Characterization of the proteins from occlusion bodies of baculoviruses with activity against the fall armyworm Spodoptera frugiperda

Abstract

The fall armyworm Spodoptera frugiperda causes severe yield losses in maize and its control has been based on the use of chemical insecticides mostly. The proteins of occlusion bodies, occlusion-derived virions, chitinase activity and the chitinase gene were analyzed in seven baculovirus SfNPV strains isolated from S. frugiperda, SfNPV-Ar, SfNPV-Fx, SfNPVHo, SfNPV-Sin, SfNPV-An1, SfNPV-An2, and SfNPV-Gto. The strains with the lowest amounts of proteins detected were SfNPV-Ar and SfNPV-Gto, a high chitinase activity was detected in both strains and the SfNPV-An2 strain. The chitinase gene sequences were identified in the genomes of SfNPV-Ar, SfNPV-Fx, SfNPV-Ho, SfNPV-Sin and SfNPV-An1 strains, all sequences showed a change from LEU to ILE in the active site, a signal peptide and a retention motif, except for the SfNPV-Ho strain. The chitinase gene phylogeny showed a close relationship between all SfNPV chitinases. These results showed that the most virulent SfNPV strains have chitinase activity and fewer proteins, this will affect the virulence and virus-insect interaction, making the SfNPV-Ar, SfNPV-Gto and SfNPV-An2 great candidates for the control of the fall armyworm.