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Rights: The University of Waikato
Published 18 June 2008 Referencing Hub media

ESR scientist Dr Wendy Williamson describes the process of developing an assay to detect viruses in the environment. She highlights the importance of checks to make sure that the method is accurate and that it is able to work even with complex samples. Only then can the scientist be confident that it will work on the environmental river samples.


An assay is a tool we use that will detect what we are looking for, and it has to have the chemicals to make the reaction occur. It has to have the physical conditions around it, the temperaturePH, to allow the chemistry to work. And so we put a sample in at one end, we put all the chemicals in to allow whatever the reaction happening, to make it happen, and then we measure a result at the end of it. And then we have to make sure the assay works in theory, so we do all that on the computer, and then we have to check that it works with a pure real sample, and then we have to take that and make sure it doesn't work with anything else, so we don't get false positives. And then we have to make sure the assay can work in these really, really difficult contexts, and for us working for the river survey, our most complex sample that we test our methods on is faecal material, because that's got a lot of compounds in it that inhibit these PCR reactions, and it takes 18 months to develop the assays that we are currently using for our river survey.

Elaine Moriarty & Naveena Karki, ESR, Christchurch