The sf32 unique gene of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) is a non-essential gene that could be involved in nucleocapsid organization in occlusion-derived virions

PLoS One. 2013 Oct 30;8(10):e77683. doi: 10.1371/journal.pone.0077683. eCollection 2013.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • DNA, Viral / genetics
  • Genes, Essential / genetics
  • Genome, Viral / genetics
  • Genotype
  • Larva / virology
  • Nucleocapsid / genetics*
  • Nucleopolyhedroviruses / genetics*
  • Spodoptera / virology*
  • Viral Proteins / genetics
  • Virion / genetics*
  • Virus Replication / genetics

Substances

  • DNA, Viral
  • Viral Proteins

Grants and funding

This study received financial support from the Spanish Ministry for Science and Technology (AGL2008-05456-C03-01, AGL2011-30352-C02-01). I.B. received a CSIC studentship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.