Screening and identification of dominant monoclonal HepG2 cell strain with 1.3-fold HBV genome.
Shijie Huaren Xiaohua Zazhi 2021;
29:934-944. [DOI:
10.11569/wcjd.v29.i16.934]
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Abstract
BACKGROUND
Hepatitis B virus (HBV) infection model in vitro is the basis for studying HBV life cycle and pathogenesis and for drug screening. With the clinical anti-HBV therapy entering the new trend of "functional cure" and "complete cure", there is an urgent need for cell models that can stably simulate the transcription mechanism of covalently closed circular DNA (cccDNA) and the role of hepatitis B virus X protein (HBx). The 1.3-fold HBV genome contains all the biological information of HBV. It can start the transcription process by its own promoter, support the formation of cccDNA, and complete viral replication, which is closest to the life cycle of HBV in vivo. Lentivirus transfection is a technology that takes lentivirus as vector and introduces foreign molecules such as DNA and RNA into eukaryotic cells, which can form stable transfection.
AIM
To construct a HepG2 cell model with 1.3-fold HBV genome by lentivirus transfection technology, and to screen and identify the dominant monoclonal strain that can stably and efficiently express HBV biomarkers.
METHODS
A lentiviral plasmid containing 1.3-fold HBV genome information was constructed, and the recombinant lentivirus culture was used to infect HepG2 cells at the optimal multiplicity of infection (MOI). Blasticidin (BSD) was used to select HepG2 cell strains (1.3-fold HBV-HepG2) stably integrating the 1.3-fold HBV genome, and then the HBV in the cell model was identified by PCR. HepG2 cells stably carrying the 1.3-fold HBV genome were cultured and nine candidate positive monoclones were selected. The flanking sequences of each monoclonal cell were sequenced to determine the insertion position of the corresponding HBV genome in the genome of HepG2 cells. The most dominant monoclones were selected according to the expression levels of HBsAg and HBeAg. The expression levels and stability of HBsAg, HBeAg, HBx, cccDNA, and HBV DNA in HepG2 cells stably carrying the 1.3-fold HBV genome were compared.
RESULTS
The lentiviral plasmid plenti-bsd-1.3-fold HBV was used to infect HepG2 cells at an MOI of 30. After 72 h, BSD (final concentration 1 μg/mL) was added for screening. After 15-20 d of continuous culture, stable 1.3-fold HBV-HepG2 cell line was obtained. HBV DNA sequence was then identified by PCR. Among the nine selected candidate positive monoclones, A14, in which the 1.3-fold HBV genome was inserted into the HepG2 genome at 1:166461695-166461715 (named HepGA14), had the highest expression levels of HBsAg and HBeAg at 24.28 IU/mL and 39.62 NCU/mL, respectively. HepGA14 can stably and highly express HBV biomarkers. Compared with HepG2.2.15 cell line, the expression levels of HBx and cccDNA in Hepga14 dominant monoclonal line in 1-20 passages were significantly higher (P < 0.05).
CONCLUSION
We have successfully constructed and screened HepGA14, a dominant monoclonal HepG cell strain with HBV 1.3-fold genome, which lays a good foundation for further research of HBV-host relationship and pathogenesis as well as for drug screening.
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