A user-friendly approach for detecting the hepatitis C virus has been developed by scientists in China. 

Hepatitis C is a blood-borne disease that affects the liver and accounts for almost half of the 4000 liver transplantations done each year. Monitoring the hepatitis C virus (HCV) in the body can be used to diagnose and confirm active infections and can also be used to assess a patient's response to therapy. Now, Hui Zhang, Chenxin Cai and co-workers at Nanjing Normal University have developed an electrochemical way to detect and quantify HCV. 

The hepatitis C virus causes around 10000 deaths each year in the US alone © Centres for Disease Control and Prevention

The approach uses a gold electrode coated with a DNA probe labelled with the dye thionine. Samples containing virus are pre-treated with a transcriptase enzyme to produce complementary DNA (cDNA), a synthetic oligonucleotide related to the HCV.  When the electrode is placed in the sample, the DNA probe binds to the cDNA to form a DNA double helix. If this is then treated with an endonuclease enzyme, the helix is cleaved, removing the thionine label. The detection works by monitoring the loss of thionine's voltammetric signal after the enzyme treatment: the smaller the signal, the more cDNA in the tested sample. Using this technique, Cai's team was able to detect HCV in real patient samples.

Cai explains that there are other methods for detecting HCV but these are considered to be 'time-consuming and laborious, and require sophisticated and expensive instruments. This electrochemical approach not only allows for ease of performance and good specificity but can also be used as a general method of DNA detection,' he says. 

Bernie Kraatz, an expert in biosensors and detection at the University of Western Ontario, London, Canada, says that 'the system appears surprisingly robust to potential contaminants such as proteins that tend to pollute gold surfaces and is able to work under real-to-life conditions. This alone is noteworthy and interesting and demonstrates the potential usefulness of this approach.'

The researchers say that they hope their technique can be further developed and be used for clinical diagnosis.

Paul Cooper 

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