The contribution of molecular epidemiology to the understanding and control of viral diseases of salmonid aquaculture

Veterinary Research, Apr 2011

Molecular epidemiology is a science which utilizes molecular biology to define the distribution of disease in a population (descriptive epidemiology) and relies heavily on integration of traditional (or analytical) epidemiological approaches to identify the etiological determinants of this distribution. The study of viral pathogens of aquaculture has provided many exciting opportunities to apply such tools. This review considers the extent to which molecular epidemiological studies have contributed to better understanding and control of disease in aquaculture, drawing on examples of viral diseases of salmonid fish of commercial significance including viral haemorrhagic septicaemia virus (VHSV), salmonid alphavirus (SAV) and infectious salmon anaemia virus (ISAV). Significant outcomes of molecular epidemiological studies include: Improved taxonomic classification of viruses A better understanding of the natural distribution of viruses An improved understanding of the origins of viral pathogens in aquaculture An improved understanding of the risks of translocation of pathogens outwith their natural host range An increased ability to trace the source of new disease outbreaks Development of a basis for ensuring development of appropriate diagnostic tools An ability to classify isolates and thus target future research aimed at better understanding biological function While molecular epidemiological studies have no doubt already made a significant contribution in these areas, the advent of new technologies such as pyrosequencing heralds a quantum leap in the ability to generate descriptive molecular sequence data. The ability of molecular epidemiology to fulfil its potential to translate complex disease pathways into relevant fish health policy is thus unlikely to be limited by the generation of descriptive molecular markers. More likely, full realisation of the potential to better explain viral transmission pathways will be dependent on the ability to assimilate and analyse knowledge from a range of more traditional information sources. The development of methods to systematically record and share such epidemiologically important information thus represents a major challenge for fish health professionals in making the best future use of molecular data in supporting fish health policy and disease control.

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The contribution of molecular epidemiology to the understanding and control of viral diseases of salmonid aquaculture

Veterinary Research The contribution of molecular epidemiology to the understanding and control of viral diseases of salmonid aquaculture Michael Snow 0 0 Marine Scotland Science , 375 Victoria Road, Aberdeen, AB11 9DB Scotland , UK Molecular epidemiology is a science which utilizes molecular biology to define the distribution of disease in a population (descriptive epidemiology) and relies heavily on integration of traditional (or analytical) epidemiological approaches to identify the etiological determinants of this distribution. The study of viral pathogens of aquaculture has provided many exciting opportunities to apply such tools. This review considers the extent to which molecular epidemiological studies have contributed to better understanding and control of disease in aquaculture, drawing on examples of viral diseases of salmonid fish of commercial significance including viral haemorrhagic septicaemia virus (VHSV), salmonid alphavirus (SAV) and infectious salmon anaemia virus (ISAV). Significant outcomes of molecular epidemiological studies include: Improved taxonomic classification of viruses A better understanding of the natural distribution of viruses An improved understanding of the origins of viral pathogens in aquaculture An improved understanding of the risks of translocation of pathogens outwith their natural host range An increased ability to trace the source of new disease outbreaks Development of a basis for ensuring development of appropriate diagnostic tools An ability to classify isolates and thus target future research aimed at better understanding biological function While molecular epidemiological studies have no doubt already made a significant contribution in these areas, the advent of new technologies such as pyrosequencing heralds a quantum leap in the ability to generate descriptive molecular sequence data. The ability of molecular epidemiology to fulfil its potential to translate complex disease pathways into relevant fish health policy is thus unlikely to be limited by the generation of descriptive molecular markers. More likely, full realisation of the potential to better explain viral transmission pathways will be dependent on the ability to assimilate and analyse knowledge from a range of more traditional information sources. The development of methods to systematically record and share such epidemiologically important information thus represents a major challenge for fish health professionals in making the best future use of molecular data in supporting fish health policy and disease control. 1. Introduction 1.1 What is molecular epidemiology? 1.2 Setting the scene: fish viruses, aquaculture and molecular epidemiology 2. Case studies highlighting the contribution of molecular epidemiology to the understanding and control of viral disease of salmonid aquaculture 2.1 Viral haemorrhagic septicaemia virus 2.1.1 Overview 2.1.2 Molecular epidemiology facilitates the taxonomic classification of VHSV and provides a basis for understanding the relationship between isolates 2.1.3 Understanding genetic relationships provides an insight into the origins of VHS in aquaculture 2.1.4 Understanding the range of naturally occurring pathogens highlights the risk associated with their translocation 2.1.5 Identification of genetic relationships is used to trace the spread of pathogens in aquaculture 2.1.6 A sound knowledge of molecular epidemiology supports strategies for surveillance and further knowledge 2.2 Salmonid alphavirus (SAV) 2.2.1 Overview 2.2.2 Molecular epidemiology facilitates the taxo nomic classification of SAV and provides a basis for understanding the relationship between isolates 2.2.3 Understanding genetic relationships provides an insight into the origins of SAV in aquaculture 2.2.4 Identification of genetic relationships is used to trace the spread of pathogens in aquaculture 2.2.5 A sound knowledge of molecular epidemiology supports strategies for surveillance and further knowledge 2.3 Infectious salmon anaemia virus (ISAV) 2.3.1 Overview 2.3.2 Molecular epidemiology facilitates the taxonomic classification of ISAV and provides a basis for understanding the relationship between isolates 2.3.3 Understanding genetic relationships provides an insight into the origins of ISAV in aquaculture 2.3.4 Identification of genetic relationships is used to trace the spread of pathogens in aquaculture 2.3.5 A sound knowledge of molecular epidemiology supports strategies for surveillance and further knowledge 3. Future perspectives and challenges 4. Competing interests 1. Introduction 1.1 What is molecular epidemiology? Epidemiology, or the study of factors affecting the health of populations is as old as science itself, with Hippocrates (460-377 BC) being the first to examine the relationship between disease occurrence and environmental issues. More recent technological developments have facilitated the identification and exploitation of molecular biom (...truncated)


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Michael Snow. The contribution of molecular epidemiology to the understanding and control of viral diseases of salmonid aquaculture, Veterinary Research, 2011, pp. 56, 42, DOI: 10.1186/1297-9716-42-56