An international group of researchers has developed, and conducted initial trials on a new Hepatitis C test, based on a novel diagnostic target, the Hep C virus RNA sequence called 3′-X-tail element. Thanks to its highly conserved sequence across the subtypes of Hepatitis C viruses, 3′-X-tail can potentially usher a new, cheaper test, capable of HCV viral load monitoring and infection screening.
Cordis News, European Union’s official research and innovation information service, reports:
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).
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.
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.
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.