Full-genome sequencing and confirmation of the causative agent of erythrocytic inclusion body syndrome in coho salmon identifies a new type of piscine orthoreovirus

Erythrocytic inclusion body syndrome (EIBS) causes mass mortality in farmed salmonid fish, including the coho salmon, Onchorhynchus kisutchi, and chinook salmon, O. tshawytscha. The causative agent of the disease is a virus with an icosahedral virion structure, but this virus has not been characterized at the molecular level. In this study, we sequenced the genome of a virus purified from EIBS-affected coho salmon. The virus has 10 dsRNA genomic segments (L1, L2, L3, M1, M2, M3, S1, S2, S3, and S4), which closely resembles the genomic organization of piscine orthoreovirus (PRV), the causative agent of heart and skeletal inflammation (HSMI) in Atlantic salmon and HSMI-like disease in coho salmon. The genomic segments of the novel virus contain at least 10 open reading frames (ORFs): lambda 1 (λ1), λ2, λ3, mu 1 (μ1), μ2, μNS, sigma 1 (σ1), σ2, σ3, and σNS. An additional ORF encoding a 12.6-kDa protein (homologue of PRV p13) occurs in the same genomic segment as σ3. Phylogenetic analyses based on S1 and λ3 suggest that this novel virus is closely related to PRV, but distinctly different. Therefore, we designated the new virus ‘piscine orthoreovirus 2’ (PRV-2). Reverse transcription–quantitative real-time PCR revealed a significant increase in PRV-2 RNA in fish blood after the artificial infection of EIBS-naïve fish but not in that of fish that had recovered from EIBS. The degree of anemia in each fish increased as the PRV-2 RNA increased during an epizootic season of EIBS on an inland coho salmon farm. These results indicate that PRV-2 is the probable causative agent of EIBS in coho salmon, and that the host acquires immunity to reinfection with this virus. Further research is required to determine the host range of PRV species and the relationship between EIBS and HSMI in salmonid fish

Comparative Characteristics of the Home Ranges of Domestic and Wild Animals in Arid and Semi-Arid Afro-Eurasian Watering Places as Hot Spots for Pasture Degradation

In this study, we investigated home range of wildlife and livestock that graze on pastures in Mongolia, China (Inner Mongolia and Tibet) and Sudan. In order to clarify the animal home range, the daily movement of domestic and wild animals was tracked using GPS (Global Positioning System) collars and ARGOS satellite transmitters. The home range of sheep, goats and horses was investigated in Mongolia and China; those of camels, donkeys and goats in Sudan; migration of Tibetan antelope (Chiru, Pantholops hodgsoni) in Tibet; and home range of the Brandt vole (Microtus brandti) in Mongolia. The home ranges of sheep and goats in nomadic Mongolian family are simple, elongated in shape and possess almost no track intersections. The daily routes possess the same pattern, but pass in different places and do not overlay the previous. Those of sheep and goats in settled nomad families in Inner Mongolia differ in shape, have multiple overlays and tend to cross previous paths. Grazing inside fenced pasture causes this pattern; grazing velocity and total distances are higher than that of Mongolian livestock. In Mongolia, surroundings of livestock watering sites are heavily degenerated in a range of 1 km radius. Pasture degradation attracts rodent species, Microtus brandti, to those sites. Analysis of the habitat selection by this rodent on Maximum Entropy Model showed that habitat most preferred by voles are degraded grasslands along roads, ger (tent-type movable house) and watering sites with percent contribution varying from 5.5 to 47.9, and permutation importance of 25.1; 48.7 and 20.9, respectively. We suggest that in conditions of arid and sub-arid land, the livestock and wild animal’s concentration around water sources may cause progressing degradation of pasture and desertification