Genome Analysis of an Alphabaculovirus Isolated from the Larch Looper, Erannis ankeraria

Long Liu,Zhilin Zhang,Chenglin Liu,Liangjian Qu,Dun Wang

doi:10.3390/v14010034

Abstract

The larch looper, Erannis ankeraria Staudinger (Lepidoptera: Geometridae), is one of the major insect pests of larch forests, widely distributed from southeastern Europe to East Asia. A naturally occurring baculovirus, Erannis ankeraria nucleopolyhedrovirus (EranNPV), was isolated from E. ankeraria larvae. This virus was characterized by electron microscopy and by sequencing the whole viral genome. The occlusion bodies (OBs) of EranNPV exhibited irregular polyhedral shapes containing multiple enveloped rod-shaped virions with a single nucleocapsid per virion. The EranNPV genome was 125,247 bp in length with a nucleotide distribution of 34.9% G+C. A total of 131 hypothetical open reading frames (ORFs) were identified, including the 38 baculovirus core genes and five multi-copy genes. Five homologous regions (hrs) were found in the EranNPV genome. Phylogeny and pairwise kimura 2-parameter analysis indicated that EranNPV was a novel group II alphabaculovirus and was most closely related to Apocheima cinerarium NPV (ApciNPV). Field trials showed that EranNPV was effective in controlling E. ankeraria in larch forests. The above results will be relevant to the functional research on EranNPV and promote the use of this virus as a biocontrol agent.

Highlights

Baculoviruses are pathogenic viruses that mainly infect insects of orders Lepidoptera, Diptera, and Hymenoptera
Field trials showed that Erannis ankeraria nucleopolyhedrovirus (EranNPV) was effective in controlling E. ankeraria in larch forests
occlusion-derived virus (ODV) are embedded in proteinaceous occlusion bodies (OBs), which provide the virus with physical protection in the environment

Summary

Introduction

Baculoviruses are pathogenic viruses that mainly infect insects of orders Lepidoptera, Diptera, and Hymenoptera. Baculoviruses typically infect only one or a few related insect species and are successfully employed as environmentally safe biopesticides for pest control [1–3]. One virion phenotype is called the budded virus (BV), which is responsible for spreading infection systemically from cell to cell throughout the host, and another one is referred to as the occlusion-derived virus (ODV) transmitting infection orally from insect to insect [7]. The family Baculoviridae is composed of four genera: Alphabaculovirus (NPVs that infect the insect order Lepidoptera), Betabaculovirus (GVs that infect the insect order Lepidoptera), Gammabaculovirus (NPVs that infect the insect order Hymenoptera), and Deltabaculovirus (NPVs that infect the insect order Diptera) [9]

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Discussion

Conclusion