Hepatitis D virus (HDV) is a defective and neglected pathogen whose replication depends on hepatitis B virus (HBV). Its genome, a circular single-stranded RNA of only 1680 nucleotides, has a highly unusual structure, described as pseudo-double-stranded, resembling that of plant viroids. HDV is associated with the most severe form of chronic viral hepatitis, characterized by rapid progression to cirrhosis and a markedly increased risk of hepatocellular carcinoma. In 2020, the estimated global prevalence of HDV among individuals with chronic hepatitis B was 12 million people, or approximately 4.5%, although many regions of the world remain under-investigated.

The high genetic variability of the virus poses significant challenges for diagnosis, particularly for molecular detection. Current screening methods rely on serological detection of anti-HDV antibodies, followed, if positive, by confirmation through RT-qPCR detection of HDV RNA. However, the sensitivity and specificity of these tests vary between genotypes, and diagnostic standardization remains limited despite the introduction of an international HDV-RNA WHO gold standard. The development of pan-genotypic assays remains a major challenge, as does the harmonization of RNA extraction and quantification protocols.

In the era of new therapeutic options, such as bulevirtide, diagnostic capacities remain limited, especially in high-prevalence regions. In response, the WHO has recently issued recommendations to incorporate HDV testing into national viral hepatitis elimination strategies, emphasizing the importance of reflex testing and the need to strengthen molecular diagnostic capabilities, particularly for HDV RNA detection. Improving diagnosis will depend on the development of sensitive, standardized, and widely accessible tests that can detect all HDV genotypes, an essential step toward broader screening, better patient care, and a reduction in the morbidity and mortality associated with this infection.

During this webinar, Frédéric LE GAL, PhD (HDR), specialist in Hepatitis Delta Virus at the National Reference Center for HDV in France, will present all these diagnostic difficulties in relation to the characteristics of the virus with a view to improving tests for wide dissemination of screening and shedding light on the global epidemiology of this virus.

*We do not provide CECs for this webinar.