title: [Application of dhfr gene negative Chinese hamster ovary cell line to express hepatitis B virus surface antigen].
abstract: OBJECTIVE
  To set up an efficient expressing system for recombinant hepatitis B virus surface antigen (HBsAg) in dhfr gene negative CHO cell line.
  
  
  METHODS
  HBsAg gene expressing plasmid pCI-dhfr-S was constructed by integrating HBsAg gene into plasmid pCI which carries dhfr gene. The HBsAg expressing cell line was set up by transfection of plasmid pCI-dhfr-S into dhfr gene negative CHO cell line in the way of lipofectin.
  
  
  RESULTS
  Under the selective pressure of MTX, 18 of 28 clonized cell lines expressed HBsAg, 4 of them reached a high titer of 1:32 and protein content 1-3 micrograms/ml.
  
  
  CONCLUSIONS
  In this study, the high level expression of HBsAg demonstrated that the dhfr negative mammalian cell line when recombined with plasmid harboring the corresponding deleted gene can efficiently express the foreign gene. The further steps toward building optimum conditions of the expressing system and the increase of expressed product are under study.
authors: Department of Hepatitis, Institute of Virology, Chinese Academy of Preventive Medicine, Beijing 100052, China.
authors: Y
authors: Y
authors: Yi
authors: M
authors: M
authors: Zhang
authors: C
authors: C
authors: Liu
mesh_terms: D000818:Animals; D001483:Base Sequence; D016466:CHO Cells / Q000378:metabolism*; D006224:Cricetinae; D006514:Hepatitis B Surface Antigens / Q000096:biosynthesis* / Q000235:genetics; D010957:Plasmids; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics*
chemical_list: D006514:Hepatitis B Surface Antigens; D013762:Tetrahydrofolate Dehydrogenase