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Research Objective - Mortality in European Oysters

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Viral DNA detection- the key to healthy oysters

In the past decade, mortality rates in European oyster hatcheries have soared, and the most likely culprit is believed to be a herpes-like virus. In response to this problem, a consortium of industry and research professionals applied Polymerase chain reaction (PCR) methods in order to detect viral DNA in oysters within 24 hours, and consequently decrease mortality rates and increase the profitability of European hatcheries.

Health

Since 1991, the increase in oyster mortality rates in European hatcheries has caused significant deficits in the industry. Although measures have previously been adopted to detect some infections, other uncontrolled variables continue to ravage the industry, especially during the last ten years. One of the most devastating of these variables is a group of herpes-like viruses, which act as causative agents of larval mortalities in various European countries. This consortium of French, British, Spanish and Irish professionals utilised Polymerase chain reaction (PCR) techniques to discover the DNA of herpes-like viruses in larval samples of diverse species and of different European origins. Polymerase chain reaction (PCR) constitutes a very reliable, accurate, and sensitive way of finding viruses in specimens. PCR magnifies the quantity of copies of a precise DNA area. This results in an adequate amount of DNA for proper testing and consequent DNA identification. Within the scope of this methodology, the consortium established that some PCR primer pairs are more suitable than others for herpes-like virus DNA detection in oysters. Specifically, the primer pair C2/C6 proved to be the optimal choice as it exhibits characteristics such as great sensitivity, and simple Polymerase chain reactions that translate into processing ease. Also, by using this pair, the researchers found that they could limit reagent use and decrease contamination. It is crucial to note that this PCR protocol is more effective than the nested PCR protocol using A4/A5 and A5/A6 primer pairs. In fact, the C2/C6 primer pair allowed herpes-like viral DNA identification in under 24 hours. Further results of this consortium's research include a 21% positive viral DNA identification in French, Spanish and British hatcheries. This finding verified that herpes-like viruses are responsible for oyster mortality problems in European hatcheries. By making available a reliable, accurate, and sensitive Polymerase chain reaction method for the identification of such viruses plaguing the hatchery industry, this consortium created a useful tool for the improved management of larval rearing. Also, the fact that results are obtained within 24 hours means that if some hatcheries are experiencing larval mortalities in specific groups of larvae, further contamination of other oyster batches by the herpes-like virus could be avoided. Another advantage of this consortium's innovation is that this PCR technique also allows scientists to research the biology of the virus. In effect, this particular PCR method provides the oyster hatchery industry with effective weapons for fighting viral contamination and profit losses.

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