Capability and Capacity: Nuffield Australia Scholarships
Diagnostic detection of aquatic pathogens using real-time next generation sequencing
Current diagnostic programs generally rely on highly -specific assays for pathogen detection. While these techniques are invaluable, they are one dimensional and do not provide detailed information critical to a disease investigation. These gaps include the inability to detect unknown pathogens and potential variants of know pathogens and provide no additional genomic or transcriptomic data. Moreover, samples must be shipped to trained personnel in a laboratory, further delaying the time to diagnosis. The MinION, on the other hand, can theoretically detect any pathogen and can potentially be deployed to the field. Moreover, the MinION can rapidly generate full-length genomes, allowing for epidemiological tracking of viral or bacterial strains in near real-time. Such rapid data, which cannot be obtained as quickly using existing methods, are vital if the intention is to intervene in an outbreak and reduce impacts on the productivity and profitability of aquaculture facilities. For example, a rapid, early diagnosis may allow mitigating actions to be taken on-farm, such as the diversion of intake water, movement restrictions of stock and the isolation of infected ponds.
These qualities make the MinION an attractive complimentary platform to fill several gaps in the data obtained during disease outbreak investigations, or routine diagnostics, and potentially for use in the field. However, results from the misuse or lack of understanding of the technology could also have adverse regulatory implications for aquaculture industries. For example, without appropriate guidelines, an inexperienced diagnostician may misinterpret a distant DNA match in a pathogen database as a significant result, this may create unwanted attention to industry and potential stock destruction or changes to disease status that are unjustified. Thus, it is critical that the MinION is evaluated at the Australian Animal Health Laboratory, and guidelines and procedures are developed for accurate diagnostic evaluations. The activities detailed in this application will establish the feasibility of using the MinION for diagnostic applications, and ensure that the data is reliably generated and interpreted appropriately.
Toolbox for the estimation of fish population abundance
Abundance estimates are used both directly and indirectly in stock assessment processes to support fishery management. Australia’s fisheries research agencies all estimate fish population abundance in some way. These include genetic and conventional tagging, acoustics (active and passive), trawl and egg surveys, as well as using proxies of abundance such as catch. Each of these methods have benefits, biases and caveats linked to the method and to the fish species being assessed. For example, differences between life history and habitat can make an abundance estimation method that has worked for one species unsuitable for another. As the application of each method of estimating abundance is potentially species/scenario specific, potential use by researchers and managers can be fraught.
In developing or proposing an abundance estimate for use in fisheries assessment, researchers must have a clear understanding of the assessment framework in order to make sure that an abundance estimate can be used. Claims such as “this time series can then be used in stock assessment” must be verified by funding agencies (particularly beyond FRDC) and defensible. Proliferation of abundance estimation methods without links to the assessment process will not yield an expected benefit beyond knowledge accumulation.
A project is needed to capture the range of methods of estimating abundance for management purposes, and specify the conditions of use, limitations and readiness level for operational use. A decision tree and methods ‘toolbox’ that describes the techniques, their relative strengths and weaknesses will help researchers and managers identify the best suited abundance estimate approach, and guide research effort to overcome known weaknesses.
The development of a ‘toolbox’ of techniques would be used to inform:
1. techniques available to estimate abundance
2. suitability of them to different conditions such as life history, and data availability
3. requirements of the technique such as methods used, prerequisite expertise, data and cost; and
4. circumstances under which the technique can be used.
This project would also identify potential new approaches and technologies that might complement or replace current ones.