LNP-IL-21 induced HBV clearance in rcccDNA-based persistence mouse model
Considering the facts that cccDNA is a key factor for HBV persistence and mouse hepatocytes do not support cccDNA formation for unknown reasons [22, 23], we previously constructed a recombinant cccDNA (rcccDNA) persistence mouse model based on Cre recombinase/Loxp system, in which rcccDNA is produced from a precursor rccccDNA (prcccDNA) under the action of Cre [14]. rcccDNA is highly similar to wild type cccDNA in size except a small extraneous intron that is removed via selective splicing upon transcription [14].
C57BL/6 mice transgenic for Cre recombinase were injected with adenovirus carrying prcccDNA (Adv/prcccDNA) via tail vein, and mice positive for serum HBV antigens for up to 4 weeks were injected with LNP-21 or LNP. As seen in Figure 4A, C-D , serum HBsAg, HBeAg and HBV DNA were cleared in all LNP-IL-21-treated mice (n = 6) by 8 w.p.i., but persisted at considerably highly levels in LNP-treated group (n = 6). LNP-IL-21-induced HBV clearance was associated with HBsAb seroconversion, together with IL-21 and ALT transient elevations which reverted to base line levels by 8 w.p.i. (Figure 4B, E-F ). Serum biochemical indexes for safety analysis, including total bilirubin and creatine kinase, maintained largely normal between two groups (Figure S5 ). At 8 w.p.i., expectedly, no intrahepatic HBV replication intermediates, rcccDNA or capsids were detected in LNP-IL-21-injected mice (n = 6) that had achieved HBsAg clearance (Figure 5 ), indicating true HBV clearance.