Inhibition of hepatitis B virus replication by APOBEC3G in vitro and in vivo

AIM： To investigate the effect of APOBEC3G mediated antiviral activity against hepatitis B virus （HBV） in cell cultures and replication competent HBV vector-based mouse model. METHODS： The mammalian hepatoma cells Huh7 and HepG2 were cotransfected with various amounts of CMV-driven expression vector encoding APOBEC3G and replication competent 1.3 fold over-length HBV. Levels of HBsAg and HBeAg in the media of the transfected cells were determined by ELISA. The expression of HBcAg in transfected cells was detected by western blot. HBV DNA and RNA from intracellular core particles were examined by Northern and Southern blot analyses. To assess activity of the APOBEC3G in vivo, an HBV vector-based model was used in which APOBEC3G and the HBV vector were co-delivered via high-volume tail vein injection. Levels of HBsAg and HBV DNA in the sera of mice as well as HBV core-associated RNA in the liver of mice were determined by ELISA and quantitative PCR analysis respectively. RESULTS： There was a dose dependent decrease in the levels of intracellular core-associated HBV DNA and extracellular production of HBsAg and HBeAg. The levels of intracellular core-associated viral RNA also decreased, but the expression of HBcAg in transfected cells showed almost no change. Consistent with in vitro results, levels of HBsAg in the sera of mice were dramatically decreased. More than 1.5 log10 decrease in levels of serum HBV DNA and liver HBV RNA were observed in the APOBEC3G-treated groups compared with the control groups.CONCLUSION： These findings indicate that APOBEC3G could suppress HBV replication and antigen expression both in vivo and in vitro, promising an advance in treatment of HBV infection.

Gut Microbiota Reconstruction Following Host Infection with Bloodstage Plasmodium berghei ANKA Strain in a Murine Model

Malaria remains a global health problem.The relationship between Plasmodium spp.and the gut microbiota as well as the impact of Plasmodium spp.on the gut microbiota in vertebrate hosts is unclear.The aim of the current study was to evaluate the effect of blood-stage Plasmodium parasites on the gut microbiota of mice.The gut microbiota was analyzed by 16S rRNA sequencing and bioinformatic analyses at three stages.The gut microbiota changed during the three phases:the healthy stage,the infection stage,and the cure stage(on the 9th day after malarial elimination).Moreover,the gut microbiota of these infected animals did not recover after malaria infection.There were 254 operational taxonomic units(OTUs)across all three stages,and there were unique strains or OTUs at each stage of the experiment.The percentages of community abundance of 8 OTUs changed significantly(P<0.05).The dominant OTU in both the healthy mice and the mice with malaria was OTU265,while that in the cured mice was OTU234.In addition,the changes in OTU147 were the most noteworthy.Its percentage of community abundance varied greatly,with higher values during malaria than before malaria infection and after malaria elimination.These results indicated that the external environment influenced the gut microbiota after host C57BL/6 mice were infected with blood-stage P.berghei ANKA and that the same was true during and after elimination of blood-stage P.berghei ANKA.In addition,we could not isolate OTU147 for further study.This study identified gut microbiota components that were reconstructed after infection by and elimination of blood-stage P.berghei ANKA in host C57BL/6 mice,and this process was affected by P.berghei ANKA and the external environment of the host.

N-terminal and C-terminal cytosine deaminase domain of APOBEC3G inhibit hepatitis B virus replication

AIM: To investigate the effect of human apolipoprotein B mRNA-editing enzyme catalytic-polypeptide 3G (APOBEC3G) and its N-terminal or C-terminal cytosine deaminase domain-mediated antiviral activity against hepatitis B virus (HBV) in vitro and in vivo. METHODS: The mammalian hepatoma cells HepG2 and HuH7 were cotransfected with APOBEC3G and its N-terminal or C-terminal cytosine deaminase domain expression vector and 1.3-fold-overlength HBV DNA as well as the linear monomeric HBV of genotype B and C. For in vivo study, an HBV vector-based mouse model was used in which APOBEC3G and its N-terminal or C-terminal cytosine deaminase domain expression vectors were co-delivered with 1.3-fold-overlength HBV DNA via high-volume tail vein injection. Levels of hepatitis B virus surface antigen (HBsAg) and hepatitis B virus e antigen (HBeAg) in the media of the transfected cells and in the sera of mice were determined by ELISA.The expression of hepatitis B virus core antigen (HBcAg) in the transfected cells was determined by Western blot analysis. Core-associated HBV DNA was examined by Southern blot analysis. Levels of HBV DNA in the sera of mice as well as HBV core-associated RNA in the liver of mice were determined by quantitative PCR and quantitative RT-PCR analysis, respectively. RESULTS: Human APOBEC3G exerted an anti-HBV activity in a dose-dependent manner in HepG2 cells, and comparable suppressive effects were observed on genotype B and C as that of genotype A. Interestingly, the N-terminal or C-terminal cytosine deaminase domain alone could also inhibit HBV replication in HepG2 cells as well as Huh7 cells. Consistent with in vitro results, the levels of HBsAg in the sera of mice were dramatically decreased, with more than 50 times decrease in the levels of serum HBV DNA and core-associated RNA in the liver of mice treated with APOBEC3G and its N-terminal or C-terminal cytosine deaminase domain as compared to the controls. CONCLUSION: Our findings provide probably the first evidence showing that APOBEC3G and its N-terminal or C-terminal cytosine deaminase domain could suppress HBV replication in vitro and in vivo.