A recombinant Anticarsia gemmatalis MNPV harboring chiA and v-cath genes from Choristoneura fumiferana defective NPV induce host liquefaction and increased insecticidal activity

PLoS One. 2013 Sep 25;8(9):e74592. doi: 10.1371/journal.pone.0074592. eCollection 2013.

Abstract

One of the interesting features of Anticarsia gemmatalis multiple nucleopolyhedrovirus isolate 2D (AgMNPV-2D) genome is the absence of chitinase (chiA) and cathepsin (v-cath) genes. This characteristic may be responsible for the lack of liquefaction and melanization in A. gemmatalis larvae killed by AgMNPV-2D infection. This study aimed to test the hypothesis that CHIA and V-CATH proteins from Choristonera fumiferana DEF multiple nucleopolyhedrovirus (CfDEFNPV) are able to liquefy and melanize the cuticle of A. gemmatalis larvae infected by a recombinant AgMNPV containing chiA and v-cath genes inserted in its genome. A fragment from the CfDefNPV genome containing chiA and v-cath genes was inserted into the genome of AgMNPV-2D. The recombinant virus (vAgp2100Cf.chiA/v-cath) was purified and used to infect insect cells and larvae. Transcripts of v-cath and chiA genes were detected along the infection of insect cells by qRT-PCR, from early to late phases of infection. The analysis of A. gemmatalis larvae killed by vAgp2100Cf.chiA/v-cath infection confirmed the hypothesis proposed. The vAgp2100Cf.chiA/v-cath showed higher insecticidal activity against third instar A. gemmatalis larvae when compared to AgMNPV-2D. The mean time to death was also lower for the vAgp2100Cf.chiA/v-cath when compared to AgMNPV-2D at 10 days post infection. Occlusion body production was higher in A. gemmatalis larvae infected with vAgp2100Cf.chiA/v-cath when compared to AgMNPV-2D. Enzyme assays showed higher chitinase and cysteine protease activities in insect cells and insects infected with vAgp2100Cf.chiA/v-cath when compared to AgMNPV-2D. The introduction of chiA and v-cath genes into the genome of AgMNPV improves its insecticidal activity against A. gemmatalis larvae and this recombinant virus could be used as an alternative to the wild type virus to control this important insect pest.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cathepsins / metabolism
  • Cell Line
  • Chitinases / metabolism
  • Cysteine Endopeptidases / metabolism
  • Genes, Viral / genetics*
  • Genetic Loci
  • Host-Pathogen Interactions* / drug effects
  • Host-Pathogen Interactions* / genetics
  • Inclusion Bodies / drug effects
  • Inclusion Bodies / metabolism
  • Inhibitory Concentration 50
  • Insecticides / pharmacology*
  • Larva / drug effects
  • Larva / virology
  • Lepidoptera / virology*
  • Nucleopolyhedroviruses / drug effects
  • Nucleopolyhedroviruses / genetics*
  • Recombination, Genetic*
  • Time Factors
  • Transcription, Genetic / drug effects

Substances

  • Insecticides
  • Chitinases
  • Cathepsins
  • Cysteine Endopeptidases

Grants and funding

Consenho Nacional de Desenvolvimento Científico e Tecnológico (www.cnpq.br) grant numbers 475579/2010-0 and 490253/2011-3, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (www.capes.gov.br) grant number AUXPE-PROCAD/NF 886/2010, Fundação de Apoio à Pesquisa do Distrito Federal (www.fap.df.gov.br) grant number: 193.000.583/2009. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.