposed to recapitulate each single condition
Microbiological and pathological findings in koi carp (Cyprinus carpio) affected by swim bladder flooding
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First report of megalocytivirus in ornamental fish in Italy
No full textIntroduction: The trade in marine ornamental fish is a multi-billion-dollar industry involving over 50 exporting and importing countries. Europe is one of the three major importers of marine ornamental fish, along with the United States and Japan. Megalocytiviruses are associated with severe mortality in ornamental fish aquaculture, including both freshwater and marine species. The international trade in live ornamental fish has aided the spread of these viruses. So far, megalocytiviruses have been detected in few European countries (Belgium and Germany), but, to the best of our knowledge, they have never been detected in Italy.
Methodology: In the context of a health surveillance programme on imported ornamental fish, histological lesions consistent with megalocytivirus infection were pointed out in two fish dead during the quarantine period. Case 1# referred to one neon damselfish (Pomacentrus coelestis) out of 10 subjects involved in a 100% mortality event in June 2018, whereas Case 2# was a prickly leatherjacket (Chaetodermis penicilligerus) dead after showing lethargic behaviour in June 2021. To investigate the presence of the megalocytivirus genome, FFPE tissue samples, including the areas with enlarged cells, were subjected to DNA extraction and PCR/real-time PCR analysis using two protocols previously described. PCR products were sequenced and subjected to phylogenetic analysis.
Results: The histological investigation showed in both species the presence in the kidney, spleen, liver, heart, gills, intestine of multiple hypertrophic cells containing granular to smudgy basophilic intracytoplasmic inclusions. Often, these cells were clearly endothelial cells. The presence of megalocytivirus DNA was pointed out in the two fish samples resulting positive to the real-time PCR and being identified as megalocytiviruses. Phylogenetic analysis of a fragment of the MCP gene from Case 2# showed its clustering within the RSIV-like group.
Conclusions: The presence of megalocytivirus was pointed out in imported marine ornamental fish for the first time in Italy. The viral DNA was detected in Pomacentrus coelestis and Chaetodermis penicilligerus, two marine ornamental species that, so far, have never been associated with megalocytivirus infection. Due to the high risk of importing megalocytiviruses through the ornamental fish trade, a strengthening of the surveillance programmes and quarantine measures is recommended
Verrucous epidermal hyperplasia on pectoral fin of a wels catfish (Silurus glanis, Linnaeus 1758)
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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