Hepatitis D virus dual-infection among Chinese hepatitis B patient related to hepatitis B surface antigen,hepatitis B virus DNA and age

The screening practices for hepatitis D virus(HDV)are diverse and nonstandardized worldwide,and the exact prevalence of HDV is uncertain.AIM To estimate HDV prevalence and investigate viral marker quantity trends in patients with hepatitis D.METHODS We collected 5594 serum samples from patients with hepatitis B in Jilin Province,China(3293 males and 2301 females,age range of 2 to 89 years).We then conducted tests for hepatitis B surface antigen(HBsAg),hepatitis B Virus(HBV)DNA,anti-hepatitis D antigen(HDAg),and HDV RNA.RESULTS We found that the prevalence of anti-HDAg and HDV RNA among hepatitis B patient were 3.6%(3.2-4.2%)and 1.2%(0.9-1.5%),respectively,87.69%of hepatitis D patients were 51-70 years old.HDV infection screening positive rate of patients with HBV DNA levels below 2000 IU/mL(2.0%)was higher than those above 2000 IU/mL(0.2%).Among anti-HDAg positive patients,the HDV RNA positive rate was positively correlated with the HBsAg level and anti-HDAg level.There was a weak correlation between HBsAg and anti-HDAg levels among hepatitis D patients.CONCLUSION Our study highlights the importance of considering multiple factors when assessing the severity of HDV infection,comprehensive evaluation of patients’clinical and laboratory parameters is necessary for proper diagnosis and treatment.

TRIM25 inhibits HBV replication by promoting HBx degradation and the RIG-I-mediated pgRNA recognition

Background:The hepatitis B virus(HBV)vaccine has been efficiently used for decades.However,hepatocellular carcinoma caused by HBV is still prevalent globally.We previously reported that interferon(IFN)-induced tripartite motif-containing 25(TRIM25)inhibited HBV replication by increasing the IFN expression,and this study aimed to further clarify the anti-HBV mechanism of TRIM25.Methods:The TRIM25-mediated degradation of hepatitis B virus X(HBx)protein was determined by detecting the expression of HBx in TRIM25-overexpressed or knocked-out HepG2 or HepG2-NTCP cells via Western blotting.Co-immunoprecipitation was performed to confirm the interaction between TRIM25 and HBx,and colocalization of TRIM25 and HBx was identified via immunofluorescence;HBV e-antigen and HBV surface antigen were qualified by using an enzyme-linked immunosorbent assay(ELISA)kit from Kehua Biotech.TRIM25 mRNA,pregenomic RNA(pgRNA),and HBV DNA were detected by quantitative real-time polymerase chain reaction.The retinoic acid-inducible gene I(RIG-I)and pgRNA interaction was verified by RNA-binding protein immunoprecipitation assay.Results:We found that TRIM25 promoted HBx degradation,and confirmed that TRIM25 could enhance the K90-site ubiquitination of HBx as well as promote HBx degradation by the proteasome pathway.Interestingly,apart from the Really Interesting New Gene(RING)domain,the SPRY domain of TRIM25 was also indispensable for HBx degradation.In addition,we found that the expression of TRIM25 increased the recognition of HBV pgRNA by interacting with RIG-I,which further increased the IFN production,and SPRY,but not the RING domain is critical in this process.Conclusions:The study found that TRIM25 interacted with HBx and promoted HBx-K90-site ubiquitination,which led to HBx degradation.On the other hand,TRIM25 may function as an adaptor,which enhanced the recognition of pgRNA by RIG-I,thereby further promoting IFN production.Our study can contribute to a better understanding of host-virus interaction.

Deubiquitinase ubiquitin-specific protease 3 (USP3) inhibits HIV-1 replication via promoting APOBEC3G (A3G) expression in both enzyme activity-dependent and -independent manners

Background: Ubiquitination plays an essential role in many biological processes, including viral infection, and can be reversed by deubiquitinating enzymes (DUBs). Although some studies discovered that DUBs inhibit or enhance viral infection by various mechanisms, there is lack of information on the role of DUBs in virus regulation, which needs to be further investigated.Methods: Immunoblotting, real-time polymerase chain reaction,in vivo/in vitro deubiquitination, protein immunoprecipitation, immunofluorescence, and co-localization biological techniques were employed to examine the effect of ubiquitin-specific protease 3 (USP3) on APOBEC3G (A3G) stability and human immunodeficiency virus (HIV) replication. To analyse the relationship between USP3 and HIV disease progression, we recruited 20 HIV-infected patients to detect the levels of USP3 and A3G in peripheral blood and analysed their correlation with CD4^(+) T-cell counts. Correlation was estimated by Pearson correlation coefficients (for parametric data).Results: The results demonstrated that USP3 specifically inhibits HIV-1 replication in an A3G-dependent manner. Further investigation found that USP3 stabilized 90% to 95% of A3G expression by deubiquitinating Vif-mediated polyubiquitination and blocking its degradation in an enzyme-dependent manner. It also enhances the A3G messenger RNA (mRNA) level by binding to A3G mRNA and stabilizing it in an enzyme-independent manner. Moreover, USP3 expression was positively correlated with A3G expression (r= 0.5110) and CD4^(+) T-cell counts (r= 0.5083) in HIV-1-infected patients.Conclusions: USP3 restricts HIV-1 viral infections by increasing the expression of the antiviral factor A3G. Therefore, USP3 may be an important target for drug development and serve as a novel therapeutic strategy against viral infections.

IFN-β1b induces OAS3 to inhibit EV71 via IFN-β1b/JAK/STAT1 pathway

Enterovirus 71(EV71) caused hand, foot and mouth disease(HFMD) is a serious threat to the health of young children. Although type I interferon(IFN-I) has been proven to control EV71 replication, the key downstream IFNstimulated gene(ISG) remains to be clarified and investigated. Recently, we found that 2’-5’-oligoadenylate synthetases 3(OAS3), as one of ISG of IFN-β1b, was antagonized by EV71 3C protein. Here, we confirm that OAS3is the major determinant of IFN-β1b-mediated EV71 inhibition, which depends on the downstream constitutive RNase L activation. 2’-5’-oligoadenylate(2-5A) synthesis activity deficient mutations of OAS3 D816A, D818A,D888A, and K950A lost resistance to EV71 because they could not activate downstream RNase L. Further investigation proved that EV71 infection induced OAS3 but not RNase L expression by IFN pathway. Mechanically, EV71 or IFN-β1b-induced phosphorylation of STAT1, but not STAT3, initiated the transcription of OAS3 by directly binding to the OAS3 promoter. Our works elucidate the immune regulatory mechanism of the host OAS3/RNase L system against EV71 replication.

A dual-role of SARS-CoV-2 nucleocapsid protein in regulating innate immune response

The recently emerged severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),which is the causative agent of ongoing global pan demic of COVID-19,may trigger imm uno suppression in the early stage and overactive immune resp onse in the late stage of infection;However,the un derlying mecha nisms are not well understood.Here we dem on strated that the SARS-CoV-2 nucleocapsid(N)protein dually regulated innate immune responses,i.e.,the low-dose N protein suppressed type I interferon(IFN-I)signaling and inflammatory cytokines,whereas high-dose N protein promoted IFN-I signaling and inflammatory cytokines.Mechanistically,the SARS-CoV-2 N protein dually regulated the phosphorylation and nuclear translocation of IRF3,STAT1,and STAT2.Additi on ally,low-dose N protein combined with TRIM25 could suppress the ubiquitination and activatio n of retinoic acidinducible gene I(RIG-I).Our findings revealed a regulatory mechanism of innate immune responses by the SARS-CoV-2 N protein,which would contribute to understanding the pathogenesis of SARS-CoV-2 and other SARS-like coronaviruses,and development of more effective strategies for controlling COVID-19.

Legionella pneumophila temporally regulates the activity of ADP/ATP translocases by reversible ADP-ribosylation

The mitochondrion is an important signaling hub that governs diverse cellular functions,including metabolism,energy production,and immunity.Among the hundreds of effectors translocated into host cells by the Dot/Icm system of Legionella pneumophila,several are targeted to mitochondria but the function of most of them remains elusive.Our recent study found that the effector Ceg3 inhibits the activity of ADP/ATP translocases(ANTs)by ADP-ribosylation(ADPR).Here,we show that the effect of Ceg3 is antagonized by Larg1,an effector encoded by lpg0081,a gene that is situated next to ceg3.Larg1 functions to reverse Ceg3-mediated ADPR of ANTs by cleaving the N-glycosidic bond between the ADPR moiety and the modified arginine residues in ANTs,leading to restoration of their activity in ADP/ATP exchange.Structural analysis of Larg1 and its complex with ADPR reveals that this ADPR glycohydrolase harbors a unique macrodomain that catalyzes the removal of ADPR modification on ANTs.Our results also demonstrate that together with Ceg3,Larg1 imposes temporal regulation of the activity of ANTs by reversible ADPR during L.pneumophila infection.