A Recombinant Anticarsia gemmatalis MNPV Harboring chiA and v-cath Genes from Choristoneura fumiferana Defective NPV Induce Host Liquefaction and Increased Insecticidal Activity

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.

Complete genome sequence and structural characterization of a novel iflavirus isolated from Opsiphanes invirae (Lepidoptera: Nymphalidae)

“…invirae, no viruses have been isolated from this insect (Lemos et al, 2009a(Lemos et al, , 2009bLima et al, 2013;Ribeiro et al, 2010;Tinôco, 2008).…”

Proteomic analysis of the occlusion-derived virus of Clostera anachoreta granulovirus

“…Furthermore, cathepsin is synthesized as a proenzyme and later cleaved to produce the mature form, which seems to be assisted by chitinase (Hom et al, 2002). The introduction of chitinase and cathepsin genes into the AgMNPV genome induced host liquefaction and increased insecticidal activity (Lima et al, 2013). In this study, chitinase and cathepsin were identified as components of the ClanGV ODV particle.…”

Reaching the melting point: Degradative enzymes and protease inhibitors involved in baculovirus infection and dissemination

“…Notably, Anticarsia gemmatalis MNPV (AgMNPV), an alphabaculovirus closely related to AcMNPV, lacks both chitinase and cathepsin (Table). As expected, AgMNPV-infected Anticarsia gemmatalis caterpillars remain intact after death; however, if AgMNPV is engineered to express the chitinase and cathepsin genes from the baculovirus Choristeneura fumirerana MNPV (CfMNPV), liquefaction occurs (Lima et al, 2013). Carefully choreographed chitinase and cathepsin expression and activity during virus replication are crucial for the collaborative work of these enzymes.…”