Selection of Anticarsia gemmatalis nucleopolyhedrovirus variants for the in vitro production of a biopesticide

The Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) has been used as a biopesticide to control the “soybean caterpillar” in Brazil. Production of baculoviruses has been performed in vivo through the infection of larvae under laboratory conditions. The in vitro production has been limited by the occurrence of mutations and deletions in viral isolates following serial passages in cell culture. This study aimed to select productive and genetically stable AgMNPV isolates suitable for in vitro production. Initially six variants with high polyhedra production in cell culture (Many Polyhedra - MP) were selected through plaque assay purification. The molecular characterization of isolates was performed by DNA restriction analysis and protein synthesis analysis. The two most productive isolates after serial passages were further analyzed in cell suspension cultures, using IPLB-SF21 cells adapted to Sf900II medium. Occlusion body (OB) production was monitored daily to evaluate potential for in vitro biopesticide manufacturing. The MP variants did not present molecular alterations compared to the type-isolate AgMNPV-2D. Among the variants, the AgMNPV-MP5 isolate showed the highest productivity yielding 5.3 × 108 OBs/mL and approximately 300 OBs/cell after eight days of infection. These results indicate AgMNPV-MP5 as a possible candidate for biopesticide production.