Hairpin transfer-independent Parvovirus DNA Replication Produces Infectious Virus

2021 ◽  
Author(s):  
Weiran Shen ◽  
Zekun Wang ◽  
Kang Ning ◽  
Fang Cheng ◽  
John F. Engelhardt ◽  
...  
Keyword(s):  
Dna Replication ◽  
Hek293 Cells ◽  
Progeny Virus ◽  
Human Bocavirus ◽  
Viral Dna ◽  
Airway Epithelia ◽  
Viral Dna Replication ◽  
Human Airway ◽  
The Right ◽  
Human Airway Epithelia

Parvoviruses package a linear single-stranded DNA genome with hairpin structures at both ends. It has been thought that terminal hairpin sequences are indispensable for viral DNA replication. Here, we provide evidence that the hairpin-deleted duplex genomes of human bocavirus 1 (HBoV1) replicate in human embryonic kidney (HEK) 293 cells. We propose an alternative model for HBoV1 DNA replication in which the leading strand can initiate strand-displacement without “hairpin-transfer.” The transfection of the HBoV1 duplex genomes that retain a minimal replication origin at the right-end ( OriR ), but with extensive deletions in the right-end hairpin (REH), generated viruses in HEK293 cells at a level 10-20 times lower than the wild-type (WT) duplex genome. Importantly, these viruses that have a genome with various deletions after the OriR , but not the one retaining only the OriR , replicated in polarized human airway epithelia. We discovered that the 18-nt sequence (nt 5,403-5,420) beyond the OriR was sufficient to confer virus replication in polarized human airway epithelia, although its progeny virus production was ∼5 times lower than that of the WT virus. Thus, our study demonstrates that hairpin transfer-independent productive parvovirus DNA replication can occur. Importance Hairpin transfer-independent parvovirus replication was modeled with human bocavirus 1 (HBoV1) duplex genomes whose 5’ hairpin structure was ablated by various deletions. In HEK293 cells, these duplex viral genomes with ablated 5’/hairpin sequence replicated efficiently and generated viruses that productively infected polarized human airway epithelium. Thus, for the first time, we reveal a previously unknown phenomenon that the productive parvovirus DNA replication does not depend on the hairpin sequence at REH to initiate “rolling hairpin” DNA replication. Notably, the intermediates of viral DNA replication, as revealed two-dimensional electrophoresis, from transfections of hairpin sequence-deleted duplex genome and full-length genome in HEK293 cells, as well as from virus infection of polarized human airway epithelia are similar. Thus, the establishment of the hairpin transfer-independent parvoviral DNA replication deepens our understanding in viral DNA replication and may have implications in development of parvovirus-based viral vectors with alternative properties.

scholarly journals Analysis ofcisandtransRequirements for DNA Replication at the Right-End Hairpin of the Human Bocavirus 1 Genome

2016 ◽  
Vol 90 (17) ◽  
pp. 7761-7777 ◽  
Author(s):  
Weiran Shen ◽  
Xuefeng Deng ◽  
Wei Zou ◽  
John F. Engelhardt ◽  
Ziying Yan ◽  
...  
Keyword(s):  
Dna Replication ◽  
Replication Origin ◽  
Respiratory Tract Infections ◽  
Nonstructural Protein ◽  
Hek293 Cells ◽  
Human Bocavirus ◽  
Viral Dna ◽  
Viral Dna Replication ◽  
The Right ◽  
Tract Infections

ABSTRACTParvoviruses are single-stranded DNA viruses that use the palindromic structures at the ends of the viral genome for their replication. The mechanism of parvovirus replication has been studied mostly in the dependoparvovirus adeno-associated virus 2 (AAV2) and the protoparvovirus minute virus of mice (MVM). Here, we used human bocavirus 1 (HBoV1) to understand the replication mechanism of bocaparvovirus. HBoV1 is pathogenic to humans, causing acute respiratory tract infections, especially in young children under 2 years old. By using the duplex replicative form of the HBoV1 genome in human embryonic kidney 293 (HEK293) cells, we identified the HBoV1 minimal replication origin at the right-end hairpin (OriR). Mutagenesis analyses confirmed the putative NS1 binding and nicking sites within the OriR. Of note, unlike the large nonstructural protein (Rep78/68 or NS1) of other parvoviruses, HBoV1 NS1 did not specifically bind OriRin vitro, indicating that other viral and cellular components or the oligomerization of NS1 is required for NS1 binding to the OriR.In vivostudies demonstrated that residues responsible for NS1 binding and nicking are within the origin-binding domain. Further analysis identified that the small nonstructural protein NP1 is required for HBoV1 DNA replication at OriR. NP1 and other viral nonstructural proteins (NS1 to NS4) colocalized within the viral DNA replication centers in both OriR-transfected cells and virus-infected cells, highlighting a direct involvement of NP1 in viral DNA replication at OriR. Overall, our study revealed the characteristics of HBoV1 DNA replication at OriR, suggesting novel characteristics of autonomous parvovirus DNA replication.IMPORTANCEHuman bocavirus 1 (HBoV1) causes acute respiratory tract infections in young children. The duplex HBoV1 genome replicates in HEK293 cells and produces progeny virions that are infectious in well-differentiated airway epithelial cells. A recombinant AAV2 vector pseudotyped with an HBoV1 capsid has been developed to efficiently deliver the cystic fibrosis transmembrane conductance regulator gene to human airway epithelia. Here, we identified bothcis-acting elements andtrans-acting proteins that are required for HBoV1 DNA replication at the right-end hairpin in HEK293 cells. We localized the minimal replication origin, which contains both NS1 nicking and binding sites, to a 46-nucleotide sequence in the right-end hairpin. The identification of these essential elements of HBoV1 DNA replication acting both incisand intranswill provide guidance to develop antiviral strategies targeting viral DNA replication at the right-end hairpin and to design next-generation recombinant HBoV1 vectors, a promising tool for gene therapy of lung diseases.

scholarly journals The large nonstructural protein (NS1) of the human bocavirus 1 (HBoV1) directly interacts with Ku70, which plays an important role in virus replication in human airway epithelia

2021 ◽  
Author(s):  
Liting Shao ◽  
Kang Ning ◽  
Jianke Wang ◽  
Fang Cheng ◽  
Shengqi Wang ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Dna Damage Response ◽  
Nonstructural Protein ◽  
Direct Interaction ◽  
Human Bocavirus ◽  
Viral Dna ◽  
Viral Dna Replication ◽  
Human Airway ◽  
Damage Response

Human bocavirus 1 (HBoV1), an autonomous human parvovirus, causes acute respiratory tract infections in young children. HBoV1 infects well-differentiated (polarized) human airway epithelium cultured at an air-liquid interface (HAE-ALI). HBoV1 expresses a large nonstructural protein, NS1, that is essential for viral DNA replication. HBoV1 infection of polarized human airway epithelial cells induces a DNA damage response (DDR) that is critical to viral DNA replication involving DNA repair with error-free Y-family DNA polymerases. HBoV1 NS1 or the isoform NS1-70 per se induces a DDR. In this study, using the second-generation proximity-dependent biotin identification (BioID2) approach, we identified that Ku70 is associated with the NS1-BioID2 pulldown complex through a direct interaction with NS1. Bio-layer Interferometry (BLI) assay determined a high binding affinity of the NS1 with Ku70, which has an equilibrium dissociation constant (K D ) value of 0.16 μM and processes the strongest interaction at the C-terminal domain. The association of Ku70 with NS1 was also revealed during HBoV1 infection of HAE-ALI. Knockdown of Ku70 and overexpression of the C-terminal domain of Ku70 significantly decreased HBoV1 replication in HAE-ALI. Thus, our study provides for the first time a direct interaction of a parvovirus large nonstructural protein NS1 with Ku70. IMPORTANCE Parvovirus infection induces a DNA damage response (DDR) that plays a pivotal role in viral DNA replication. The DDR includes activation of ATM (Ataxia telangiectasia mutated), ATR (ATM- and RAD3-related), and DNA-PKcs (DNA-dependent protein kinase catalytic subunit). The large nonstructural protein (NS1) often plays a role in the induction of DDR; however, how the DDR is induced during parvovirus infection or simply by the NS1 is not well studied. Activation of DNA-PKcs has been shown as one of the key DDR pathways in DNA replication of HBoV1. We identified that HBoV1 NS1 directly interacts with Ku70, but not Ku80, of the Ku70/Ku80 heterodimer at a high affinity. This interaction is also important for HBoV1 replication in HAE-ALI. We propose that the interaction of the NS1 with Ku70 recruits the Ku70/Ku80 complex to the viral DNA replication center, which activates DNA-PKcs and facilitates viral DNA replication.

scholarly journals Cellular Cleavage and Polyadenylation Specificity Factor 6 (CPSF6) Mediates Nuclear Import of Human Bocavirus 1 NP1 Protein and Modulates Viral Capsid Protein Expression

2019 ◽  
Vol 94 (2) ◽  
Author(s):  
Xiaomei Wang ◽  
Peng Xu ◽  
Fang Cheng ◽  
Yi Li ◽  
Zekun Wang ◽  
...  
Keyword(s):  
Dna Replication ◽  
Capsid Protein ◽  
Nuclear Import ◽  
Nonstructural Protein ◽  
Human Bocavirus ◽  
Viral Dna ◽  
Viral Dna Replication ◽  
Specificity Factor ◽  
Tract Infections

ABSTRACT Human bocavirus 1 (HBoV1), which belongs to the genus Bocaparvovirus of the Parvoviridae family, causes acute respiratory tract infections in young children. In vitro, HBoV1 infects polarized primary human airway epithelium (HAE) cultured at an air-liquid interface (HAE-ALI). HBoV1 encodes a small nonstructural protein, nuclear protein 1 (NP1), that plays an essential role in the maturation of capsid protein (VP)-encoding mRNAs and viral DNA replication. In this study, we determined the broad interactome of NP1 using the proximity-dependent biotin identification (BioID) assay combined with mass spectrometry (MS). We confirmed that two host mRNA processing factors, DEAH-box helicase 15 (DHX15) and cleavage and polyadenylation specificity factor 6 (CPSF6; also known as CFIm68), a subunit of the cleavage factor Im complex (CFIm), interact with HBoV1 NP1 independently of any DNA or mRNAs. Knockdown of CPSF6 significantly decreased the expression of capsid protein but not that of DHX15. We further demonstrated that NP1 directly interacts with CPSF6 in vitro and colocalizes within the virus replication centers. Importantly, we revealed a novel role of CPSF6 in the nuclear import of NP1, in addition to the critical role of CPSF6 in NP1-facilitated maturation of VP-encoding mRNAs. Thus, our study suggests that CPSF6 interacts with NP1 to escort NP1 imported into the nucleus for its function in the modulation of viral mRNA processing and viral DNA replication. IMPORTANCE Human bocavirus 1 (HBoV1) is one of the significant pathogens causing acute respiratory tract infections in young children worldwide. HBoV1 encodes a small nonstructural protein (NP1) that plays an important role in the maturation of viral mRNAs encoding capsid proteins as well as in viral DNA replication. Here, we identified a critical host factor, CPSF6, that directly interacts with NP1, mediates the nuclear import of NP1, and plays a role in the maturation of capsid protein-encoding mRNAs in the nucleus. The identification of the direct interaction between viral NP1 and host CPSF6 provides new insights into the mechanism by which a viral small nonstructural protein facilitates the multiple regulation of viral gene expression and replication and reveals a novel target for potent antiviral drug development.

scholarly journals Human Bocavirus 1 Is a Novel Helper for Adeno-associated Virus Replication

2017 ◽  
Vol 91 (18) ◽  
Author(s):  
Zekun Wang ◽  
Xuefeng Deng ◽  
Wei Zou ◽  
John F. Engelhardt ◽  
Ziying Yan ◽  
...  
Keyword(s):  
Dna Replication ◽  
Hela Cells ◽  
Helper Virus ◽  
Hek293 Cells ◽  
Human Bocavirus ◽  
Airway Epithelia ◽  
Adeno Associated Virus ◽  
Damage Response ◽  
Helper Function ◽  
Well Differentiated

ABSTRACT Human bocavirus 1 (HBoV1) is an autonomous parvovirus that infects well-differentiated primary human airway epithelia (HAE) in vitro. In human embryonic kidney HEK293 cells, the transfection of a duplex HBoV1 genome initiates viral DNA replication and produces progeny virions that are infectious in HAE. HBoV1 takes advantage of signaling pathways in the DNA damage response for efficient genome amplification in both well-differentiated (nondividing) HAE and dividing HEK293 cells. On the other hand, adeno-associated virus 2 (AAV2) is a helper-dependent dependoparvovirus, and productive AAV2 replication requires coinfection with a helper virus (e.g., adenovirus or herpesvirus) or treatment with genotoxic agents. Here, we report that HBoV1 is a novel helper virus for AAV2 replication. Coinfection by HBoV1 and AAV2 rescued AAV2 replication in HAE cells. The helper function of HBoV1 for AAV2 is not limited to HAE cells but also includes HEK293 and HeLa cells. Importantly, the helper function of HBoV1 for AAV2 relies on neither HBoV1 replication nor the DNA damage response. Following transfection of HEK293 cells, the minimal requirements for the replication of the AAV2 duplex DNA genome and the production of progeny virions included the HBoV1 NP1 and NS4 proteins and a newly identified viral long noncoding RNA (BocaSR). However, following infection of HEK293 and HeLa cells with AAV2 virions, HBoV1 NS2 (but not NS4), NP1, and BocaSR were required for AAV2 DNA replication and progeny virion formation. These new methods for packaging the AAV2 genome may be useful for generating recombinant AAV-packaging cell lines and the directed evolution of AAV capsids. IMPORTANCE We first report that an autonomous parvovirus, HBoV1, helps the replication of a dependoparvovirus, AAV2, in differentiated human airway epithelia. We identified the minimal sets of HBoV1 genes required to facilitate the replication of the AAV2 duplex genome and for AAV2 infection. Notably, together with the expression of the NP1 and BocaSR genes, HBoV1 NS2 is required for the productive infection of HEK293 and HeLa cells by AAV2, whereas NS4 is sufficient for viral DNA replication of an AAV2 duplex genome. The identification of HBoV1 as a helper virus for AAV2 replication has implications for the improvement of recombinant AAV production in HEK293 cells and cell types that do not express the adenovirus E1 gene as well as for the rescue of wild-type AAV genomes from tissues during directed evolution in the absence of wild-type adenovirus. A further understanding of the mechanism underlying HBoV1 helper-dependent AAV2 replication may also provide insights into its functions in HBoV1 replication.

scholarly journals Human Parvovirus Infection of Human Airway Epithelia Induces Pyroptotic Cell Death by Inhibiting Apoptosis

2017 ◽  
Vol 91 (24) ◽  
Author(s):  
Xuefeng Deng ◽  
Wei Zou ◽  
Min Xiong ◽  
Zekun Wang ◽  
John F. Engelhardt ◽  
...  
Keyword(s):  
Cell Death ◽  
Epithelial Cells ◽  
Airway Epithelial Cells ◽  
Human Bocavirus ◽  
Airway Epithelial ◽  
Airway Epithelia ◽  
Human Airway ◽  
Caspase 1 ◽  
Tract Infections ◽  
Human Airway Epithelia

ABSTRACT Human bocavirus 1 (HBoV1) is a human parvovirus that causes acute respiratory tract infections in young children. In this study, we confirmed that, when polarized/well-differentiated human airway epithelia are infected with HBoV1 in vitro, they develop damage characterized by barrier function disruption and cell hypotrophy. Cell death mechanism analyses indicated that the infection induced pyroptotic cell death characterized by caspase-1 activation. Unlike infections with other parvoviruses, HBoV1 infection did not activate the apoptotic or necroptotic cell death pathway. When the NLRP3-ASC-caspase-1 inflammasome-induced pathway was inhibited by short hairpin RNA (shRNA), HBoV1-induced cell death dropped significantly; thus, NLRP3 mediated by ASC appears to be the pattern recognition receptor driving HBoV1 infection-induced pyroptosis. HBoV1 infection induced steady increases in the expression of interleukin 1α (IL-1α) and IL-18. HBoV1 infection was also associated with the marked expression of the antiapoptotic genes BIRC5 and IFI6. When the expression of BIRC5 and/or IFI6 was inhibited by shRNA, the infected cells underwent apoptosis rather than pyroptosis, as indicated by increased cleaved caspase-3 levels and the absence of caspase-1. BIRC5 and/or IFI6 gene inhibition also significantly reduced HBoV1 replication. Thus, HBoV1 infection of human airway epithelial cells activates antiapoptotic proteins that suppress apoptosis and promote pyroptosis. This response may have evolved to confer a replicative advantage, thus allowing HBoV1 to establish a persistent airway epithelial infection. This is the first report of pyroptosis in airway epithelia infected by a respiratory virus. IMPORTANCE Microbial infection of immune cells often induces pyroptosis, which is mediated by a cytosolic protein complex called the inflammasome that senses microbial pathogens and then activates the proinflammatory cytokines IL-1 and IL-18. While virus-infected airway epithelia often activate NLRP3 inflammasomes, studies to date suggest that these viruses kill the airway epithelial cells via the apoptotic or necrotic pathway; involvement of the pyroptosis pathway has not been reported previously. Here, we show for the first time that virus infection of human airway epithelia can also induce pyroptosis. Human bocavirus 1 (HBoV1), a human parvovirus, causes lower respiratory tract infections in young children. This study indicates that HBoV1 kills airway epithelial cells by activating genes that suppress apoptosis and thereby promote pyroptosis. This strategy appears to promote HBoV1 replication and may have evolved to allow HBoV1 to establish persistent infection of human airway epithelia.

scholarly journals In Vitro Modeling of Human Bocavirus 1 Infection of Polarized Primary Human Airway Epithelia

2013 ◽  
Vol 87 (7) ◽  
pp. 4097-4102 ◽  
Author(s):  
X. Deng ◽  
Z. Yan ◽  
Y. Luo ◽  
J. Xu ◽  
F. Cheng ◽  
...  
Keyword(s):  
Human Bocavirus ◽  
Airway Epithelia ◽  
In Vitro Modeling ◽  
Human Airway ◽  
Human Airway Epithelia

scholarly journals Pocket Protein p130/Rb2 Is Required for Efficient Herpes Simplex Virus Type 1 Gene Expression and Viral Replication

2001 ◽  
Vol 75 (15) ◽  
pp. 7149-7160 ◽  
Author(s):  
Ginger L. Ehmann ◽  
Heather A. Burnett ◽  
Steven L. Bachenheimer
Keyword(s):  
Cell Cycle ◽  
Herpes Simplex Virus ◽  
Dna Replication ◽  
Herpes Simplex ◽  
Progeny Virus ◽  
Viral Dna ◽  
Viral Dna Replication ◽  
Pocket Protein ◽  
Simplex Virus

ABSTRACT We have reported previously that herpes simplex virus type 1 (HSV-1) infection disrupts normal progression of the mammalian cell cycle, causing cells to enter a G1-like state. Infected cells were characterized by a decline in cyclin-dependent kinase 2 (CDK2) activities, loss of hyperphosphorylated retinoblastoma protein (pRb), accumulation of E2F-pocket protein complexes, and failure to initiate cellular DNA replication. In the present study, we investigated the role of the pocket proteins pRb, p107, and p130 in HSV-1-dependent cell cycle inhibition and cyclin kinase regulation by infecting murine 3T3 cells derived from wild-type (WT) mouse embryos or embryos with deletions of pRb (pRb−/−), p107 (p107−/−), p130 (p130−/−), or both p130 and p107 (p130−/−/p107−/−). With respect to CDK2 inhibition, viral protein accumulation, viral DNA replication, and progeny virus yield, WT, pRb−/−, and p107−/− cells were essentially identical. In contrast, after infection of p130−/− cells, we observed no inhibition of CDK2 activity, a 5- to 6-h delay in accumulation of viral proteins, an impaired ability to form viral DNA replication compartments, and reduced viral DNA synthesis. As a result, progeny virus yield was reduced 2 logs compared to that in WT cells. Notably, p130−/−/p107−/− double-knockout cells had a virus replication phenotype intermediate between those of the p107−/− and p130−/− cells. We conclude from these studies that p130 is a key factor in regulating aspects of cell cycle progression, as well as the timely expression of viral genes and replication of viral DNA.

scholarly journals Establishment of a Reverse Genetics System for Studying Human Bocavirus in Human Airway Epithelia

2012 ◽  
Vol 8 (8) ◽  
pp. e1002899 ◽  
Author(s):  
Qinfeng Huang ◽  
Xuefeng Deng ◽  
Ziying Yan ◽  
Fang Cheng ◽  
Yong Luo ◽  
...  
Keyword(s):  
Reverse Genetics ◽  
Human Bocavirus ◽  
Airway Epithelia ◽  
Human Airway ◽  
Human Airway Epithelia

scholarly journals Regulation of Minute Virus of Mice NS1 Replicative Functions by Atypical PKCλ In Vivo

2003 ◽  
Vol 77 (1) ◽  
pp. 433-442 ◽  
Author(s):  
Jürg P. F. Nüesch ◽  
Sylvie Lachmann ◽  
Romuald Corbau ◽  
Jean Rommelaere
Keyword(s):  
Dna Replication ◽  
Dominant Negative ◽  
Progeny Virus ◽  
Ns1 Protein ◽  
Viral Dna ◽  
Minute Virus Of Mice ◽  
Viral Dna Replication ◽  
Minute Virus

ABSTRACT Minute virus of mice NS1 protein is a multifunctional phosphoprotein endowed with a variety of enzymatic and regulatory activities necessary for progeny virus particle production. To regulate all of its different functions in the course of a viral infection, NS1 has been proposed to be modulated by posttranslational modifications, in particular, phosphorylation. Indeed, it was shown that the NS1 phosphorylation pattern is altered during the infectious cycle and that the biochemical profile of the protein is dependent on the phosphorylation state of the polypeptide. Moreover, in vitro approaches have identified members of the protein kinase C (PKC) family, in particular, atypical PKC, as regulators of viral DNA replication through the phosphorylation of NS1 residues T435 and S473, thereby activating the protein for DNA unwinding activities. In order to substantiate these findings in vivo, we produced NS1 in the presence of a dominant-negative PKCλ mutant and characterized the purified protein in vitro. The NS1 protein produced under these conditions was found to be only partially phosphorylated and as a consequence to be deficient for viral DNA replication. However, it could be rescued for this viral function by treatment with recombinant activated PKCλ. Our data clearly demonstrate that NS1 is a target for PKCλ phosphorylation in vivo and that this modification is essential for the helicase activity of the viral polypeptide. In addition, the phosphorylation of NS1 at residues T435 and S473 appeared to occur mainly in the nucleus, providing further evidence for the involvement of PKCλ which, unlike PKCζ, accumulates in the nuclear compartment of infected cells.

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