Objective In the previous research, a monoclonal cell line RIRI-PaDe-2-C6 was established from Papilio demoleus cell line RIRI-PaDe-2 and it was found that the two cell lines could be infected by wild-type Autographa californica multiple nucleopolyhedrosis virus (AcMNPV). Especially, RIRI-PaDe-2-C6 was susceptible to AcMNPV and exhibited a higher production of AcMNPV polyhedral per infected cell averagely compared to the parent RIRI-PaDe-2 cells. The aim of this study is to further understand the characteristics of RIRI-PaDe-2-C6 in expressing exogenous genes.

Method The Bac-to-Bac baculovirus expression system was used to establish recombinant baculovirus carrying β-galactosidase gene and secreted alkaline phosphatase (SEAP) gene. The RIRI-PaDe-2-C6 was infected with recombinant virus. The expression levels of the two recombinant proteins were detected at 24, 48, 72, 96, 120, 144, and 168 hours after infection and compared with RIRI-PaDe-2 cells. The methods of cells morphology analysis, growth analysis and chromosome analysis were used to obtain the biological characteristics of RIRI-PaDe-2-C6.

Result RIRI-PaDe-2-C6 and RIRI-PaDe-2 could be infected by recombinant baculovirus. The expression of β-galactosidase (β-Gal) was significantly higher than that of RIRI-PaDe-2 (P < 0.05), but no significant difference in expression level of secreted alkaline phosphatase (SEAP) was observed between RIRI-PaDe-2-C6 and RIRI-PaDe-2 (P>0.05). All cells were spindle-shaped in RIRI-PaDe-2-C6 which was more homogeneous than RIRI-PaDe-2. The cell population doubling time of RIRI-PaDe-2-C6 was 94.94 hours which was longer than those of RIRI-PaDe-2 (67.42 hous). The averages chromosome numbers of RIRI-PaDe-2-C6 was 52.26±30.48 which was significant different from that of RIRI-PaDe-2 (73.19±24.27).

Conclusion The differences in expressing exogenous genes and biological characteristics are significant between clone cell line RIRI-PaDe-2-C6 and its parent cell line RIRI-PaDe-2.