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.