Annual Report 2006

cultured cell line (NIAS-Bm-Ke1)
that adjusted to serum-free media
Shigeo IMANISHI 1) , Gaku AKIDUKI 1) , Yoshiya YOSHIDA 2) and
Chun Ying YANG 2)
1) Insect Biotechnology and Sericology Development
2) Kohjin Bio Co.Ltd. Biology and Immunology Department
Both Sf9 cell line derived from
and High 5 cell line derive from
are utilized actually as a gene
expression system by baculovirus
However, there is not cell line
that is suitable for serum-free culture and high
level gene expression. This time, we established
cell line that is almost equal to
cell line and leaded to
develop a new gene expression system
that can actualize a large scale production of
recombinant protein.
NIAS-Bm-Ke1 cell line (Ke1 cells) that
adjusted to KBM700 of serum-free media was
established. Ke1 cells showed high cell proliferation
and high susceptibility to BmPTLNPV, a
recombinant BmNPV expressing the luciferase
gene (Figs. 1, 2).
The heat-treated silkworm hemolymph
showed a role of promoter of susceptibility of
recombinant BmNPV when added to Ke1 cells
cultured in serum-free medium. In comparison
of luciferase gene expression of Ke1 cells and Sf
9 cells, Ke1 cells cultured in KBM700 serumfree
medium containing heat-treated silkworm
hemolymph, showed higher luciferase activity
than Sf9 cells cultured in SF900 serum-free
medium containing 10% of FBS. A large scale
luciferase expression in spinner culture was
possible when Ke1 cells were cultured in KBM
700 serum-free medium containing heat-treated
silkworm hemolymph, because Ke1 cells were
floatage ( Fig. 3 ) . Heat-treated silkworm
hemolymph was eliminated from KBM700
serum-free medium at 24 hours after the virus
inoculation and cultured in fresh KBM700
serum-free medium. As a conclusion, it was
shown that NIAS-Bm-Ke1 cell line was able to
be used as baculovirus gene expression system.
Fig. 1
NIAS-Bm-Kel cell line derived from
embryo (serum-free)
Fig. 2
Formation of BmNPV polyhedra in ke1 cells
(serum-free media+heat-treated silkworm hemolymph
1 % volume)