[Chromosome aberration and carcinogenicity of CHO dhfr- cells transformed by plasmid containing S+ and Pre S1 of fusion gene of hepatitis B virus].

Objective To investigate the chromosome aberrations and carcinogenicity of CHO dhfr - cell induced by integration of plasmid containing S+ and Pre S1 fusion gene of hepatitis B surface antigen(HBsAg).Methods The plasmid pCHBSS1G was constructed with S+ Pre S1 of HBsAg.CHO dhfr - cells were transformed with this recombinant plasmid DNA and CHO cells lines with integrated DNA were cloned and named GdSS1 18.The GdSS1 18 cell lines secreting the S+ Pre S1 fusion protein of HBsAg at high level were developed by screening in increased concentration of MTX and MSX in cultured media.To make sample of cells chromosome,the cells integrated DNA were subcutaneously injected into nude mouse.Results The CHO dhfr - cell lines integrated with S and Pre S1 fusion protein of HBsAg were developed and named GdSS1 18 cell lines.The frequencies and type of chromosome aberrations of the GdSS1 18 cell lines with different passage generations were 11%,56% and 29%,respectively,while that of the control CHO dhfr - cell lines was 6%.There was no change in the mode of chromosomes,both cell lines having 20 chromosomes.Both cell lines were non oncogenic in nude mouse.Conclusion The chromosome aberration of CHO dhfr - cells with integrated DNA were obviously higher than that of the original CHO dhfr - cells without integrated DNA.Both cell lines were non oncogenic in nude mouse.