Hepatitis B virus-3p-siRNA inhibits hepatitis B virus replication and activates interferon-βexpression in mice / 中华传染病杂志

Objective To observe the activation of anti-viral innate immune response of type Ⅰinterferon and inhibition of hepatitis B virus (HBV)genome replication in mice by HBV-3p-siRNA. Methods HBV-3p-siRNA was designed by targeting specific sequence of HBV S/P mRNA and was generated by in vitro transcription.Negative control siRNA (NC-siRNA)and non-modified HBV-siRNA were used as control groups.Blood samples were collected from tail vein of mice and the model of HBV-infected mice were established by hydrodynamic injection.Forty mice were divided into 4 groups with 10 in each group.The model group was only injected with pGL3.0-HBV1 .2 copy plasmid.The negative control group received peritoneal injection of NC-siRNA.HBV-siRNA group received peritoneal injection of HBV-siRNA and HBV-3p-siRNA group received peritoneal injection of HBV-3p-siRNA.The interferon-β(IFN-β)and hepatitis B surface antigen (HBsAg)in serum were detected by enzyme linked immunosorbent assay (ELISA).The copies of HBV DNA were assessed by fluore scence quantitative polymerase chain reaction (PCR ).The statistical difference between groups was determined using One way-ANOVA analysis by LSD or Dunnett T3.Results Serum level of IFN-β was (12.37±5 .32)pg/mL in model group,(22.61 ±6.29 )pg/mL in negative control group,(26.40±5 .39)pg/mL in HBV-siRNA group and (68.37± 21 .00 ) pg/mL in HBV-3p-siRNA group.The secretions of IFN-β into serum were significantly enhanced by HBV-siRNA and HBV-3p-siRNA compared with model group (F =23.988 and 46.523,respectively,both P <0.01).Serum level of HBsAg was (2 864.86±907.11 )ng/mL in model group,(2 198.86±456.89 )ng/mL in negative control group,(1 049.71 ± 396.28 )ng/mL in HBV-siRNA group and (640.86±383.08)ng/mL in HBV-3p-siRNA group.The expressions of HBsAg were inhibited by HBV-3p-siRNA and HBV-siRNA compared with model group (F = 23.537 and 39.144, respectively;P =0.025 and 0.010,respectively).Serum level of HBV DNA was (2.54 ×104 ±1 .46 × 104 )copy/mL in model group,(2.22×104 ±2.62×103 )copy/mL in negative control group,(3.59×103 ±2.88×103 )copy/mL in HBV-siRNA group and (2.65 ×103 ±1 .46×103 )copy/mL in HBV-3p-siRNA group.Serum level of HBV DNA were inhibited by HBV-3p-siRNA and HBV-siRNA compared with model group (F =15 .013 and 16.741 ,respectively,both P <0.05 ).All of the indicated siRNA used in the experiments showed no apparent effects on the body mass index of the mice models.Conclusion HBV-3p-siRNA,which induces the production of IFN-β and inhibits HBV replication through gene silencing in vivo ,may be a powerful bifunctional antiviral molecule.

Coronavirus membrane-associated papain-like proteases induce autophagy through interacting with Beclin1 to negatively regulate antiviral innate immunity

Autophagy plays important roles in modulating viral replication and antiviral immune response. Coronavirus infection is associated with the autophagic process, however, little is known about the mechanisms of autophagy induction and its contribution to coronavirus regulation of host innate responses. Here, we show that the membrane-associated papain-like protease PLP2 (PLP2-TM) of coronaviruses acts as a novel autophagy-inducing protein. Intriguingly, PLP2-TM induces incomplete autophagy process by increasing the accumulation of autophagosomes but blocking the fusion of autophagosomes with lysosomes. Furthermore, PLP2-TM interacts with the key autophagy regulators, LC3 and Beclin1, and promotes Beclin1 interaction with STING, the key regulator for antiviral IFN signaling. Finally, knockdown of Beclin1 partially reverses PLP2-TM's inhibitory effect on innate immunity which resulting in decreased coronavirus replication. These results suggested that coronavirus papain-like protease induces incomplete autophagy by interacting with Beclin1, which in turn modulates coronavirus replication and antiviral innate immunity.

SARS coronavirus papain-like protease inhibits the type I interferon signaling pathway through interaction with the STING-TRAF3-TBK1 complex

SARS coronavirus (SARS-CoV) develops an antagonistic mechanism by which to evade the antiviral activities of interferon (IFN). Previous studies suggested that SARS-CoV papain-like protease (PLpro) inhibits activation of the IRF3 pathway, which would normally elicit a robust IFN response, but the mechanism(s) used by SARS PLpro to inhibit activation of the IRF3 pathway is not fully known. In this study, we uncovered a novel mechanism that may explain how SARS PLpro efficiently inhibits activation of the IRF3 pathway. We found that expression of the membrane-anchored PLpro domain (PLpro-TM) from SARS-CoV inhibits STING/TBK1/IKKε-mediated activation of type I IFNs and disrupts the phosphorylation and dimerization of IRF3, which are activated by STING and TBK1. Meanwhile, we showed that PLpro-TM physically interacts with TRAF3, TBK1, IKKε, STING, and IRF3, the key components that assemble the STING-TRAF3-TBK1 complex for activation of IFN expression. However, the interaction between the components in STING-TRAF3-TBK1 complex is disrupted by PLpro-TM. Furthermore, SARS PLpro-TM reduces the levels of ubiquitinated forms of RIG-I, STING, TRAF3, TBK1, and IRF3 in the STING-TRAF3-TBK1 complex. These results collectively point to a new mechanism used by SARS-CoV through which PLpro negatively regulates IRF3 activation by interaction with STING-TRAF3-TBK1 complex, yielding a SARS-CoV countermeasure against host innate immunity.