Viral infections of HDV and HBV were conducted in 48-well plates at multiplicities of genome equivalents of 500 and 100, respectively. Normally, 5 × 10 7 copies of genome equivalent HDV or 1 × 10 7 copies of genome equivalent HBV were inoculated in the presence or absence of entry inhibitors with 1 × 10 5 cells and incubated for 16 hr except otherwise indicated. Cells were then washed with medium for three times and maintained in PMM medium with medium change every 2-3 days. For HDV infection, 4% PEG 8000 was present during the 16 hours viral inoculation period similarly as described by Barrera et al. (2004) . Viral infection at different time points was analyzed by measuring viral DNA/ RNAs and viral antigen expression. Quantitative real time RT-PCR was used to quantify HDV total RNAs, strand-specific real time RT-PCR to determine copies of HDV genome and antigenome RNA (see below). For HBV viral infection on HepaRG cells and PHH, ∼ 4% PEG 8000 was present during the inoculation period as previously described by Gripon et al. (Gripon et al., 1993; Gripon et al., 2002; Schulze et al., 2007) . Viral infection of PTH was conducted in the absence of PEG8000. Culture medium was changed every 2-3 days. Secreted HBsAg and/or HBeAg were determined with commercial ELISA kits. Real-time PCR, with or without a prior reverse transcription step, was used for quantification of HBV-specific 3.5 kb pre-C and pregenomic RNA, total HBV sub-genomic RNA, and HBV cccDNA copies.