Hepatitis D virus (HDV) super-
infection of Hepatitis B virus (HBV)-infected patients is the most aggressive form of viral
hepatitis. HDV
infection is not susceptible to direct anti-HBV drugs, and only suboptimal
antiviral responses are obtained with
interferon (IFN)-alpha-based
therapy. To get insights on HDV replication and interplay with HBV in physiologically relevant hepatocytes, differentiated HepaRG (dHepaRG) cells, previously infected or not with HBV, were infected with HDV, and
viral markers were extensively analyzed. Innate and IFN responses to HDV were monitored by measuring pro-inflammatory and
interferon-stimulated gene (ISG) expression. Both mono- and super-infected dHepaRG cells supported a strong HDV intracellular replication, which was accompanied by a strong secretion of infectious HDV virions only in the super-
infection setting and despite the low number of co-infected cells. Upon HDV super-
infection, HBV replication markers including
HBeAg, total HBV-
DNA and pregenomic
RNA were significantly decreased, confirming the interference of HDV on HBV. Yet, no decrease of circular covalently closed HBV
DNA (cccDNA) and
HBsAg levels was evidenced. At the peak of HDV-
RNA accumulation and onset of interference on HBV replication, a strong type-I IFN response was observed, with
interferon stimulated genes, RSAD2 (Viperin) and IFI78 (MxA) being highly induced. We established a cellular model to characterize in more detail the direct interference of HBV and HDV, and the indirect interplay between the two viruses via innate immune responses. This model will be instrumental to assess molecular and immunological mechanisms of this viral interference.