(Public Library of Science, 2013) Beperet Arive, Inés; Barrera Cubillos, Gloria Patricia; Simón de Goñi, Oihane; Williams, Trevor; López Ferber, Miguel; Gasmi, Laila; Herrero, Salvador; Caballero Murillo, Primitivo; Nekazaritza Ekoizpena; Producción Agraria; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
A recombinant virus lacking the sf32 gene (Sf32null), unique to the Spodoptera frugiperda multiple nucleopolyhedrovirus
(SfMNPV), was generated by homologous recombination from a bacmid comprising the complete viral genome (Sfbac).
Transcriptional analysis revealed that sf32 is an early gene. Occlusion bodies (OBs) of Sf32null contained 62% more genomic
DNA than viruses containing the sf32 gene, Sfbac and Sf32null-repair, although Sf32null DNA was three-fold less infective
when injected in vivo. Sf32null OBs were 18% larger in diameter and contained 17% more nucleocapsids within ODVs than
those of Sfbac. No significant differences were detected in OB pathogenicity (50% lethal concentration), speed-of-kill or
budded virus production in vivo. In contrast, the production of OBs/larva was reduced by 39% in insects infected by Sf32null
compared to those infected by Sfbac. The SF32 predicted protein sequence showed homology (25% identity, 44% similarity)
to two adhesion proteins from Streptococcus pyogenes and a single N-mirystoylation site was predicted. We conclude that
SF32 is a non-essential protein that could be involved in nucleocapsid organization during ODV assembly and occlusion,
resulting in increased numbers of nucleocapsids within ODVs.
