Dataset Information

Infectious salmon anaemia virus (ISAV) isolated from the ISA disease outbreaks in Chile diverged from ISAV isolates from Norway around 1996 and was disseminated around 2005, based on surface glycoprotein gene sequences.

ABSTRACT: BACKGROUND: Infectious salmon anaemia (ISA) virus (ISAV) is a pathogen of marine-farmed Atlantic salmon (Salmo salar); a disease first diagnosed in Norway in 1984. For over 25 years ISAV has caused major disease outbreaks in the Northern hemisphere, and remains an emerging fish pathogen because of the asymptomatic infections in marine wild fish and the potential for emergence of new epidemic strains. ISAV belongs to the family Orthomyxoviridae, together with influenza viruses but is sufficiently different to be assigned to its own genus, Isavirus. The Isavirus genome consists of eight single-stranded RNA species, and the virions have two surface glycoproteins; fusion (F) protein encoded on segment 5 and haemagglutinin-esterase (HE) protein encoded on segment 6. However, comparison between different ISAV isolates is complicated because there is presently no universally accepted nomenclature system for designation of genetic relatedness between ISAV isolates. The first outbreak of ISA in marine-farmed Atlantic salmon in the Southern hemisphere occurred in Chile starting in June 2007. In order to describe the molecular characteristics of the virus so as to understand its origins, how ISAV isolates are maintained and spread, and their virulence characteristics, we conducted a study where the viral sequences were directly amplified, cloned and sequenced from tissue samples collected from several ISA-affected fish on the different fish farms with confirmed or suspected ISA outbreaks in Chile. This paper describes the genetic characterization of a large number of ISAV strains associated with extensive outbreaks in Chile starting in June 2007, and their phylogenetic relationships with selected European and North American isolates that are representative of the genetic diversity of ISAV. RESULTS: RT-PCR for ISAV F and HE glycoprotein genes was performed directly on tissue samples collected from ISA-affected fish on different farms among 14 fish companies in Chile during the ISA outbreaks that started in June 2007. The genes of the F and HE glycoproteins were cloned and sequenced for 51 and 78 new isolates, respectively. An extensive comparative analysis of ISAV F and HE sequence data, including reference isolates sampled from Norway, Faroe Islands, Scotland, USA, and Canada was performed. Based on phylogenetic analysis of concatenated ISAV F and HE genes of 103 individual isolates, the isolates from the ISA outbreaks in Chile grouped in their own cluster of 7 distinct strains within Genotype I (European genotype) of ISAV, with the closest relatedness to Norwegian ISAVs isolated in 1997. The phylogenetic software program, BACKTRACK, estimated the Chile isolates diverged from Norway isolates about 1996 and, therefore, had been present in Chile for some time before the recent outbreaks. Analysis of the deduced F protein sequence showed 43 of 51 Chile isolates with an 11-amino acid insert between 265N and 266Q, with 100% sequence identity with Genotype I ISAV RNA segment 2. Twenty four different HE-HPRs, including HPR0, were detected, with HPR7b making up 79.7%. This is considered a manifestation of ISAV quasispecies HE protein sequence diversity. CONCLUSION: Taken together, these findings suggest that the ISA outbreaks were caused by virus that was already present in Chile that mutated to new strains. This is the first comprehensive report tracing ISAV from Europe to South America.

SUBMITTER: Kibenge FS

PROVIDER: S-EPMC2710322 | biostudies-literature | 2009

REPOSITORIES: biostudies-literature

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Infectious salmon anaemia virus (ISAV) isolated from the ISA disease outbreaks in Chile diverged from ISAV isolates from Norway around 1996 and was disseminated around 2005, based on surface glycoprotein gene sequences.

Kibenge Frederick S B FS Godoy Marcos G MG Wang Yingwei Y Kibenge Molly J T MJ Gherardelli Valentina V Mansilla Soledad S Lisperger Angelica A Jarpa Miguel M Larroquete Geraldine G Avendaño Fernando F Lara Marcela M Gallardo Alicia A

Virology journal 20090626

<h4>Background</h4>Infectious salmon anaemia (ISA) virus (ISAV) is a pathogen of marine-farmed Atlantic salmon (Salmo salar); a disease first diagnosed in Norway in 1984. For over 25 years ISAV has caused major disease outbreaks in the Northern hemisphere, and remains an emerging fish pathogen because of the asymptomatic infections in marine wild fish and the potential for emergence of new epidemic strains. ISAV belongs to the family Orthomyxoviridae, together with influenza viruses but is suffi ...[more]

PMID: 19558648

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Project description:ABSTACT: Infectious salmon anaemia (ISA) is a serious disease of marine-farmed Atlantic salmon (Salmo salar) caused by ISA virus (ISAV), which belongs to the genus Isavirus, family Orthomyxoviridae. ISA is caused by virulent ISAV strains with deletions in a highly polymorphic region (HPR) of the hemagglutinin-esterase (HE) protein (designated virulent ISAV-HPR?). This study shows the historic dynamics of ISAV-HPR? and ISAV-HPR0 in Chile, the genetic relationship among ISAV-HPR0 reported worldwide and between ISAV-HPR0 and ISAV-HPR? in Chile, and reports the 2013 ISA outbreak in Chile. The first ISA outbreak in Chile occurred from mid-June 2007 to 2010 and involved the virulent ISAV-HPR7b, which was then replaced by a low pathogenic ISAV-HPR0 variant. We analyzed this variant in 66 laboratory-confirmed ISAV-HPR0 cases in Chile in comparison to virulent ISAV-HPR? that caused two new ISA outbreaks in April 2013. Multiple alignment and phylogenetic analysis of HE sequences from all ISAV-HPR0 viruses allowed us to identify three genomic clusters, which correlated with three residue patterns of ISAV-HPR0 (360PST362, 360PAN362 and 360PAT362) in HPR. The virus responsible for the 2013 ISAV-HPR? cases in Chile belonged to ISAV-HPR3 and ISAV-HPR14, and in phylogenetic analyses, both clustered with the ISAV-HPR0 found in Chile. The ISAV-HPR14 had the ISAV-HPR0 residue pattern 360PAT362, which is the only type of ISAV-HPR0 variant found in Chile. This suggested to us that the 2013 ISAV-HPR? re-emerged from ISAV-HPR0 that is enzootic in Chilean salmon aquaculture and were not new introductions of virulent ISAV-HPR? to Chile. The clinical presentations and diagnostic evidence of the 2013 ISA cases indicated a mixed infection of ISAV with the ectoparasite Caligus rogercresseyi and the bacterium Piscirickettsia salmonis, which underscores the need for active ISAV surveillance in areas where ISAV-HPR0 is enzootic, to ensure early detection and control of new ISA outbreaks, as it is considered a risk factor. This is the first report of ISA linked directly to the presence of ISAV-HPR0, and provides strong evidence supporting the contention that ISAV-HPR0 shows a strong relationship to virulent ISAV-HPR? viruses and the possibility that it could mutate to virulent ISAV-HPR?.

Project description:BackgroundInfectious salmon anaemia (ISA) virus (ISAV) belongs to the genus Isavirus, family Orthomyxoviridae. ISAV occurs in two basic genotypes, North American and European. The European genotype is more widespread and shows greater genetic variation and greater virulence variation than the North American genotype. To date, all of the ISAV isolates from the clinical disease, ISA, have had deletions in the highly polymorphic region (HPR) on ISAV segment 6 (ISAV-HPRΔ) relative to ISAV-HPR0, named numerically from ISAV-HPR1 to over ISAV-HPR30. ISA outbreaks have only been reported in farmed Atlantic salmon, although ISAV has been detected by RT-PCR in wild fish. It is recognized that asymptomatically ISAV-infected fish exist. There is no universally accepted ISAV RT-qPCR TaqMan® assay. Most diagnostic laboratories use the primer-probe set targeting a 104 bp-fragment on ISAV segment 8. Some laboratories and researchers have found a primer-probe set targeting ISAV segment 7 to be more sensitive. Other researchers have published different ISAV segment 8 primer-probe sets that are highly sensitive.MethodsIn this study, we tested 1,106 fish tissue samples collected from (i) market-bought farmed salmonids and (ii) wild salmon from throughout British Columbia (BC), Canada, for ISAV using real time RT-qPCR targeting segment 8 and/or conventional RT-PCR with segment 8 primers and segment 6 HPR primers, and by virus isolation attempts using Salmon head kidney (SHK-1 and ASK-2) cell line monolayers. The sequences from the conventional PCR products were compared by multiple alignment and phylogenetic analyses.ResultsSeventy-nine samples were "non-negative" with at least one of these tests in one or more replicates. The ISAV segment 6 HPR sequences from the PCR products matched ISAV variants, HPR5 on 29 samples, one sample had both HPR5 and HPR7b and one matched HPR0. All sequences were of European genotype. In addition, alignment of sequences of the conventional PCR product segment 8 showed they had a single nucleotide mutation in the region of the probe sequence and a 9-nucleotide overlap with the reverse primer sequence of the real time RT-qPCR assay. None of the classical ISAV segment 8 sequences in the GenBank have this mutation in the probe-binding site of the assay, suggesting the presence of a novel ISAV variant in BC. A phylogenetic tree of these sequences showed that some ISAV sequences diverted early from the classical European genotype sequences, while others have evolved separately. All virus isolation attempts on the samples were negative, and thus the samples were considered "negative" in terms of the threshold trigger set for Canadian federal regulatory action; i.e., successful virus isolation in cell culture.ConclusionsThis is the first published report of the detection of ISAV sequences in fish from British Columbia, Canada. The sequences detected, both of ISAV-HPRΔ and ISAV-HPR0 are of European genotype. These sequences are different from the classical ISAV segment 8 sequences, and this difference suggests the presence of a new ISAV variant of European genotype in BC. Our results further suggest that ISAV-HPRΔ strains can be present without clinical disease in farmed fish and without being detected by virus isolation using fish cell lines.

Project description:ContextDuring the past decade, the introduction of generic versions of newer antidepressants and the release of Food and Drug Administration warnings regarding suicidality in children, adolescents, and young adults may have had an effect on cost and quality of depression treatment.ObjectivesTo examine longitudinal trends in health service utilization, spending, and quality of care for depression.DesignObservational trend study.SettingFlorida Medicaid enrollees, between July 1, 1996, and June 30, 2006. Patients Annual cohorts aged 18 to 64 years diagnosed as having depression.Main outcome measuresMental health care spending (adjusted for inflation and case mix), as well as its components, including inpatient, outpatient, and medication expenditures. Quality-of-care measures included medication adherence, psychotherapy, and follow-up visits.ResultsMental health care spending increased from a mean of $2802 per enrollee to $3610 during this period (29% increase). This increase occurred despite a mean decrease in inpatient spending from $641 per enrollee to $373 and was driven primarily by an increase in pharmacotherapy spending (up 110%), the bulk of which was due to spending on antipsychotics (949% increase). The percentage of enrollees with depression who were hospitalized decreased from 9.1% to 5.1%, and the percentage who received psychotherapy decreased from 56.6% to 37.5%. Antidepressant use increased from 80.6% to 86.8%, anxiety medication use was unchanged at 62.7% and 64.4%, and antipsychotic use increased from 25.9% to 41.9%. Changes in quality of care were mixed, with antidepressant use improving slightly, psychotherapy utilization fluctuating, and follow-up visits decreasing.ConclusionsDuring a 10-year period, spending for Medicaid enrollees with depression increased substantially, with minimal improvements in quality of care. Antipsychotic use contributed significantly to the increase in spending, while contributing little to traditional measures of quality of care.

Dataset Information

Infectious salmon anaemia virus (ISAV) isolated from the ISA disease outbreaks in Chile diverged from ISAV isolates from Norway around 1996 and was disseminated around 2005, based on surface glycoprotein gene sequences.

Publications

Infectious salmon anaemia virus (ISAV) isolated from the ISA disease outbreaks in Chile diverged from ISAV isolates from Norway around 1996 and was disseminated around 2005, based on surface glycoprotein gene sequences.

Similar Datasets

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