The isolation of infectious salmon anaemia virus (ISAV) from asymptomatic wild fish species including wild salmon, sea trout and eel established that wild fish can be a reservoir of ISAV for farmed Atlantic salmon. This report characterizes the biological properties of ISAV isolated from a disease outbreak in farmed Coho salmon in Chile and compares it with ISAV isolated from farmed Atlantic salmon in Canada and Europe. The virus that was isolated from Coho salmon tissues was initially detected with ISAV-specific RT-PCR (reverse transcription-polymerase chain reaction). The ability of the virus to grow in cell culture was poor, as cytopathology was not always conspicuous and isolation required passage in the presence of trypsin. Virus replication in cell culture was detected by RT-PCR and IFAT (indirect fluorescent antibody test), and the virus morphology was confirmed by positive staining electron microscopy. Further analysis of the Chilean virus revealed similarities to Canadian ISAV isolates in their ability to grow in the CHSE-214 cell line and in viral protein profile. Sequence analysis of genome segment 2, which encodes the viral RNA polymerase PB1, and segment 8, which encodes the nonstructural proteins NS1 and NS2, showed the Chilean virus to be very similar to Canadian strains of ISAV. This high sequence similarity of ISAV strains of geographically distinct origins illustrates the highly conserved nature of ISAV proteins PB1, NS1 and NS2 of ISAV. It is noteworthy that ISAV was associated with disease outbreaks in farmed Coho salmon in Chile without corresponding clinical disease in farmed Atlantic salmon. This outbreak, which produced high mortality in Coho salmon due to ISAV, is unique and may represent the introduction of the virus to a native wild fish population or a new strain of ISAV. KEY WORDS: ISAV in Coho salmon · ISAV morphology · Immunoprecipitation of ISAV proteins Resale or republication not permitted without written consent of the publisherDis Aquat Org 45: [9][10][11][12][13][14][15][16][17][18] 2001 associated, resulting in focalized infection of the cell monolayer and slow development of CPE. ISAV isolates from Norway and Scotland, similar to the second Canadian group (the CHSE-negative phenotype), do not produce CPE in the CHSE-214 cell line. However, there are significant nucleotide and amino acid sequence differences between the European and Canadian isolates on RNA segments 2 and 8 (Blake et al. 1999), and the European isolates could be differentiated from Canadian isolates by reverse transcriptionpolymerase chain reaction (RT-PCR) and restriction fragment length polymorphism (RFLP) on RNA segment 2 (Kibenge et al. 2000).The present study characterizes an orthomyxo-like virus isolated from farmed Coho salmon Oncorhynchus kisutch in Chile, with clinical disease. While erythrocytic inclusion body syndrome virus (EIBSV) was detected in one fish sample, the orthomyxo-like virus was found in several fish tissue pools from the affected farms. The virus was biologically chara...

Background: Infectious salmon anaemia (ISA) virus (ISAV), which causes ISA in marine-farmed Atlantic salmon, is an orthomyxovirus belonging to the genus Isavirus, family Orthomyxoviridae. ISAV agglutinates erythrocytes of several fish species and it is generally accepted that the ISAV receptor destroying enzyme dissolves this haemagglutination except for Atlantic salmon erythrocytes. Recent work indicates that ISAV isolates that are able to elute from Atlantic salmon erythrocytes cause low mortality in challenge experiments using Atlantic salmon. Previous work on ISAVinduced haemagglutination using the highly pathogenic ISAV strain NBISA01 and the low pathogenic ISAV strain RPC/NB-04-0851, showed endocytosis of NBISA01 but not RPC/NB-04-0851. Realtime RT-PCR was used to assess the viral RNA levels in the ISAV-induced haemagglutination reaction samples, and we observed a slight increase in viral RNA transcripts by 36 hours in the haemagglutination reaction with NBISA01 virus when the experiment was terminated. However, a longer sampling interval was considered necessary to confirm ISAV replication in fish erythrocytes and to determine if the infected cells mounted any innate immune response. This study examined the possible ISAV replication and Type I interferon (IFN) system gene induction in Atlantic salmon erythrocytes following ISAV haemagglutination.

Background: The DNA-binding transcription factor Wilms' Tumor Suppressor-1 (WT1) plays an essential role in nephron progenitor differentiation during renal development. We previously used Wt1 chromatinimmunoprecipitation coupled to microarray (ChIP-chip) to identify novel Wt1 target genes that may regulate nephrogenesis in vivo. We discovered that all three members of the SoxC subfamily, namely, Sox4, Sox11, and Sox12, are bound by Wt1 in mouse embryonic kidneys in vivo. SoxC genes play master roles in determining neuronal and mesenchymal progenitor cell fate in a multitude of developmental processes, but their function in the developing kidney is largely unknown. Results: Here we show that all three SoxC genes are expressed in the nephrogenic lineages during renal development. Conditional ablation of Sox4 in nephron progenitors and their cellular descendants (Sox4 nephron-mice) results in a significant reduction in nephron endowment. By postnatal day (P)7, Sox4 nephron-renal corpuscles exhibit reduced numbers of Wt11 podocytes together with loss of expression of the slit diaphragm protein nephrin. SoxC genes exhibit overlapping but distinct patterns of expression in the nephrogenic lineages during renal development. Conditional ablation of Sox4 in the nephrogenic lineage results in reduced nephron number. Postnatal Sox4 nephron-mice develop severe early-onset kidney injury leading to renal failure in vivo.

Apoptosis may play a role in the pathogenesis of feline corneal sequestration independent of the presence of DNA of these infectious organisms. Prospective clinical studies are warranted to further understand the significance of T. gondii in relation to feline corneal sequestration.

No abstract