HCV Genotyping: A Requisite Tool

Chronic viral hepatitis and its associated complications of liver damage is a global public health concern. HCV, a single-stranded RNA virus with substantial genetic diversity, is one of the main causative agents. A high mutation rate observed in HCV results in the emergence of various genotypes, or genetic lineages, which are sufficiently similar to one another but classified into discrete groups.

The genetic difference between genotypes is significant, with their RNA sequences varying by 30–35%. However, subtypes, with genetic sequences differ by 20–25%, indicate a closer relationship. The specific genotype and subtype of the virus can influence how it behaves within the human body and has been a major factor in determining the most effective course of medical treatment.

Genotyping tests performed by analysing the unique genetic sequence of the virus present in a blood sample. One of the most common methods is reverse hybridization, which uses probes that bind to specific, known genetic sequences of different genotypes and subtypes. An alternative technique involves directly sequencing a portion of the virus's genome and then using phylogenetic analysis to ascertain how it relates to known genotypes.

These tests have very good accuracy and can significantly improve patient management when conducted prior to starting antiviral medication. Molecular characterisation of viruses has now shifted from the research bench to reference labs and clinics, this shift should be fully leveraged for improved, long-term public health.

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