Hepatitis C genotype and drug resistance testing

Consultant/s: Imperial College Molecular Diagnostic Unit (unit manager: Steve Kaye)

Expertise: Virus genotyping, drug resistance testing

The Challenge

Therapy with direct-acting antiviral (DAA) drugs, a new type of Hepatitis C virus (HCV) treatment that targets the viral life cycle to inhibit viral production, is being rolled out globally. However, the efficacy of the treatment depends on the virus subtype, therefore it is important to determine the HCV genotype in advance of DAA therapy to ensure the patient will actually respond to this very costly treatment.

Additionally, sequence changes in the viral genome are associated with decreased susceptibility of the Hepatitis C Virus to DAAs. Detection of these mutations in the viral genome can be used to predict the susceptibility of the virus to currently licensed DAAs and thus can be used to optimise the use of DAA treatment on an individual patient basis.

The Solution

Genotyping and resistance testing are complex laboratory methods and are carried out in specialist units. The Molecular Diagnostics Unit (MDU) is developing new methods to address the challenges of HCV genotyping and resistance testing including…

• Sequencing from dried blood spots. The major advantages over liquid blood samples are the smaller quantity required and easier and safer shipping.
• Sequencing by next generation sequencing (NGS). Conventional gene sequencing (Sanger sequencing) is limited in its ability to detect drug resistance variants in a background of drug sensitive virus. NGS is much more sensitive, detecting down to 1% minority resistant variants.

In addition to testing for genotype and resistance, the team also offers bespoke training and advice in setting up similar testing facilities worldwide.

The Impact

• Savings for healthcare systems
• Public health benefits for countries with high prevalence of Hepatitis C – and their neighbours.

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