Allicin inhibits HBV replication through the HBV promoter SP2

Objective To investigate the effect of allicin on the replication of hepatitis B virus (HBV) and to preliminarily elucidate its underlying molecular mechanisms. Methods HepG 2.2.15 cells were treated with different concentrations of allicin and the levels of HBsAg and HBeAg were assessed by ELISA. Cell viability was evaluated using the CCK-8 assay to determine the optimal concentration of allicin; HepG2-NTCP cells were incubated with the optimal concentration of allicin for 48 hours, and the expression of HBV-related markers was detected by RT-qPCR; The activity of four HBV promoters (Enh Ⅰ/Xp, SP1, SP2, and CP) was analyzed using a dual-luciferase reporter gene experiment. The effect of allicin on promoter activity was assessed; Gene-regulation tools were used to predict potential transcription factor that might bind to the promoter. After over-expressing the transcription factor, cells were incubated with allicin and the effect on promoter activity was examined; Finally, ChIP was used to confirm whether these transcription factors bind to the HBV promoters and whether allicin treatment affects this binding. Results Allicin significantly reduced the expression of HBsAg and slightly lowered the expression of HBeAg(P＜0.001); A concentration of 40 μmol/L allicin significantly inhibited HBV DNA replication and transcription(P＜0.05), without affecting cell viability; Allicin also significantly suppressed the activity of the HBV promoter SP2(P＜0.001). Further investigation revealed that the transcription factor SP1 could bind to the DNA sequence of the HBV promoter SP2, and this binding was significantly inhibited after allicin treatment(P＜0.001). Conclusions Allicin inhibits the binding of the transcription factor SP1 to HBV promoter SP2, thereby reducing the transcriptional activity of HBV and suppressing viral replication.