The first isolation of a flavivirus from fish was made from moribund Chinook salmon (Oncorhynchus tshawytscha) from the Eel River, California, USA. Following the observation of cytopathic effect in a striped-snakehead fish cell line, 35-nm virions with flaviviral morphology were visualized using electron microcopy. Next-generation sequencing and rapid amplification of cDNA ends obtained the complete genome. Reverse transcriptase quantitative PCR (RT-qPCR) confirmed the presence of viral RNA in formalin-fixed tissues from the wild salmon. For the first time, in vivo replication of an aquatic flavivirus was demonstrated following intracoelomic injection in a Chinook salmon model of infection. RT-qPCR demonstrated viral replication in salmon brains up to 15 days postinjection. Infectious virus was then reisolated in culture, fulfilling Rivers’ postulates. Only limited replication occurred in the kidneys of Chinook salmon or in tissues of rainbow trout (Oncorhynchus mykiss). The proposed salmon flavivirus (SFV) has a 10.3-kb genome that encodes a rare dual open reading frame, a feature uncharacteristic of classical flaviviruses. Phylogenetic analysis places SFV in a basal position among a new subgroup of recently recognized aquatic and bat flaviviruses distinct from the established mosquito-borne, tick-borne, insect-only, and unknown-vector flavivirus groups. While the pathogenic potential of the virus remains to be fully elucidated, its basal phylogeny and the in vivo infection model will allow SFV to serve as a prototype for aquatic flaviviruses. Ongoing field and laboratory studies will facilitate better understanding of the potential impacts of SFV infection on ecologically and economically important salmonid species. IMPORTANCE Chinook salmon are a keystone fish species of great ecological and commercial significance in their native northern Pacific range and in regions to which they have been introduced. Threats to salmon populations include habitat degradation, climate change, and infectious agents, including viruses. While the first isolation of a flavivirus from wild migrating salmon may indicate an emerging disease threat, characterization of the genome provides insights into the ecology and long evolutionary history of this important group of viruses affecting humans and other animals and into an expanding group of recently discovered aquatic flaviviruses.

A broadening fish host range is affected by novel and known pigmented fungal pathogens. A review of 2,250 piscine submissions received by the Aquatic Pathology Service, University of Georgia, revealed 47 phaeohyphomycosis cases (2.1%), representing 34 bony and cartilaginous fish species. The majority involved bony fish (45/47, 95.7%) and were predominantly marine (41/47, 87.2%), with only a few freshwater species (4/47, 8.5%). Cartilaginous fish cases included two zebra sharks (Stegostoma fasciatum) (2/47, 4.3%). Northern seahorses (Hippocampus erectus) had the highest incidence overall (7/47, 14.9%). Culture and sequencing of the internal-transcribed spacer region of the rDNA (ITS), large ribosomal subunit gene D1/D2 domains (LSU) and the DNA polymerase II gene (RPB2) were performed for fungal identification when fresh tissue was obtainable. Exophiala, Ochroconis and Neodevriesia spp. were identified, with Exophiala as the most common fungal genus (8/11, 72.7%). Exophiala lecanii-corni and Neodevriesia cladophorae were described for the first time from fish.Microscopically, lesions were characterized by necrosis, granulomatous inflammation and angioinvasion most frequently affecting the skin/fin, skeletal muscle and kidneys. In this study of diverse aquarium-housed fish species, phaeohyphomycosis cases occurred sporadically and in rare outbreaks with variable pathologic presentations, tissue distributions and severities.

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Renal interstitial cell tumor (RICT) is a rare renal sarcoma of dogs that arises from renal interstitial cells. Herein we describe a RICT in an 8-y-old female Labrador Retriever dog that died after a 2-d history of lethargy and disorientation. Grossly, soft white nodules of 1–10 mm diameter were present in the renal cortex and corticomedullary junction of both kidneys, left cardiac ventricular wall, and right cerebral hemisphere. A pale-white to yellow, firm, irregular mass effaced 80% of the right pulmonary parenchyma, involving mainly the cranial and middle lobes, and the adjacent tracheobronchial lymph nodes. Histologically, the renal, myocardial, and cerebral neoplasm consisted of interlacing bundles of stellate-to-spindle cells with eosinophilic vacuolated cytoplasm and round-to-oval nuclei with finely stippled chromatin. The mitotic count was 28 per 2.37 mm2. Alcian blue stain revealed an extracellular myxomatous matrix throughout the neoplasm. Neoplastic cells had cytoplasmic immunolabeling for vimentin and cyclooxygenase 2. The pulmonary and tracheobronchial neoplasm consisted of infiltrative nodules of cuboidal epithelial cells that had a moderate amount of eosinophilic cytoplasm and round nuclei with coarsely stippled chromatin. There were 5 mitoses per 2.37 mm2. Neoplastic cells had cytoplasmic and nuclear immunolabeling for cytokeratin AE1/AE3 and thyroid transcription factor 1, respectively. Morphologic and immunohistochemical findings were consistent with a RICT with cardiac and cerebral metastases, and a pulmonary carcinoma with tracheobronchial lymph node metastasis.

The complete coding sequence of a rotavirus A strain was determined from a dead racing pigeon in Florida. It was found to be most closely related to a rotavirus A strain isolated from a dead racing pigeon in California.