scholarly journals Methyl-Beta-Cyclodextrin-Induced Macropinocytosis Results in Increased Infection of Sf21 Cells by Bombyx Mori Nucleopolyhedrovirus

Viruses ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 937 ◽  
Author(s):  
Huang ◽  
Li ◽  
Fan ◽  
liu ◽  
Boadi ◽  
...  
Keyword(s):  
Bombyx Mori ◽  
Amino Acid Sequence Identity ◽  
Autographa Californica ◽  
Host Cells ◽  
Abortive Infection ◽  
Bombyx Mori Nucleopolyhedrovirus ◽  
Membrane Ruffling ◽  
Beta Cyclodextrin ◽  
Autographa Californica Multiple Nucleopolyhedrovirus ◽  
Entry Mechanism

Bombyx mori nucleopolyhedrovirus (BmNPV) is closely related to Autographa californica multiple nucleopolyhedrovirus (AcMNPV) with over ~93% amino acid sequence identity. However, their host ranges are essentially nonoverlapping. The mechanism of BmNPV entry into host cells is completely different from that of AcMNPV, and whether the entry mechanism difference relates to the host range remains unclear. BmNPV produces an abortive infection in nonhost cells due to virion nuclear transportation failure. Here, we performed a detailed study by increasing BmNPV infection in Sf21 cells with the aid of methyl-beta-cyclodextrin (MβCD). We found that low-concentration MβCD incubation efficiently activates membrane ruffling in Sf21 cells, which mediates the increase in BmNPV infection. Interestingly, MβCD incubation after virion internalization also increases the infection, which suggests that macropinocytosis is involved in BmNPV infection in Sf21 cells after virion internalization. Further study revealed that clathrin-mediated endocytosis (CME) is employed by BmNPV to facilitate entry into Sf21 cells, and chlorpromazine application abolishes BmNPV infection in cells incubated both with and without MβCD. Based on these studies, we show that BmNPV enters Sf21 cells via CME and that parallel induction of macropinocytosis facilitates BmNPV infection in Sf21 cells. This study reveals the mechanism of BmNPV entry into Sf21 cells and provides clues for improving BmNPV infections in nonpermissive cells.

scholarly journals Transport via Macropinocytic Vesicles Is Crucial for Productive Infection with Bombyx Mori Nucleopolyhedrovirus

Viruses ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 668 ◽  
Author(s):  
Jinshan Huang ◽  
Chenya Li ◽  
Xudong Tang ◽  
Lin Liu ◽  
Wenbin Nan ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Bombyx Mori ◽  
Low Ph ◽  
Host Cells ◽  
Productive Infection ◽  
Bombyx Mori Nucleopolyhedrovirus ◽  
Viral Pathogen ◽  
Essential Condition ◽  
Fluid Uptake ◽  
Entry Mechanism

Bombyx mori nucleopolyhedrovirus (BmNPV) is a serious viral pathogen in the sericulture industry and enters host cells via macropinocytic endocytosis; however, the current understanding of the BmNPV entry mechanism remains limited. To confirm whether direct membrane fusion (DMF) results in productive BmNPV infection, DMF infectivity induced by low pH during BmNPV infection was investigated, and the infectious viral particle was traced using an eGFP-labeled virion. We found that BmNPV infection efficiently induced fluid uptake, which allowed BmNPV to bypass the cell membrane barrier via macropinocytosis. However, DMF induced by a low pH abolished the infection. While low pH is an essential condition for membrane fusion triggering, it is not sufficient for productive BmNPV infection, and DMF results in failure to transport the nucleocapsid into the nucleus. These results indicate that transport via macropinocytic vesicles facilitates BmNPV entry into the nucleus and contribute to our understanding of the BmNPV entry mechanism.

scholarly journals Dynamic Interactions between Bombyx mori Nucleopolyhedrovirus and Its Host Cells Revealed by Transcriptome Analysis

2012 ◽  
Vol 86 (13) ◽  
pp. 7345-7359 ◽  
Author(s):  
J. Xue ◽  
N. Qiao ◽  
W. Zhang ◽  
R.-L. Cheng ◽  
X.-Q. Zhang ◽  
...  
Keyword(s):  
Bombyx Mori ◽  
Transcriptome Analysis ◽  
Host Cells ◽  
Bombyx Mori Nucleopolyhedrovirus ◽  
Dynamic Interactions

scholarly journals Ac102 Participates in Nuclear Actin Polymerization by Modulating BV/ODV-C42 Ubiquitination during Autographa californica Multiple Nucleopolyhedrovirus Infection

2018 ◽  
Vol 92 (12) ◽  
Author(s):  
Yongli Zhang ◽  
Xue Hu ◽  
Jingfang Mu ◽  
Yangyang Hu ◽  
Yuan Zhou ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Proteasomal Degradation ◽  
Autographa Californica ◽  
Host Cells ◽  
Nuclear Accumulation ◽  
Nuclear Actin ◽  
Regulatory Cascade ◽  
Multiple Nucleopolyhedrovirus ◽  
Nucleation Promoting Factor ◽  
Autographa Californica Multiple Nucleopolyhedrovirus

ABSTRACTAs a virus-encoded actin nucleation promoting factor (NPF), P78/83 induces actin polymerization to assist in Autographa californica multiple nucleopolyhedrovirus (AcMNPV) propagation. According to our previous study, although P78/83 actively undergoes ubiquitin-independent proteasomal degradation, AcMNPV encodes budded virus/occlusion derived virus (BV/ODV)-C42 (C42), which allows P78/83 to function as a stable NPF by inhibiting its degradation during viral infection. However, whether there are other viral proteins involved in regulating P78/83-induced actin polymerization has yet to be determined. In this study, we found that Ac102, an essential viral gene product previously reported to play a key role in mediating the nuclear accumulation of actin during AcMNPV infection, is a novel regulator of P78/83-induced actin polymerization. By characterizing anac102knockout bacmid, we demonstrated that Ac102 participates in regulating nuclear actin polymerization as well as the morphogenesis and distribution of capsid structures in the nucleus. These regulatory effects are heavily dependent on an interaction between Ac102 and C42. Further investigation revealed that Ac102 binds to C42 to suppress K48-linked ubiquitination of C42, which decreases C42 proteasomal degradation and consequently allows P78/83 to function as a stable NPF to induce actin polymerization. Thus, Ac102 and C42 form a regulatory cascade to control viral NPF activity, representing a sophisticated mechanism for AcMNPV to orchestrate actin polymerization in both a ubiquitin-dependent and ubiquitin-independent manner.IMPORTANCEActin is one of the most functionally important proteins in eukaryotic cells. Morphologically, actin can be found in two forms: a monomeric form called globular actin (G-actin) and a polymeric form called filamentous actin (F-actin). G-actin can polymerize to form F-actin, and nucleation promoting factor (NPF) is the initiator of this process. Many viral pathogens harness the host actin polymerization machinery to assist in virus propagation. Autographa californica multiple nucleopolyhedrovirus (AcMNPV) induces actin polymerization in host cells. P78/83, a viral NPF, is responsible for this process. Previously, we identified that BV/ODV-C42 (C42) binds to P78/83 and protects it from degradation. In this report, we determined that another viral protein, Ac102, is involved in modulating C42 ubiquitination and, consequently, ensures P78/83 activity as an NPF to initiate actin polymerization. This regulatory cascade represents a novel mechanism by which a virus can harness the cellular actin cytoskeleton to assist in viral propagation.

scholarly journals Autographa Californica Multiple Nucleopolyhedrovirus Enters Host Cells via Clathrin-Mediated Endocytosis and Direct Fusion with the Plasma Membrane

Viruses ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 632 ◽  
Author(s):  
Fujun Qin ◽  
Congrui Xu ◽  
Chengfeng Lei ◽  
Jia Hu ◽  
Xiulian Sun
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Autographa Californica ◽  
Host Cells ◽  
Quantitative Electron Microscopy ◽  
Virus Particles ◽  
Multiple Nucleopolyhedrovirus ◽  
Single Virus Tracking ◽  
Autographa Californica Multiple Nucleopolyhedrovirus ◽  
Direct Fusion

The cell entry mechanism of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is not fully understood. Previous studies showed that AcMNPV entered host cells primarily through clathrin-mediated endocytosis, and could efficiently infect cells via fusion with the plasma membrane after a low-pH trigger. However, whether AcMNPV enters cells via these two pathways simultaneously, and the exact manner in which AcMNPV particles are internalized into cells remains unclear. In this study, using single-virus tracking, we observed that AcMNPV particles were first captured by pre-existing clathrin-coated pits (CCP), and were then delivered to early endosomes. Population-based analysis of single-virus tracking and quantitative electron microscopy demonstrated that the majority of particles were captured by CCPs and internalized via invagination. In contrast, a minority of virus particles were not delivered to CCPs, and were internalized through direct fusion with the plasma membrane without invagination. Quantitative electron microscopy also showed that, while inhibition of CCP assembly significantly impaired viral internalization, inhibition of endosomal acidification blocked virus particles out of vesicles. Collectively, these findings demonstrated that approximately 90% of AcMNPV particles entered cells through clathrin-mediated endocytosis and 10% entered via direct fusion with the plasma membrane. This study will lead toward a better understanding of AcMNPV infection.

scholarly journals Degradation of rRNA in BM-N cells from the silkworm Bombyx mori during abortive infection with heterologous nucleopolyhedroviruses

2013 ◽  
Vol 94 (9) ◽  
pp. 2102-2111 ◽  
Author(s):  
Rina Hamajima ◽  
Yuya Ito ◽  
Haruka Ichikawa ◽  
Hiroshi Mitsutake ◽  
Jun Kobayashi ◽  
...  
Keyword(s):  
Bombyx Mori ◽  
Spodoptera Exigua ◽  
Autographa Californica ◽  
Cosmid Library ◽  
S2 Cells ◽  
Abortive Infection ◽  
Hyphantria Cunea ◽  
Transient Expression Assay ◽  
Rrna Degradation ◽  
Silkworm Bombyx Mori

Cell lines derived from the silkworm, Bombyx mori, are only permissive for B. mori nucleopolyhedrovirus (NPV), with other NPVs generally resulting in abortive infection. Here, we demonstrate that rRNA of B. mori BM-N cells undergoes rapid degradation through site-specific cleavage upon infection with NPVs from Autographa californica (AcMNPV), Hyphantria cunea (HycuMNPV), Spodoptera exigua (SeMNPV) and Spodoptera litura (SpltMNPV). No significant decreases in cellular RNA were observed in Ld652Y, Se301, Sf9, SpIm and S2 cells infected with AcMNPV or HycuMNPV, indicating the response is unique to BM-N cells. A transient expression assay using a cosmid library of the HycuMNPV genome demonstrated that HycuMNPV P143 is responsible for rRNA degradation, which was also detected in BM-N cells transfected with plasmids expressing the P143 proteins from AcMNPV, SeMNPV and SpltMNPV. These results indicate that B. mori evolved to acquire a unique antiviral immune mechanism that is activated by P143 proteins from heterologous NPVs.

Systematic analysis of nuclear localization of Autographa californica multiple nucleopolyhedrovirus proteins

2021 ◽  
Author(s):  
Lihong He ◽  
Wei Shao ◽  
Jiang Li ◽  
Fei Deng ◽  
Hualin Wang ◽  
...  
Keyword(s):  
Virus Infection ◽  
Transient Expression ◽  
Nuclear Localization ◽  
Protein Localization ◽  
Viral Proteins ◽  
Autographa Californica ◽  
Host Cells ◽  
Genome Replication ◽  
Multiple Nucleopolyhedrovirus ◽  
Autographa Californica Multiple Nucleopolyhedrovirus

Baculoviruses are large DNA viruses that replicate within the nucleus of infected host cells. Therefore, many viral proteins must gain access to the nucleus for efficient viral genome replication, gene transcription and virion assembly. To date, the global protein localization pattern of baculoviral proteins is unknown. In this study, we systematically analysed the nuclear localization of 154 ORFs encoded by the prototypic baculovirus, Autographa californica multiple nucleopolyhedrovirus (AcMNPV), either during transient expression or with super-infection of the virus. By transient expression of vectors containing egfp-fused ORFs, we found that in the absence of virus infection, 25 viral proteins were localized in the nucleus. Most of these, which we called ‘auto-nuclear localization’ proteins, are related to virus replication, transcription or virion structure, and 20 of them contain predicted classical nuclear localization signal. Upon virus infection, 11 proteins, which originally localized in the cytoplasm or both cytoplasm and nucleus in the transfection assays, were completely translocated into the nucleus, suggesting that their nuclear import is facilitated by other viral or host proteins. Further co-transfection experiments identified that four of the 11 proteins, including P143, P33, AC73 and AC114, were imported into the nucleus with the assistance of the auto-nuclear localization proteins LEF-3 (for P143), TLP (for P33) and VP80 (for both AC73 and AC114). This study presents the first global nuclear localization profile of AcMNPV proteins and provides useful information for further elucidation of the mechanisms of baculovirus nuclear entry and gene functions.

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