ScienceAsia 23 (1997): 041-050 |doi: 10.2306/scienceasia1513-1874.1997.23.041

EXPRESSION OF HEPATITIS B VIRUS SURFACE ANTIGEN IN COS-7 CELLS BY USING A RECOMBINANT pcDNA I VECTOR

KRUAVON BALACHANDRA¹, KASAMA SUPANARANOND¹, CHUENCHIT BOONCHIRD², NONGLUK BUDDHIRAKKUL¹, DUANTHANORM THAWARANANTHA¹, DUANGRAT JULLAKSORN¹, PRUKSWAN CHETANACHAN¹, JITTAPORN WATANASEREE³ AND SOMSAK PANTUWATANA⁴

ABSTRACT: A recombinant plasmid containing pre-S₂+S gene was constructed using pcDNAI plasmid as a vector. The constructed recombinant plasmid was transfected into COS-7 cells. It was shown that the hepatitis B virus surface antigen (HBsAg) was expressed in transfected COS-7 cells. The HBsAg could be rapidly detected within 24 hours and the antigen was accumulated in detectable level for two weeks after the transfection. In addition, the expressed HBsAg was composed of complete polypeptides of pre-S₂+S domain at MW. P25, GP28, GP33 and GP36 kDa. The synthesized polypeptides were assembled to form a spherical particle. These spherical particles were shown to have similar structure to those of plasma derived HBsAg under the electron microscope. The antibody specific to HBsAg reacted specifically to the expressed polypeptides. The results suggested that our recombinant HBsAg was morphologically and antigenically close to native HBsAg. Thus, our expression system may be considered as one of the alternative ways to modify the system to produce stable expression of HBsAg and leads to the production of vaccine or diagnostic kits.

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1 National Institute of Health, Department of Medical Sciences, Nonthaburi 11000.
2 Department of Biotechnology, Mahidol University, Thailand.
3 Government Pharmaceutical Organization, Thailand.
4 Department of Microbiology, Faculty of Science, Mahidol University, Thailand.

Received January 15, 1997