FIG. 4.
Relative infectivity of HDV particles bearing increasing ratio of Δ11-15 infectivity-deficient/wt pre-S1. Production of SL-HDV particles was achieved by transfection of 106 Huh-7 cells with 1 μg of pSVLD3 plasmid for production of HDV RNP, 1 μg of p123 for expression of wt S-HBsAg, together with 1 μg of a mixture of Δ115-153 L-HBsAg (as a surrogate for wt L-HBsAg) and Δ11-15 L-HBsAg expression vectors. The ratios of Δ11-15 to Δ115-153 plasmids used for transfection were 0/100, 10/90, 20/80, 30/70, 40/60, 50/50, 60/40, 70/30, 80/20, 90/10, and 100/0. (A) Particles from 0.5 ml of supernatant from transfected cells were analyzed for S- and L-HBsAg proteins by immunoblotting. Quantification of Δ11-15 and Δ115-153 proteins signals is indicated as percentages of total L-HBsAg. (B) After normalization of the different preparations of HDV particles for their viral RNA content, infectivity was evaluated in cultures of HepaRG cells by measuring the accumulation of HDV RNA in cells harvested at day 7 postinoculation. Quantification of intracellular HDV RNA signals by phosphorimager is indicated as percentages of the value for wt SL-HDV. Specific infectivity (y axis) is indicated as a function of the Δ11-15/total L-HBsAg ratio in the viral envelope (x axis).