Insect Cells and Larvae, Gene Expression Systems

The use of the insect cell-baculovirus system has grown significantly over the past three decades. The present chapter elucidates the fundamentals, scientific developments, technologies, and hurdles encountered in this field. The common types of insects and insect lines used as well as their specific features and culture conditions are described. Additionally, the types of baculoviruses used and the methods for generating them are also revealed. Particular emphasis has been given to describing the construction of recombinant baculoviruses that are used in production of heterologous proteins with insect cells. A major advantage in using insect cells is their ability to perform many post-translational processing events on these proteins including glycosylation. The types of insect cell glycosylation and the differences in glycosylation patterns between insect and mammalian systems are detailed. The parameters that affect insect cell growth and baculovirus infection including bioreactor configuration, process monitoring and control, oxygen supply, sparging, and media formulations are described. In particular, cell culture processing methods including batch, fed-batch, perfusion, and semi-batch processes are illustrated. Additional factors affecting baculovirus infection including multiplicity, time of infection, and the generation of mutant viruses are also considered. A final section is devoted to the use of insect larvae in combination with baculovirus as a potentially alternative to cell culture for the low-cost generation of baculoviruses and heterologous proteins. With all the advances in molecular biology and engineering processes for the baculovirus-insect cell system, insect cell culture and its application to recombinant protein production, vaccines, pesticides, and other areas will continue to expand in the coming decades. Keywords: baculovirus; High Five™; polyhedrin; defective interfering particle; baculovirus expression vector system (BEVS)