In vitro production of Helicoverpa baculovirus biopesticides—Automated selection of insect cell clones for manufacturing and systems biology studies

Baculovirus pesticides are increasingly being used as effective biological control agents against caterpillar pests worldwide. Increasing occlusion body (OB) yields per cell in culture is the main challenge to enable commercialization of in vitro production of baculovirus pesticides. Isolating clones from a heterogeneous cell population may allow development of a high virus producing cell clone. To date, the selection of insect clones has been based mainly on laborious cell serial dilution methods which create few viable clones. This work used an automated robotic clone picking system to establish over 250 insect clones of a Helicoverpa zea cell population to be screened for virus production. However, the higher producing clones only produced 10-30% higher OB yields than the original cell population. This study suggested that unless screening of thousands of clones is performed, obtaining a 2-fold increase in OB/cell yield compared to the parent population is unlikely. Nevertheless, it creates pure clones for manufacturing. In addition, two clones that were at least 2-3 times different in OB yields were isolated. Hence, this method can create a high contrast system (OB/cell yield basis), for comparative studies using a systems biology approach, which should inform a more targeted approach to engineer genetically a production cell line.