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24 pages, 7684 KiB

Open AccessArticle

PIWI Proteins Play an Antiviral Role in Lepidopteran Cell Lines

by Dulce Santos, Thomas-Wolf Verdonckt, Lina Mingels, Stijn Van den Brande, Bart Geens, Filip Van Nieuwerburgh, Anna Kolliopoulou, Luc Swevers, Niels Wynant and Jozef Vanden Broeck

Viruses 2022, 14(7), 1442; https://doi.org/10.3390/v14071442 - 30 Jun 2022

Cited by 12 | Viewed by 2965

Abstract

Insect antiviral immunity primarily relies on RNAi mechanisms. While a key role of small interfering (si)RNAs and AGO proteins has been well established in this regard, the situation for PIWI proteins and PIWI-interacting (pi)RNAs is not as clear. In the present study, we investigate whether PIWI proteins and viral piRNAs are involved in the immunity against single-stranded RNA viruses in lepidopteran cells, where two PIWIs are identified (Siwi and Ago3). Via loss- and gain-of-function studies in Bombyx mori BmN4 cells and in Trichoplusia ni High Five cells, we demonstrated an antiviral role of Siwi and Ago3. However, small RNA analysis suggests that viral piRNAs can be absent in these lepidopteran cells. Together with the current literature, our results support a functional diversification of PIWI proteins in insects. Full article

(This article belongs to the Section Invertebrate Viruses)

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17 pages, 5561 KiB

Open AccessArticle

Metabolomic Analysis of Cricket paralysis virus Infection in Drosophila S2 Cells Reveals Divergent Effects on Central Carbon Metabolism as Compared with Silkworm Bm5 Cells

by Luo-Luo Wang, Luc Swevers, Lieven Van Meulebroek, Ivan Meeus, Lynn Vanhaecke and Guy Smagghe

Viruses 2020, 12(4), 393; https://doi.org/10.3390/v12040393 - 1 Apr 2020

Cited by 9 | Viewed by 3305

Abstract

High-throughput approaches have opened new opportunities for understanding biological processes such as persistent virus infections, which are widespread. However, the potential of persistent infections to develop towards pathogenesis remains to be investigated, particularly with respect to the role of host metabolism. To explore the interactions between cellular metabolism and persistent/pathogenic virus infection, we performed untargeted and targeted metabolomic analysis to examine the effects of Cricket paralysis virus (CrPV, Dicistroviridae) in persistently infected silkworm Bm5 cells and acutely infected Drosophila S2 cells. Our previous study (Viruses 2019, 11, 861) established that both glucose and glutamine levels significantly increased during the persistent period of CrPV infection of Bm5 cells, while they decreased steeply during the pathogenic stages. Strikingly, in this study, an almost opposite pattern in change of metabolites was observed during different stages of acute infection of S2 cells. More specifically, a significant decrease in amino acids and carbohydrates was observed prior to pathogenesis, while their abundance significantly increased again during pathogenesis. Our study illustrates the occurrence of diametrically opposite changes in central carbon mechanisms during CrPV infection of S2 and Bm5 cells that is possibly related to the type of infection (acute or persistent) that is triggered by the virus. Full article

(This article belongs to the Section Invertebrate Viruses)

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18 pages, 3371 KiB

Open AccessArticle

A Metabolomics Approach to Unravel Cricket Paralysis Virus Infection in Silkworm Bm5 Cells

by Luo-Luo Wang, Luc Swevers, Caroline Rombouts, Ivan Meeus, Lieven Van Meulebroek, Lynn Vanhaecke and Guy Smagghe

Viruses 2019, 11(9), 861; https://doi.org/10.3390/v11090861 - 16 Sep 2019

Cited by 17 | Viewed by 4916

Abstract

How a host metabolism responds to infection with insect viruses and how it relates to pathogenesis, is little investigated. Our previous study observed that Cricket paralysis virus (CrPV, Dicistroviridae) causes short term persistence in silkworm Bm5 cells before proceeding to acute infection. In this study, a metabolomics approach based on high resolution mass spectrometry was applied to investigate how a host metabolism is altered during the course of CrPV infection in Bm5 cells and which changes are characteristic for the transition from persistence to pathogenicity. We observed that CrPV infection led to significant and stage-specific metabolic changes in Bm5 cells. Differential metabolites abundance and pathway analysis further identified specific metabolic features at different stages in the viral life cycle. Notably, both glucose and glutamine levels significantly increased during CrPV persistent infection followed by a steep decrease during the pathogenic stages, suggesting that the central carbon metabolism was significantly modified during CrPV infection in Bm5 cells. In addition, dynamic changes in levels of polyamines were detected. Taken together, this study characterized for the first time the metabolic dynamics of CrPV infection in insect cells, proposing a central role for the regulation of both amino acid and carbohydrate metabolism during the period of persistent infection of CrPV in Bm5 cells. Full article

(This article belongs to the Section Invertebrate Viruses)

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17 pages, 1323 KiB

Open AccessArticle

Israeli Acute Paralysis Virus Infection Leads to an Enhanced RNA Interference Response and Not Its Suppression in the Bumblebee Bombus terrestris

by Kaat Cappelle, Guy Smagghe, Maarten Dhaenens and Ivan Meeus

Viruses 2016, 8(12), 334; https://doi.org/10.3390/v8120334 - 19 Dec 2016

Cited by 16 | Viewed by 5867

Abstract

RNA interference (RNAi) is the primary antiviral defense system in insects and its importance for pollinator health is indisputable. In this work, we examined the effect of Israeli acute paralysis virus (IAPV) infection on the RNAi process in the bumblebee, Bombus terrestris, and whether the presence of possible functional viral suppressors could alter the potency of the host’s immune response. For this, a two-fold approach was used. Through a functional RNAi assay, we observed an enhancement of the RNAi system after IAPV infection instead of its suppression, despite only minimal upregulation of the genes involved in RNAi. Besides, the presence of the proposed suppressor 1A and the predicted OrfX protein in IAPV could not be confirmed using high definition mass spectrometry. In parallel, when bumblebees were infected with cricket paralysis virus (CrPV), known to encode a suppressor of RNAi, no increase in RNAi efficiency was seen. For both viruses, pre-infection with the one virus lead to a decreased replication of the other virus, indicating a major effect of competition. These results are compelling in the context of Dicistroviridae in multi-virus/multi-host networks as the effect of a viral infection on the RNAi machinery may influence subsequent virus infections. Full article

(This article belongs to the Section Invertebrate Viruses)

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20 pages, 2850 KiB

Open AccessArticle

Temporal Regulation of Distinct Internal Ribosome Entry Sites of the Dicistroviridae Cricket Paralysis Virus

by Anthony Khong, Jennifer M. Bonderoff, Ruth V. Spriggs, Erik Tammpere, Craig H. Kerr, Thomas J. Jackson, Anne E. Willis and Eric Jan

Viruses 2016, 8(1), 25; https://doi.org/10.3390/v8010025 - 19 Jan 2016

Cited by 25 | Viewed by 7893

Abstract

Internal ribosome entry is a key mechanism for viral protein synthesis in a subset of RNA viruses. Cricket paralysis virus (CrPV), a member of Dicistroviridae, has a positive-sense single strand RNA genome that contains two internal ribosome entry sites (IRES), a 5′untranslated region (5′UTR) and intergenic region (IGR) IRES, that direct translation of open reading frames (ORF) encoding the viral non-structural and structural proteins, respectively. The regulation of and the significance of the CrPV IRESs during infection are not fully understood. In this study, using a series of biochemical assays including radioactive-pulse labelling, reporter RNA assays and ribosome profiling, we demonstrate that while 5′UTR IRES translational activity is constant throughout infection, IGR IRES translation is delayed and then stimulated two to three hours post infection. The delay in IGR IRES translation is not affected by inhibiting global translation prematurely via treatment with Pateamine A. Using a CrPV replicon that uncouples viral translation and replication, we show that the increase in IGR IRES translation is dependent on expression of non-structural proteins and is greatly stimulated when replication is active. Temporal regulation by distinct IRESs within the CrPV genome is an effective viral strategy to ensure optimal timing and expression of viral proteins to facilitate infection. Full article

(This article belongs to the Special Issue Viral Subversion of Stress Responses and Translational Control)

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