Multi-copy introduction and high-level expression of interleukin-3 genes by retroviral vector superinfection.
We constructed a retroviral expression vector carrying multiple cloning sites. This vector was found to express efficiently the cloned gene. Using this vector and a helper virus-free system, a murine interleukin-3 (mlL-3) high-producing cell line was established by multiple cycles of infection with recombinant retroviruses carrying mlL-3 cDNA. The infected cells produced a considerable amount of mlL-3 and the concentration of mlL-3 in culture media increased as a function of the frequency of infection. High levels of mlL-3 cDNA, mRNA and protein in this cell line were confirmed by Southern, Northern and biological assays, respectively. These results suggest that artificial gene amplification is possible in a helper-free retroviral system. This should be applicable to efficient expression of bioactive molecules in a wide variety of mammalian cells including suspension cells.
Tsuchiya
T
T
Department of Genetics, University of Tokyo, Japan.
Tojo
A
A
Shibuya
M
M
D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D005818:Genetic Engineering; D005822:Genetic Vectors; D007377:Interleukin-3 / Q000235:genetics*; D051379:Mice; D011994:Recombinant Proteins; D012190:Retroviridae / Q000235:genetics; D015163:Superinfection
D007377:Interleukin-3; D011994:Recombinant Proteins