Dataset Information

High-Load Reovirus Infections Do Not Imply Physiological Impairment in Salmon.

ABSTRACT: The recent ubiquitous detection of PRV among salmonids has sparked international concern about the cardiorespiratory performance of infected wild and farmed salmon. Piscine orthoreovirus (PRV) has been shown to create substantial viremia in salmon by targeting erythrocytes for principle replication. In some instances, infections develop into heart and skeletal muscle inflammation (HSMI) or other pathological conditions affecting the respiratory system. Critical to assessing the seriousness of PRV infections are controlled infection studies that measure physiological impairment to critical life support systems. Respiratory performance is such a system and here multiple indices were measured to test the hypothesis that a low-virulence strain of PRV from Pacific Canada compromises the cardiorespiratory capabilities of Atlantic salmon. Contrary to this hypothesis, the oxygen affinity and carrying capacity of erythrocytes were unaffected by PRV despite the presence of severe viremia, minor heart pathology and transient cellular activation of antiviral response pathways. Similarly, PRV-infected fish had neither sustained nor appreciable differences in respiratory capabilities compared with control fish. The lack of functional harm to salmon infected with PRV in this instance highlights that, in an era of unprecedented virus discovery, detection of viral infection does not necessarily imply bodily harm and that viral load is not always a suitable predictor of disease within a host organism.

SUBMITTER: Zhang Y

PROVIDER: S-EPMC6425399 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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High-Load Reovirus Infections Do Not Imply Physiological Impairment in Salmon.

Zhang Yangfan Y Polinski Mark P MP Morrison Phillip R PR Brauner Colin J CJ Farrell Anthony P AP Garver Kyle A KA

Frontiers in physiology 20190313

The recent ubiquitous detection of PRV among salmonids has sparked international concern about the cardiorespiratory performance of infected wild and farmed salmon. Piscine orthoreovirus (PRV) has been shown to create substantial viremia in salmon by targeting erythrocytes for principle replication. In some instances, infections develop into heart and skeletal muscle inflammation (HSMI) or other pathological conditions affecting the respiratory system. Critical to assessing the seriousness of PR ...[more]

PMID: 30930782

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Project description:Heart and Skeletal Muscle Inflammation (HSMI), recently associated with a novel Atlantic salmon reovirus (ASRV), is currently one of the most prevalent inflammatory diseases in commercial Atlantic salmon farms in Norway. Mortality varies from low to 20%, but morbidity can be very high, reducing growth performance and causing considerable financial impact. Clinical symptoms, including myocarditis, myocardial and red skeletal muscle necrosis, correlate with the intensity of the inflammatory response. In the present study, the effects of two functional feeds (FF1 and FF2) were compared to a standard commercial reference feed (ST) in Atlantic salmon subjected to an ASRV challenge. The functional feeds had reduced levels of total lipid and digestible energy, and different levels and proportions of long-chain polyunsaturated fatty acids (LC-PUFA). The objective was to determine whether these feeds could provide effective protection by decreasing the inflammatory response associated with HSMI. Histopathology, viral load, fatty acid composition and gene expression of heart tissue were assessed over a period of 16 weeks post-infection with ASRV. The viral load and histopathology scores in heart tissue in response to ASRV infection were reduced in fish fed both functional feeds, with FF1 showing the greatest effect. Microarray hierarchical cluster analysis showed that the functional feeds greatly affected expression of inflammation/immune related genes over the course of the ASRV infection. Viral load correlated with up-regulation of pro-inflammatory genes at the early-mid stages of infection in fish fed the ST diet. Expression of inflammatory genes 16-weeks after ASRV challenge reflected the difference in efficacy between the functional feeds, with fish fed FF1 showing lower expression. Thus, severity of the lesions in heart tissue correlated with the intensity of the innate immune response and was associated with tissue fatty acid compositions. The present study demonstrated that dietary modulation through clinical nutrition had major influences on the development and severity of the response to ASRV infection in salmon. Thus, HSMI was reduced in fish fed the functional feeds, particularly FF1. The modulation of gene expression between fish fed the different feeds provided further insight into the molecular mechanisms and progression of the inflammatory and immune responses to ASRV infection in salmon.

Project description:Background Prevention of hearing loss via addressing potentially modifiable risk factors may offer means of reducing the global burden of hearing loss. Prior studies reported associations between individual markers of inflammation and risk of hearing impairment. Allostatic load is an index of cumulative physiological stressors, including inflammation, to multiple biological systems. Our aims were to investigate associations between allostatic load and both audiometric and self-reported hearing impairment and examine whether associations are stronger over time due to prolonged high allostatic load. Methods Data were taken from the English Longitudinal Study of Ageing (ELSA), a nationally representative study of people aged 50+ living in England over 3 time points between 2008 and 2014. Allostatic load score was comprised of thirteen different measures available at baseline and 4 years post-baseline (high-density lipoprotein/total cholesterol, triglyceride, fibrinogen, haemoglobin A1c, C-reactive protein, insulin-like growth factor 1 (IGF-1), systolic and diastolic blood pressure, mean arterial pressure, resting pulse rate, peak expiratory flow, BMI and waist circumference), measured using clinical cut-off points for normal biomarker parameters. Hearing acuity was measured with a simple handheld tone-producing device at follow-up 7 years post-baseline, while self-reported hearing impairment was measured at time point. Results We included samples of 4373 and 4430 for the cross-sectional and longitudinal analysis, respectively. In the cross-sectional model high allostatic load was associated both self-reported (OR = 1.08, 95% CI 1.0,1.1; p < 0.01) and objective hearing loss (OR = 1.10, 95% CI 1.1,1.2; p < 0.001) adjusting for age and sex. Cross-sectional associations between allostatic load and hearing were not significant after further adjustment for covariates (qualification, physical activity and smoking). In longitudinal modelling, high allostatic load was associated with both audiometric (Z score OR = 1.11, 95% CI 1.1,1.2; p < 0.001) and self-reported hearing impairment (OR = 1.08, 95% CI 1.0,1.1; p < 0.001) adjusting for age and sex. Allostatic load was no longer associated with self-reported hearing loss but the association with audiometric hearing impairment (OR = 1.08, 95% CI 1.03,1.13; p < 0.001) remained following additional adjustment for baseline self-reported hearing, education, physical activity, and smoking. Conclusions Prolonged high allostatic load was associated with risk of hearing impairment. Reducing allostatic load via healthy lifestyle changes including non-smoking, healthy diet and exercise may offer an opportunity to reduce the risk of hearing impairment in later life. Highlights • Allostatic load captures cumulative physiological stress which has consequence for subsequent hearing function.• Prolonged high allostatic load was associated with risk of objectively measured hearing impairment.• This association is shown in nationally representative longitudinal ageing study.

Dataset Information

High-Load Reovirus Infections Do Not Imply Physiological Impairment in Salmon.

Publications

High-Load Reovirus Infections Do Not Imply Physiological Impairment in Salmon.

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