In vitro replication of hepatitis D virus using a new construct containing a cDNA dimer of HDV genome.

BACKGROUND There is no cell line susceptible to hepatitis D virus (HDV) infection and capable of stable replication of its genome. Different genetic-based approaches have been introduced to initiate HDV replication events so far. METHODS In order to construct a replicative model for HDV made from a unique genome sequence, two monomeric units of HDV full-length cDNA were joined together through a four-step cloning scheme. The resulting vector (pcDNA3.1-D2) containing two tandem repeats of HDV cDNA under CMV promoter control was then used in transfection experiments into COS7 and HuH7 cell lines. RESULTS HDV replication markers including expression of hepatitis delta antigen (HDAg), the only HDV-specific antigen, and synthesis of antigenomic RNA were shown in both transfected cell lines, indicating initiation of HDV genome replication. CONCLUSIONS Our results suggested that pcDNA3.1-D2, a vector containing a cDNA dimer of the HDV genome, originated from a unique full-length HDV molecule that is capable of replicating in cultured cells. This vector can be used conveniently for transfection experiments to study HDV molecular biology.