A chance discovery has opened up a new method to find unknown viruses.(Photo: Oxford University)
Unknown virus detected through salmon DNA studies
Friday, August 11, 2017, 23:50 (GMT + 9)
A team of scientists from Oxford University’s Department of Zoology found traces of a new group of viruses, related to herpesviruses, scattered in fragments of 15 different species of fish, including the Atlantic salmon and rainbow trout.
The researchers developed algorithms that detect DNA from viruses that happen to be in the blood or tissue sample of the species studied. The research focused on fish genomes as an example, but the method could be used to identify viruses in a range of different species.
As part of their research, the group found that next-generation sequencing and its associated online DNA databases could be used in the field of viral discovery.
Next-generation sequencing allows scientists to gather vast amounts of data, from a single piece of DNA, which is then collated into huge, online, genome databases that are publically accessible.
Dr Aris Katzourakis, an Associate Professor, and Dr Amr Aswad, Research Associate at Oxford’s Department of Zoology, initially discovered the new use for the database, by chance. While looking for an ancient herpes virus in primates, they found evidence of two new undocumented viruses.
Spurred by their accidental discovery, the scientists set out to see if they could intentionally achieve the same result. So, in a separate project to find new fish-infecting herpes viruses, they used the technique to examine more than 50 fish genomes for recognisable viral DNA.
To confirm that the viral evidence was not simply a fluke, or a data processing error, they tested additional samples from a local supermarket and sushi restaurant. The same viral fragments were found in the bought samples.
The key to the success of this research is in its inter-disciplinary approach, combining techniques from two fields: evolutionary biology and genomics. Together, these are at the core of the new field of paleovirology – the study of ancient viruses that have integrated their DNA into that of their hosts, sometimes millions of years ago. Each technique used has been developed to analyse huge quantities of DNA sequence data.
“One of the real strengths of this technique, as compared to more traditional virology approaches, is the speed of discovery, and the lack of reliance on identifying a diseased individual. The viral data collected, that may otherwise be discarded as a nuisance, is a unique resource for looking for both pathogenic and benign viruses that would otherwise have remained undiscovered,” Dr Katzourakis stressed.
The team will next begin to identify the impact of the viruses and whether they have any long term implications for disease, or commercial fish-farming.
The study results were published in the scientific journal Virus Evolution.