EU-funded researchers develop novel, economical blood test for hepatitis C
An international team of scientists has developed a new, accurate and affordable blood test for hepatitis C that represents a major breakthrough in controlling the spread of this dangerous virus. The procedure is described in the journal PLoS Medicine, and is in part an outcom...
An international team of scientists has developed a new, accurate and affordable blood test for hepatitis C that represents a major breakthrough in controlling the spread of this dangerous virus. The procedure is described in the journal PLoS Medicine, and is in part an outcome of the RiViGene ('Genomic inventory, forensic markers, and assessment of potential therapeutic and vaccine targets for viruses relevant in biological crime and terrorism') project, which was funded under the 'Policy support' Thematic area of the EU's Sixth Framework Programme (FP6).
Approximately 170 million people worldwide are infected with the hepatitis C virus (HCV), which causes liver cirrhosis (scarring) and liver cancer. The virus is usually spread through contact with the blood of an infected person, for instance by transfusion using unscreened blood or the use of inadequately sterilised medical instruments. Between 3 and 4 million people are newly infected every year. Treatments are not only costly but are also often ineffective.
In wealthy countries, donated blood is routinely screened for HCV using a commercially patented test called an RT-PCR assay. This test detects small amounts of HCV's RNA (ribonucleic acid), which allows the virus to replicate itself, and looks for a part of the viral genome called 5'-NCR.
In poorer countries, the use of this test is well beyond the means of most laboratories. A test might cost over USD 100 (EUR 77), of which USD 10 go to licensing fees alone. Also, the effectiveness of the test varies according to the strain (or genotype) of the virus, which differs amongst geographic regions.
To limit the spread of HCV, routine screening of blood used for transfusions in developing countries is essential; for this to be feasible, the test must be both effective and affordable. In the current study, the researchers looked for a new way to identify different strains of the virus using approximately 600 blood samples from the UK, Germany, Brazil, Singapore and South Africa.
Screening for all major strains of the virus is important for everyone, according to the researchers. 'In Asia, for example, we often find different hepatitis C viruses from ours,' said Dr Jan Felix Drexler of Bonn University. 'But when a tourist becomes infected in Thailand and subsequently donates blood in Germany, we must be able to diagnose these blood samples without fail, too.'
The researchers found that a test for a different part of the HCV genome, the '3'-X-tail element', accurately identified low concentrations of the viral RNA in a wide range of samples, and was also able to determine the quantity of viral RNA in these samples. This means that their test is just as effective, or perhaps more so, than the commercial assays currently in use.
'We are, at least, just as sensitive as the two best standard procedures,' commented Professor Christian Drosten of Bonn University, adding that 'This is true for all types of virus.' And, as Dr Drexler noted, 'This would be a significant breakthrough for containing the disease. After all, transfusions are a major source of propagation.'
The protocol used in the X-tail assay is robust, stable, effective and freely available; as such, it has the potential to improve blood safety in developing countries by providing a cheap and effective alternative to proprietary HCV assays. Indeed, the new test has already been used successfully to measure viral load in blood samples from 127 patients in a Brazilian laboratory at a fraction of the usual cost. Such measurement is important for monitoring therapeutic success and reducing the costs of treatment.
'For anyone wishing to use this test, we can also supply the control reagents,' said Dr Drexler. In contrast, commercial suppliers do not share the precise nature of their assays.
The RiviGene project, which ended in 2008, studied the genome sequences of security-relevant viruses, and sought to develop simple and robust identification methods for all viral genetic signatures. The genomic information collated by the consortium is used to investigate functional aspects of virus biology.