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


CONCLUSIONS
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.
Lei
Yan-Chang
YC
Division of Clinical Immunology and Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, Hubei Province, China.
Tian
Yong-Jun
YJ
Ding
Hong-Hui
HH
Wang
Bao-Ju
BJ
Yang
Yan
Y
Hao
You-Hua
YH
Zhao
Xi-Ping
XP
Lu
Meng-Ji
MJ
Gong
Fei-Li
FL
Yang
Dong-Liang
DL
D000071480:APOBEC-3G Deaminase; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003564:Cytidine Deaminase; D043525:Cytosine Deaminase / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D004261:DNA Replication / Q000187:drug effects; D004279:DNA, Viral / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D006515:Hepatitis B virus / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008807:Mice, Inbred BALB C; D009700:Nucleoside Deaminases / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D010957:Plasmids / Q000235:genetics; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D014162:Transfection; D014779:Virus Replication / Q000187:drug effects*
D004279:DNA, Viral; D011994:Recombinant Proteins; D012097:Repressor Proteins; D009700:Nucleoside Deaminases; D043525:Cytosine Deaminase; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase