Comparative Pathogenesis of Generalist AcMNPV and Specific RanuNPV in Larvae of Rachiplusia nu (Lepidoptera: Noctuidae) Following Single and Mixed Inoculations

2021 ◽  
Author(s):  
Cecilia Decker-Franco ◽  
Catalina B Taibo ◽  
Julio A Di Rienzo ◽  
Victoria Alfonso ◽  
Joel D Arneodo
Keyword(s):  
Autographa Californica ◽  
Tissue Tropism ◽  
South American ◽  
Virus Spread ◽  
Time To Death ◽  
Soybean Pest ◽  
Infected Cells ◽  
Biocontrol Potential ◽  
Lepidoptera Noctuidae ◽  
Autographa Californica Multiple Nucleopolyhedrovirus

Abstract The South American soybean pest, Rachiplusia nu (Guenée), is naturally infected by Autographa californica multiple nucleopolyhedrovirus (AcMNPV) and Rachiplusia nu nucleopolyhedrovirus (RanuNPV). We compared their pathogenicity to fourth-instar R. nu larvae, by evaluating time to death and virus spread throughout the tissues in single and mixed infections. Bioassays showed that generalist AcMNPV had a faster speed of kill than specific RanuNPV, while the mixed-virus treatment did not statistically differ from AcMNPV alone. Histopathology evidenced similar tissue tropism for both viruses, but co-inoculation resulted in mostly AcMNPV-infected cells. In sequential inoculations, however, the first virus administered predominated over the second one. Implications on baculovirus interactions and biocontrol potential are discussed.

scholarly journals Identification and Characterization of the Nucleolar Localization Signal of Autographa californica Multiple Nucleopolyhedrovirus LEF5

2019 ◽  
Vol 94 (4) ◽  
Author(s):  
Guoqing Chen ◽  
Qing Yan ◽  
Haoran Wang ◽  
Shufen Chao ◽  
Lijuan Wu ◽  
...  
Keyword(s):  
Autographa Californica ◽  
Nucleolar Localization ◽  
Sf9 Cells ◽  
Multiple Nucleopolyhedrovirus ◽  
Nucleolar Localization Signal ◽  
Viral Progeny ◽  
Localization Signal ◽  
Infected Cells ◽  
Autographa Californica Multiple Nucleopolyhedrovirus ◽  
Late Expression

ABSTRACT Autographa californica multiple nucleopolyhedrovirus (AcMNPV) late expression factor 5 (LEF5) is highly conserved in all sequenced baculovirus genomes and plays an important role in production of infectious viral progeny. In this study, nucleolar localization of AcMNPV LEF5 was characterized. Through transcriptome analysis, we identified two putative nucleolar proteins, Spodoptera frugiperda nucleostemin (SfNS) and fibrillarin (SfFBL), from Sf9 cells. Immunofluorescence analysis demonstrated that SfNS and SfFBL were localized to the nucleolus. AcMNPV infection resulted in reorganization of the nucleoli of infected cells. Colocalization of LEF5 and SfNS showed that AcMNPV LEF5 was localized to the nucleolus in Sf9 cells. Bioinformatic analysis revealed that basic amino acids of LEF5 are enriched at residues 184 to 213 and may contain a nucleolar localization signal (NoLS). Green fluorescent protein (GFP) fused to NoLS of AcMNPV LEF5 localized to the nucleoli of transfected cells. Multiple-point mutation analysis demonstrated that amino acid residues 197 to 204 are important for nucleolar localization of LEF5. To identify whether the NoLS in AcMNPV LEF5 is important for production of viral progeny, a lef5-null AcMNPV bacmid was constructed; several NoLS-mutated LEF5 proteins were reinserted into the lef5-null AcMNPV bacmid with a GFP reporter. The constructs containing point mutations at residues 185 to 189 or 197 to 204 in AcMNPV LEF5 resulted in reduction in production of infectious viral progeny and occlusion body yield in bacmid-transfected cells. Together, these data suggested that AcMNPV LEF5 contains an NoLS, which is important for nucleolar localization of LEF5, progeny production, and occlusion body production. IMPORTANCE Many viruses, including human and plant viruses, target nucleolar functions as part of their infection strategy. However, nucleolar localization for baculovirus proteins has not yet been characterized. In this study, two nucleolar proteins, SfNS and SfFBL, were identified in Sf9 cells. Our results showed that Autographa californica multiple nucleopolyhedrovirus (AcMNPV) infection resulted in redistribution of the nucleoli of infected cells. We demonstrated that AcMNPV late expression factor 5 (LEF5) could localize to the nucleolus and contains a nucleolar localization signal (NoLS), which is important for nucleolar localization of AcMNPV LEF5 and for production of viral progeny and yield of occlusion bodies.

scholarly journals A Conserved Phenylalanine Residue of Autographa Californica Multiple Nucleopolyhedrovirus AC75 Protein Is Required for Occlusion Body Formation

2021 ◽  
Vol 12 ◽  
Author(s):  
Xingang Chen ◽  
Jian Yang ◽  
Xiaoqin Yang ◽  
Chengfeng Lei ◽  
Xiulian Sun ◽  
...  
Keyword(s):  
Virus Production ◽  
Autographa Californica ◽  
Occlusion Body ◽  
Body Formation ◽  
Viral Propagation ◽  
Multiple Nucleopolyhedrovirus ◽  
Infected Cells ◽  
Budded Virus ◽  
Conserved Gene ◽  
Autographa Californica Multiple Nucleopolyhedrovirus

Autographa californica multiple nucleopolyhedrovirus (AcMNPV) orf75 (ac75) is a highly conserved gene that is essential for AcMNPV propagation. However, the key domains or residues of the AC75 protein that play a role in viral propagation have not been identified. In this study, sequence alignment revealed that residues Phe-54 and Gln-81 of AC75 were highly conserved among alphabaculoviruses and betabaculoviurses. Thus, Phe-54 and Gln-81 AC75 mutation bacmids were constructed. We found that Gln-81 was not required for viral propagation, whereas mutating Phe-54 reduced budded virus production by 10-fold and impaired occlusion body formation when compared with that of the wild-type AcMNPV. Electron microscopy observations showed that the Phe-54 mutation affected polyhedrin assembly and also occlusion-derived virus embedding, whereas western blot analysis revealed that mutating Phe-54 reduced the amount of AC75 but did not affect the localization of AC75 in infected cells. A protein stability assay showed that the Phe-54 mutation affected AC75 stability. Taken together, Phe-54 was identified as an important residue of AC75, and ac75 is a pivotal gene in budding virus production and occlusion body formation.

scholarly journals Autographa californica Multiple Nucleopolyhedrovirus orf13 is Required for Efficient Nuclear Egress of Nucleocapsids

2020 ◽  
Author(s):  
Xingang Chen ◽  
Xiaoqin Yang ◽  
Chengfeng Lei ◽  
Fujun Qin ◽  
Jia Hu ◽  
...  
Keyword(s):  
Autographa Californica ◽  
Wild Type Virus ◽  
Nuclear Egress ◽  
Multiple Nucleopolyhedrovirus ◽  
Localization Signal ◽  
Replication Gene ◽  
Infected Cells ◽  
Nuclear Localization Signal Motif ◽  
Conserved Gene ◽  
Autographa Californica Multiple Nucleopolyhedrovirus

ABSTRACTAutographa californica multiple nucleopolyhedrovirus (AcMNPV) orf13 (ac13) is a conserved gene in all sequenced alphabaculoviruses. However, its function in the viral life cycle remains unknown. In this study we found that ac13 was a late gene and that the encoded protein, bearing a putative nuclear localization signal motif in the DUF3627 domain, colocalized with the nuclear membrane. Deletion of ac13 did not affect viral DNA replication, gene transcription, nucleocapsid assembly or occlusion body (OB) formation, but reduced virion budding from infected cells by approximately 400-fold compared with the wild-type virus. Deletion of ac13 substantially impaired the egress of nucleocapsids from the nucleus to the cytoplasm, while the number of occlusion-derived viruses embedded within OBs was unaffected. Taken together, our results indicated that ac13 was required for efficient nuclear egress of nucleocapsids during virion budding, but was dispensable for OB formation.IMPORTANCEEgress of baculovirus nucleocapsids from the nucleus is an essential process for morphogenesis of mature budded viruses, which is required to spread infection within susceptible cells and tissues. Although many viral and host proteins are required for nucleocapsid egress, the specific mechanisms underlying this process in baculoviruses remain somewhat enigmatic. In the present study, we found that the ac13 gene, in addition to ac11, ac51, ac66, ac75, ac78, gp41, ac93, p48, exon0 and ac142, was required for efficient nuclear egress of nucleocapsids. Our results contribute to a better understanding of nucleocapsid egress in baculoviruses.

scholarly journals Nuclear localization of actin requires AC102 in Autographa californica multiple nucleopolyhedrovirus-infected cells

2012 ◽  
Vol 93 (8) ◽  
pp. 1795-1803 ◽  
Author(s):  
Kamal M. Gandhi ◽  
Taro Ohkawa ◽  
Matthew D. Welch ◽  
Loy E. Volkman
Keyword(s):  
Virus Production ◽  
Autographa Californica ◽  
Current Evidence ◽  
Progeny Virus ◽  
Wild Type ◽  
Multiple Nucleopolyhedrovirus ◽  
Infected Cells ◽  
Budded Virus ◽  
Autographa Californica Multiple Nucleopolyhedrovirus ◽  
Type Infection

Autographa californica multiple nucleopolyhedrovirus requires nuclear actin for progeny virus production and thereby encodes viral products that ensure actin’s translocation to and retention within the nucleus. Current evidence suggests that the ie0–ie1 gene complex along with five nuclear localization of actin (NLA) genes are sufficient for NLA in transient transfection experiments. Here we report that, during infection, only one of the five NLA genes, Ac102, was essential for NLA, and that AC102 had at least one other activity critical for budded virus (BV) production. Viral deletion mutants in the other four NLA genes were viable, with only two having replication phenotypes different from that of the wild type. Infection with AcΔpe38 revealed a delay in both BV production and NLA. Infection with AcΔ152 revealed a delay in BV production, but no corresponding delay in NLA. Infection with either AcΔpe38 or AcΔ152 resulted in slightly reduced BV titres. Deletion of Ac004 or he65 had no impact on actin translocation kinetics, timing of BV production or BV titres. These results implicate AC102 as a key player in baculovirus manipulation of actin.

scholarly journals The Autographa californica Multiple Nucleopolyhedrovirusac51Gene Is Required for Efficient Nuclear Egress of Nucleocapsids and Is Essential forIn VivoVirulence

2018 ◽  
Vol 93 (3) ◽  
Author(s):  
Jianxiang Qiu ◽  
Zhimin Tang ◽  
Yi Cai ◽  
Wenbi Wu ◽  
Meijin Yuan ◽  
...  
Keyword(s):  
Nucleocapsid Protein ◽  
Viral Gene Expression ◽  
Autographa Californica ◽  
Viral Gene ◽  
Wild Type ◽  
Anterograde Transport ◽  
Nuclear Egress ◽  
Infected Cells ◽  
Autographa Californica Multiple Nucleopolyhedrovirus

ABSTRACTAlphabaculoviruses are lepidopteran-specific nucleopolyhedroviruses that replicate within the nucleus; however, the anterograde transport of the nucleocapsids of these viruses, which is an obligatory step for progeny virion production, is not well understood. In the present study, a uniqueAlphabaculovirusgene with unknown function, namely, the Autographa californica multiple nucleopolyhedrovirus (AcMNPV)ac51gene, was found to be required for efficient nuclear egress of AcMNPV nucleocapsids. Our results indicate thatac51is a late gene, and Ac51 protein was detectable from 24 to 72 h postinfection using an antibody raised against Ac51. Ac51 is distributed in both the cytoplasm and nuclei of infected cells. Uponac51deletion, budded virion (BV) production by 96 h posttransfection was reduced by approximately 1,000-fold compared with that of wild-type AcMNPV. Neither viral DNA synthesis nor viral gene expression was affected. Ac51 was demonstrated to be a nucleocapsid protein of BVs, andac51deletion did not interrupt nucleocapsid assembly and occlusion-derived virion (ODV) formation. However, BV production in the supernatants of transfected cells during a viral life cycle was substantially decreased whenac51was deleted. Further analysis showed that, compared with wild-type AcMNPV,ac51deletion decreased nucleocapsid egress, while the numbers of nucleocapsids in the nuclei were comparable. Deletion ofac51also eliminated the virulence of AcMNPVin vivo. Taken together, our results support the conclusion thatac51plays an important role in the nuclear egress of nucleocapsids during BV formation and is essential for thein vivovirulence of AcMNPV.

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