Salmon Gill Poxvirus, the Deepest Representative of the Chordopoxvirinae.

UNLABELLED: Poxviruses are large DNA viruses of vertebrates and insects causing disease in many animal species, including reptiles, birds, and mammals. Although poxvirus-like particles were detected in diseased farmed koi carp, ayu, and Atlantic salmon, their genetic relationships to poxviruses were not established. Here, we provide the first genome sequence of a fish poxvirus, which was isolated from farmed Atlantic salmon. In the present study, we used quantitative PCR and immunohistochemistry to determine aspects of salmon gill poxvirus disease, which are described here. The gill was the main target organ where immature and mature poxvirus particles were detected. The particles were detected in detaching, apoptotic respiratory epithelial cells preceding clinical disease in the form of lethargy, respiratory distress, and mortality. In moribund salmon, blocking of gas exchange would likely be caused by the adherence of respiratory lamellae and epithelial proliferation obstructing respiratory surfaces. The virus was not found in healthy salmon or in control fish with gill disease without apoptotic cells, although transmission remains to be demonstrated. PCR of archival tissue confirmed virus infection in 14 cases with gill apoptosis in Norway starting from 1995. Phylogenomic analyses showed that the fish poxvirus is the deepest available branch of chordopoxviruses. The virus genome encompasses most key chordopoxvirus genes that are required for genome replication and expression, although the gene order is substantially different from that in other chordopoxviruses. Nevertheless, many highly conserved chordopoxvirus genes involved in viral membrane biogenesis or virus-host interactions are missing. Instead, the salmon poxvirus carries numerous genes encoding unknown proteins, many of which have low sequence complexity and contain simple repeats suggestive of intrinsic disorder or distinct protein structures. IMPORTANCE: Aquaculture is an increasingly important global source of high-quality food. To sustain the growth in aquaculture, disease control in fish farming is essential. Moreover, the spread of disease from farmed fish to wildlife is a concern. Serious poxviral diseases are emerging in aquaculture, but very little is known about the viruses and the diseases that they cause. There is a possibility that viruses with enhanced virulence may spread to new species, as has occurred with the myxoma poxvirus in rabbits. Provision of the first fish poxvirus genome sequence and specific diagnostics for the salmon gill poxvirus in Atlantic salmon may help curb this disease and provide comparative knowledge. Furthermore, because salmon gill poxvirus represents the deepest branch of chordopoxvirus so far discovered, the genome analysis provided substantial insight into the evolution of different functional modules in this important group of viruses.

Changes in gene expression of gastric mucosa during therapeutic acid inhibition.

BACKGROUND: Long-term therapy with potent acid inhibitors is a common treatment for gastro-esophageal reflux disease. Administration of proton pump inhibitors (PPIs) causes profound and continuous hypochlorhydria by inhibition of the proton pump in gastric parietal cells. Long-term hypergastrinaemia increases mucosal thickness and enterochromaffin-like cell density in oxyntic mucosa. OBJECTIVE: The aim of this study was to see whether this very common clinical intervention induces significant changes in the gastric mucosal gene expression pattern. METHODS: Seven patients suffering from gastro-esophageal reflux disease were included in this study. Endoscopic biopsies were taken from the corpus mucosa before and toward the end of a 3-month treatment with the PPI esomeprazole. RESULTS: Microarray analysis identified 186 differentially expressed genes. A high proportion of genes with changed gene expression levels during PPI treatment are involved in proliferation, apoptosis, and stress response. CONCLUSION: This study identified many genes that were not previously known to be affected by inhibition of gastric acid secretion. Further characterization of the functional roles of genes whose expression is modulated by potent acid inhibition may give new insight into the biological responses to potent acid inhibition, including the mucosal response to the moderately increased gastrin levels encountered in clinical practice.

Sensitivity of Atlantic salmon (Salmo salar) to dietary endosulfan as assessed by haematology, blood biochemistry, and growth parameters.

The presence of the organochlorine pesticide endosulfan in the water column confers a significant direct risk to the biota therein, yet relatively little is known regarding the toxic impact of dietborne endosulfan to aquatic organisms. Pre-smolt Atlantic salmon (Salmo salar) were fed at levels of technical endosulfan equal to the European Union regulatory limit (5 microg kg(-1)) and at levels 10 and 100 times greater, for a total of 49 days with haematology (e.g. erythrocyte count, haemoglobin, haematocrit, white blood cell composition), blood biochemistry (e.g. serum aminotransferase, plasma ions) and growth parameters (e.g. condition factor) recorded at days 0, 14, 35, and 49. Toxicological assessment of the individual alpha and beta-isomers that comprise technical endosulfan was also attempted. No mortality was observed in any group during the experiment. In the groups exposed to the control, 5, and 50 microg kg(-1) technical endosulfan feeds no significant alterations in any measured parameters were determined at any time point. No differences were observed between the technical mixture and the individual alpha and beta-isomer treatment groups. Condition factor was significantly reduced in fish exposed to 500 microg kg(-1) at day 49, while haematocrit, haemoglobin and mean corpuscular haemoglobin were significantly elevated after 35 days of exposure to the same dietary level, but returned to control levels by day 49. The present study shows that with regards to acute toxicity, Atlantic salmon are able to tolerate dietary technical endosulfan levels up to 500 microg kg(-1).