Isolation of a Baculovirus Variant That Exhibits Enhanced Polyhedra Production Stability during Serial Passage in Cell Culture

Abstract

The formation of few polyhedra mutants during serial propagation of baculoviruses in cell culture encumbers commercial scale production in this system. ALymantria disparnuclear polyhedrosis virus (LdMNPV) variant (isolate A21-MPV) has been isolated and the traits of budded virus (BV) production, synthesis of polyhedra, the percentage of cells that produce polyhedra, and the formation of few polyhedra (FP) mutants were investigated during serial passage of the variant inL. dispar652Y cells. Isolate A21-MPV exhibited stable levels of BV production and polyhedra production and a small increase in the percentage of cells that produced polyhedra during five serial passages in cell culture. In contrast, isolate A21, a wild-type isolate, exhibited a significant increase in BV production and a decrease in polyhedra production and in the number of cells that produced polyhedra during five serial passages. The traits exhibited by isolate A21 are typically observed when FP mutants are formed and become predominate in a virus population. After five serial passages, greater than 95% of isolate A21 virus exhibited a FP phenotype. In contrast, less than 8% of isolate A21-MPV exhibited a FP phenotype after five serial passages. These results indicate that isolate A21-MPV exhibits enhanced polyhedra production stability during serial passage in Ld652Y cells. Consequently, this isolate could be useful for large-scale production in cell culture systems.