Battling a killer in Asia's lakes and rivers

18 December 2018

In the waterways of China and South-East Asia there lurks a killer against which there is no defence. It targets the young and can decimate entire generations. OK, so it doesn’t directly affect humans, but for the giant fresh water prawns that are its victims and the people who rely on the prawns as a food staple, it is a very serious problem.

The killer is a virus called Macrobrachium rosenbergii nodavirus (MrNV), which causes a disease known as white tail disease that infects the larvae of the giant freshwater prawn. An outbreak can wipe out all of the larvae it infects. The prawn is widely cultivated in Asia, the Americas and (to a lesser degree) Africa and the Middle East, but so far the outbreaks have been limited to Asia. The prawns, which can grow up to 35 cm in length, are an increasingly valuable food resource whose production now exceeds 200,000 tonnes a year and that are less environmentally harmful to farm than their saltwater cousins. There currently exists no vaccine or treatment available to tackle outbreaks of the disease.

To rectify this, an international team of researchers have been using the powerful imaging capabilities available at the Electron Bio-Imaging Centre (eBIC) at Diamond Light Source, to produce high-resolution images of the virus. These images have allowed scientists to infer the positions of individual atoms and thus build up a detailed picture of the virus’ structure – which is essential in the development of vaccines and treatments. The results have revealed that the virus might belong to new and previously unidentified class of viruses.

The researchers used a technique called cryo-electron microscopy to take images of almost 50,000 individual viruses, which were then compiled to produce one composite image that relieved the structure of the virus at extremely high resolution.

Images like this are important because anti-viral drugs have to target the virus without harming the host – to do this, researchers need to identify features that are unique to the virus. Although it is not possible to vaccinate the prawns in the way that cattle are vaccinated, it is hoped that the research will help to pave the way for the development of drug that will help to combat the disease.

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Last updated: 25 February 2019


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