25. The MOI indicates the ratio of plaque-forming units (pfu) at
the time of the infection of the cells. For the viral infection of
insect cells, a MOI between 0.01 and 1 should be chosen, as a
low MOI reduces the number of defective viral particles [12–
14].
26. The remaining volume of the syringe should be filled with air
(under sterile conditions), so that the virus suspension does not
remain in the tube when the reactor is infected.
27. Bioreactor sampling has been described previously in Animal
Cell Biotechnology - Methods and Protocols in 2019 by K€ aßer
et al. [8].
28. The time of harvest is one of the most important factors in
protein production when using a lytic production strategy, and
usually depends on the viability of infected cells. Harvesting
can be indicated by a drop in viability (i.e., viability below 90%)
due to the baculovirus-related late expression promoter. Harvesting before an observed viability loss can result in a poor
protein yield. Harvesting too late (i.e., viability below 70%) can
result in poor protein yield too, due to cell lysis-related protein
degradation.
Acknowledgments
We would like to thank the Hessen State Ministry of Higher
Education, Research and the Arts for the financial support within
the Hessen initiative for scientific and economic excellence
(LOEWE-Program, LOEWE ZIB (Center for Insect Biotechnology and Bioresources) and LOEWE Center DRUID (Novel Drug
Targets against Poverty-Related and Neglected Tropical Infectious
Diseases)). The authors acknowledge Catherine Meckel-Oschmann
for revising the chapter.
References
1. Felberbaum RS (2015) The baculovirus
expression vector system: a commercial
manufacturing platform for viral vaccines and
gene therapy vectors. Biotechnol J 10
(5):702–714. https://doi.org/10.1002/biot.
201400438
2. Tomiya N, Narang S, Lee YC et al (2004)
Comparing N-glycan processing in mammalian
cell lines to native and engineered lepidopteran
insect cell lines. Glycoconj J 21(6):343–360.
https://doi.org/10.1023/B:GLYC.
0000046275.28315.87
3. Kost TA, Condreay JP (2002) Recombinant
baculoviruses as mammalian cell gene-delivery
vectors. Trends Biotechnol 20(4):173–180
https://doi.org/10.1016/S0167-7799(01)
01911-4
4. Grein TA, Loewe D, Dieken H et al (2018)
High titer oncolytic measles virus production
process by integration of dielectric spectroscopy as online monitoring system. Biotechnol
Bioeng 115(5):1186–1194. https://doi.org/
10.1002/bit.26538
5. Zitzmann J, Weidner T, Eichner G et al (2018)
Dielectric spectroscopy and optical density
measurement for the online monitoring and
control of recombinant protein production in
stably transformed drosophila melanogaster S2
Antigen Production in Insect Cells
117
the time of the infection of the cells. For the viral infection of
insect cells, a MOI between 0.01 and 1 should be chosen, as a
low MOI reduces the number of defective viral particles [12–
14].
26. The remaining volume of the syringe should be filled with air
(under sterile conditions), so that the virus suspension does not
remain in the tube when the reactor is infected.
27. Bioreactor sampling has been described previously in Animal
Cell Biotechnology - Methods and Protocols in 2019 by K€ aßer
et al. [8].
28. The time of harvest is one of the most important factors in
protein production when using a lytic production strategy, and
usually depends on the viability of infected cells. Harvesting
can be indicated by a drop in viability (i.e., viability below 90%)
due to the baculovirus-related late expression promoter. Harvesting before an observed viability loss can result in a poor
protein yield. Harvesting too late (i.e., viability below 70%) can
result in poor protein yield too, due to cell lysis-related protein
degradation.
Acknowledgments
We would like to thank the Hessen State Ministry of Higher
Education, Research and the Arts for the financial support within
the Hessen initiative for scientific and economic excellence
(LOEWE-Program, LOEWE ZIB (Center for Insect Biotechnology and Bioresources) and LOEWE Center DRUID (Novel Drug
Targets against Poverty-Related and Neglected Tropical Infectious
Diseases)). The authors acknowledge Catherine Meckel-Oschmann
for revising the chapter.
References
1. Felberbaum RS (2015) The baculovirus
expression vector system: a commercial
manufacturing platform for viral vaccines and
gene therapy vectors. Biotechnol J 10
(5):702–714. https://doi.org/10.1002/biot.
201400438
2. Tomiya N, Narang S, Lee YC et al (2004)
Comparing N-glycan processing in mammalian
cell lines to native and engineered lepidopteran
insect cell lines. Glycoconj J 21(6):343–360.
https://doi.org/10.1023/B:GLYC.
0000046275.28315.87
3. Kost TA, Condreay JP (2002) Recombinant
baculoviruses as mammalian cell gene-delivery
vectors. Trends Biotechnol 20(4):173–180
https://doi.org/10.1016/S0167-7799(01)
01911-4
4. Grein TA, Loewe D, Dieken H et al (2018)
High titer oncolytic measles virus production
process by integration of dielectric spectroscopy as online monitoring system. Biotechnol
Bioeng 115(5):1186–1194. https://doi.org/
10.1002/bit.26538
5. Zitzmann J, Weidner T, Eichner G et al (2018)
Dielectric spectroscopy and optical density
measurement for the online monitoring and
control of recombinant protein production in
stably transformed drosophila melanogaster S2
Antigen Production in Insect Cells
117