scholarly journals Hitchhiking of Viral Genomes on Cellular Chromosomes

2019 ◽  
Vol 6 (1) ◽  
pp. 275-296 ◽  
Author(s):  
Tami L. Coursey ◽  
Alison A. McBride
Keyword(s):  
Viral Genome ◽  
Viral Infections ◽  
Genome Replication ◽  
Mitotic Chromosomes ◽  
Dna Viruses ◽  
Viral Genomes ◽  
Barr Virus ◽  
Dividing Cells ◽  
Viral Genome Replication ◽  
Epstein Barr

Persistent viral infections require a host cell reservoir that maintains functional copies of the viral genome. To this end, several DNA viruses maintain their genomes as extrachromosomal DNA minichromosomes in actively dividing cells. These viruses typically encode a viral protein that binds specifically to viral DNA genomes and tethers them to host mitotic chromosomes, thus enabling the viral genomes to hitchhike or piggyback into daughter cells. Viruses that use this tethering mechanism include papillomaviruses and the gammaherpesviruses Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus. This review describes the advantages and consequences of persistent extrachromosomal viral genome replication.

scholarly journals A pentameric protein ring with novel architecture is required for herpesviral packaging

2020 ◽  
Author(s):  
Allison L. Didychuk ◽  
Stephanie N. Gates ◽  
Matthew R. Gardner ◽  
Lisa M. Strong ◽  
Andreas Martin ◽  
...  
Keyword(s):  
Viral Genome ◽  
Molecular Motor ◽  
Dna Viruses ◽  
Dna Mutation ◽  
Viral Genomes ◽  
Barr Virus ◽  
Double Stranded Dna ◽  
Accessory Factor ◽  
Epstein Barr ◽  
Positively Charged

Genome packaging in large double-stranded DNA viruses requires a powerful molecular motor to force the viral genome into nascent capsids. This process appears mechanistically similar in two evolutionarily distant viruses, the herpesviruses and the tailed bacteriophages, which infect different kingdoms of life. While the motor and mechanism as a whole are thought to be conserved, accessory factors that influence packaging are divergent and poorly understood, despite their essential roles. An accessory factor required for herpesviral packaging is encoded by ORF68 in the oncogenic virus Kaposi’s sarcoma-associated herpesvirus (KSHV), whose homolog in Epstein Barr Virus (EBV) is BFLF1. Here, we present structures of both KSHV ORF68 and EBV BFLF1, revealing that these proteins form a highly similar homopentameric ring. The central channel of this ring is positively charged, and we demonstrate that this region of KSHV ORF68 binds double-stranded DNA. Mutation of individual positively charged residues within but not outside the channel ablates DNA binding, and in the context of KSHV infection these mutants fail to package the viral genome or produce progeny virions. Thus, we propose a model in which ORF68 facilitates the transfer of newly replicated viral genomes to the packaging motor.

scholarly journals Sumoylation of the Epstein-Barr Virus BZLF1 Protein Inhibits Its Transcriptional Activity and Is Regulated by the Virus-Encoded Protein Kinase

2010 ◽  
Vol 84 (9) ◽  
pp. 4383-4394 ◽  
Author(s):  
Stacy R. Hagemeier ◽  
Sarah J. Dickerson ◽  
Qiao Meng ◽  
Xianming Yu ◽  
Janet E. Mertz ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Viral Genome ◽  
Epstein Barr Virus ◽  
Transcriptional Activity ◽  
Genome Replication ◽  
Wild Type ◽  
Barr Virus ◽  
293 Cells ◽  
Viral Genome Replication ◽  
Epstein Barr

ABSTRACT The Epstein-Barr virus (EBV) immediate-early protein BZLF1 (Z) mediates the switch between latent and lytic EBV infection. Z not only activates early lytic viral gene transcription but also plays a direct role in lytic viral genome replication. Although a small fraction of Z is known to be sumoylated, the effects of this posttranslational modification on various different Z functions have not been well defined. In this report, we show that only the lysine at amino acid residue 12 is required for the sumoylation of Z, and that Z can be sumoylated by SUMO isoforms 1, 2, and 3. We also demonstrate that the sumo-defective Z mutants ZK12A and ZK12R have enhanced transcriptional activity. The sumoylated and nonsumoylated forms of Z were found to have a similar cellular location, both being localized primarily within the nuclear matrix. The Z sumo-defective mutants were, however, partially defective for disrupting promyelocytic leukemia (PML) bodies compared to the ability of wild-type Z. In addition, we show that lytic viral genome replication does not require the sumoylation of Z, although a Z mutant altered at both amino acids 12 and 13 is replication defective. Furthermore, we show that the sumoylation of Z is greatly increased (from less than 1 to about 11%) in lytically induced 293 cells infected with an EBV mutant virus deleted for the EBV-encoded protein kinase (EBV-PK) compared to that of 293 cells infected with wild-type EBV, and that the overexpression of EBV-PK leads to the reduced sumoylation of Z in EBV-negative cells. Our results suggest that the sumoylation of Z helps to promote viral latency, and that EBV-PK inhibits Z sumoylation during viral reactivation.

scholarly journals Early Epstein-Barr Virus Genomic Diversity and Convergence toward the B95.8 Genome in Primary Infection

2017 ◽  
Vol 92 (2) ◽  
Author(s):  
Eric R. Weiss ◽  
Susanna L. Lamers ◽  
Jennifer L. Henderson ◽  
Alexandre Melnikov ◽  
Mohan Somasundaran ◽  
...  
Keyword(s):  
B Cell ◽  
Viral Genome ◽  
Primary Infection ◽  
Epstein Barr Virus ◽  
Genome Diversity ◽  
Genome Sequences ◽  
Viral Genomes ◽  
Barr Virus ◽  
Epstein Barr ◽  
Cell Fractions

ABSTRACTOver 90% of the world's population is persistently infected with Epstein-Barr virus. While EBV does not cause disease in most individuals, it is the common cause of acute infectious mononucleosis (AIM) and has been associated with several cancers and autoimmune diseases, highlighting a need for a preventive vaccine. At present, very few primary, circulating EBV genomes have been sequenced directly from infected individuals. While low levels of diversity and low viral evolution rates have been predicted for double-stranded DNA (dsDNA) viruses, recent studies have demonstrated appreciable diversity in common dsDNA pathogens (e.g., cytomegalovirus). Here, we report 40 full-length EBV genome sequences obtained from matched oral wash and B cell fractions from a cohort of 10 AIM patients. Both intra- and interpatient diversity were observed across the length of the entire viral genome. Diversity was most pronounced in viral genes required for establishing latent infection and persistence, with appreciable levels of diversity also detected in structural genes, including envelope glycoproteins. Interestingly, intrapatient diversity declined significantly over time (P< 0.01), and this was particularly evident on comparison of viral genomes sequenced from B cell fractions in early primary infection and convalescence (P< 0.001). B cell-associated viral genomes were observed to converge, becoming nearly identical to the B95.8 reference genome over time (Spearman rank-order correlation test;r= −0.5589,P= 0.0264). The reduction in diversity was most marked in the EBV latency genes. In summary, our data suggest independent convergence of diverse viral genome sequences toward a reference-like strain within a relatively short period following primary EBV infection.IMPORTANCEIdentification of viral proteins with low variability and high immunogenicity is important for the development of a protective vaccine. Knowledge of genome diversity within circulating viral populations is a key step in this process, as is the expansion of intrahost genomic variation during infection. We report full-length EBV genomes sequenced from the blood and oral wash of 10 individuals early in primary infection and during convalescence. Our data demonstrate considerable diversity within the pool of circulating EBV strains, as well as within individual patients. Overall viral diversity decreased from early to persistent infection, particularly in latently infected B cells, which serve as the viral reservoir. Reduction in B cell-associated viral genome diversity coincided with a convergence toward a reference-like EBV genotype. Greater convergence positively correlated with time after infection, suggesting that the reference-like genome is the result of selection.

scholarly journals Tetrameric Ring Formation of Epstein-Barr Virus Polymerase Processivity Factor Is Crucial for Viral Replication

2010 ◽  
Vol 84 (24) ◽  
pp. 12589-12598 ◽  
Author(s):  
Sanae Nakayama ◽  
Takayuki Murata ◽  
Yoshihiro Yasui ◽  
Kazutaka Murayama ◽  
Hiroki Isomura ◽  
...  
Keyword(s):  
Viral Replication ◽  
Epstein Barr Virus ◽  
Ring Formation ◽  
Genome Replication ◽  
Wild Type ◽  
Barr Virus ◽  
Viral Genome Replication ◽  
Processivity Factor ◽  
Epstein Barr

ABSTRACT The Epstein-Barr virus BMRF1 DNA polymerase processivity factor, which is essential for viral genome replication, exists mainly as a C-shaped head-to-head homodimer but partly forms a ring-shaped tetramer through tail-to-tail association. Based on its molecular structure, several BMRF1 mutant viruses were constructed to examine their influence on viral replication. The R256E virus, which has a severely impaired capacity for DNA binding and polymerase processivity, failed to form replication compartments, resulting in interference of viral replication, while the C95E mutation, which impairs head-to-head contact in vitro, unexpectedly hardly affected the viral replication. Also, surprisingly, replication of the C206E virus, which is expected to have impairment of tail-to-tail contact, was severely restricted, although the mutant protein possesses the same in vitro biochemical activities as the wild type. Since the tail-to-tail contact surface is smaller than that of the head-to-head contact area, its contribution to ring formation might be essential for viral replication.

scholarly journals A pentameric protein ring with novel architecture is required for herpesviral packaging

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Allison L Didychuk ◽  
Stephanie N Gates ◽  
Matthew R Gardner ◽  
Lisa M Strong ◽  
Andreas Martin ◽  
...  
Keyword(s):  
Viral Genome ◽  
Molecular Motor ◽  
Homologous Proteins ◽  
Dna Mutation ◽  
Viral Genomes ◽  
Barr Virus ◽  
Double Stranded Dna ◽  
Accessory Factors ◽  
Epstein Barr ◽  
Positively Charged

Genome packaging in large double-stranded DNA viruses requires a powerful molecular motor to force the viral genome into nascent capsids, which involves essential accessory factors that are poorly understood. Here, we present structures of two such accessory factors from the oncogenic herpesviruses Kaposi’s sarcoma-associated herpesvirus (KSHV; ORF68) and Epstein–Barr virus (EBV; BFLF1). These homologous proteins form highly similar homopentameric rings with a positively charged central channel that binds double-stranded DNA. Mutation of individual positively charged residues within but not outside the channel ablates DNA binding, and in the context of KSHV infection, these mutants fail to package the viral genome or produce progeny virions. Thus, we propose a model in which ORF68 facilitates the transfer of newly replicated viral genomes to the packaging motor.

scholarly journals Novel patterns of the Epstein-Barr nuclear antigen (EBNA-1) V-Val subtype in EBV-associated nasopharyngeal carcinoma from Vietnam

2019 ◽  
Vol 22 (1) ◽  
pp. 61-68
Author(s):  
LD Thuan ◽  
ND Kha ◽  
NT Minh ◽  
LHA Thuy
Keyword(s):  
Amino Acid ◽  
Nasopharyngeal Carcinoma ◽  
Asian Country ◽  
Nuclear Antigen ◽  
Genome Replication ◽  
Nested Polymerase Chain Reaction ◽  
Barr Virus ◽  
Viral Genome Replication ◽  
Epstein Barr ◽  
Epstein Barr Nuclear Antigen

AbstractThe Epstein-Barr nuclear antigen 1 (EBNA-1) gene, plays a key role in viral infection, immortalization, viral genome replication, transcription and maintenance, and is the frequently detected gene, protein in both latent and lytic stage of Epstein-Barr virus (EBV). Based on the amino acid at position 487, EBNA-1 was classified into five subtypes, including P-Ala, P-Thr, V-Val, V-Pro and V-Leu. In Vietnam, an Asian country with a high incidence, mortality rates of nasopharyngeal carcinoma (NPC), had limited research on the EBNA-1 variation. Therefore, the aim of the current study was to identify the pattern of the EBNA-1 V-Val subtype in Vietnamese NPC patients, for its value further applied in NPC patients. Fifty-eight NPC biopsy samples were collected from local patients, analyzed by nested-polymerase chain reaction (nested-PCR), sequencing and compared to a previous B95-8 prototype sequence. Four EBNA-1 subtypes, including V-Val (35/44, 79.55%), P-Ala (2/44, 4.55%), P-Thr (5/44, 11.36%), and V-Leu (2/44, 4.55%), were observed in 44/58 samples. The sequences of the V-Val subtype were compared to the B95-8 prototype, resulting in five patterns, contained seven consensus changes, including five amino acid changes at positions 487, 499, 502, 524, 594, and two silent changes at residues 520 and 553. Of these, four of five, patterns were identified as novel patterns of the V-Val subtype, showing the different changes of amino acids at positions 492, 528, 529, 553, 585 and 588, by comparison with previous studies of V-Val EBNA-1. Those data suggested the profile of variation patterns of the EBNA-1 gene, related to geographic distribution, in Vietnamese NPC patients.

scholarly journals Uncovering the Role of the E1 Protein in Different Stages of Human Papillomavirus 18 Genome Replication

2020 ◽  
Vol 94 (20) ◽  
Author(s):  
Alla Piirsoo ◽  
Martin Kala ◽  
Eve Sankovski ◽  
Mart Ustav ◽  
Marko Piirsoo
Keyword(s):  
Life Cycle ◽  
Viral Genome ◽  
Copy Number ◽  
Genome Replication ◽  
Dependent Manner ◽  
Infection Cycle ◽  
Viral Genomes ◽  
E1 Protein ◽  
Viral Genome Replication

ABSTRACT The life cycle of human papillomaviruses (HPVs) comprises three distinct phases of DNA replication: initial amplification, maintenance of the genome copy number at a constant level, and vegetative amplification. The viral helicase E1 is one of the factors required for the initiation of HPV genome replication. However, the functions of the E1 protein during other phases of the viral life cycle are largely uncharacterized. Here, we studied the role of the HPV18 E1 helicase in three phases of viral genome replication by downregulating E1 expression using RNA interference or inducing degradation of the E1 protein via inhibition of casein kinase 2α expression or catalytic activity. We generated a novel modified HPV18 genome expressing Nanoluc and tagged E1 and E2 proteins and created several stable HPV18-positive cell lines. We showed that, in contrast to initial amplification of the HPV18 genome, other phases of viral genome replication involve also an E1-independent mechanism. We characterize two distinct populations of HPV18 replicons existing during the maintenance and vegetative amplification phases. We show that a subset of these replicons, including viral genome monomers, replicate in an E1-dependent manner, while some oligomeric forms of the HPV18 genome replicate independently of E1 function. IMPORTANCE Human papillomavirus (HPV) infections pose serious medical problem. To date, there are no HPV-specific antivirals available due to poor understanding of the molecular mechanisms of virus infection cycle. The infection cycle of HPV involves initial amplification of the viral genomes and maintenance of the viral genomes with a constant copy number, followed by another round of viral genome amplification and new viral particle formation. The viral protein E1 is critical for the initial amplification of the viral genome. However, E1 involvement in other phases of the viral life cycle has remained controversial. In the present study, we show that at least two different replication modes of the HPV18 genome are undertaken simultaneously during the maintenance and vegetative amplification phases, i.e., replication of the majority of the HPV18 genome proceeds under the control of the host cell replication machinery without E1 function, whereas a minority of the genome replicates in an E1-dependent manner.

scholarly journals Analysis of the Replication Mechanisms of the Human Papillomavirus Genomes

2021 ◽  
Vol 12 ◽  
Author(s):  
Lisett Liblekas ◽  
Alla Piirsoo ◽  
Annika Laanemets ◽  
Eva-Maria Tombak ◽  
Airiin Laaneväli ◽  
...  
Keyword(s):  
Life Cycle ◽  
Viral Genome ◽  
Maintenance Phase ◽  
Viral Life Cycle ◽  
Human Papillomaviruses ◽  
Genome Replication ◽  
Viral Genomes ◽  
Viral Genome Replication ◽  
Infected Cells ◽  
Cell Genome

The life-cycle of human papillomaviruses (HPVs) includes three distinct phases of the viral genome replication. First, the viral genome is amplified in the infected cells, and this amplification is often accompanied by the oligomerization of the viral genomes. Second stage includes the replication of viral genomes in concert with the host cell genome. The viral genome is further amplified during the third stage of the viral-life cycle, which takes place only in the differentiated keratinocytes. We have previously shown that the HPV18 genomes utilize at least two distinct replication mechanisms during the initial amplification. One of these mechanisms is a well-described bidirectional replication via theta type of replication intermediates. The nature of another replication mechanism utilized by HPV18 involves most likely recombination-dependent replication. In this paper, we show that the usage of different replication mechanisms is a property shared also by other HPV types, namely HPV11 and HPV5. We further show that the emergence of the recombination dependent replication coincides with the oligomerization of the viral genomes and is dependent on the replicative DNA polymerases. We also show that the oligomeric genomes of HPV18 replicate almost exclusively using recombination dependent mechanism, whereas monomeric HPV31 genomes replicate bi-directionally during the maintenance phase of the viral life-cycle.

scholarly journals Inhibition of E2 Binding to Brd4 Enhances Viral Genome Loss and Phenotypic Reversion of Bovine Papillomavirus-Transformed Cells

2005 ◽  
Vol 79 (23) ◽  
pp. 14956-14961 ◽  
Author(s):  
Jianxin You ◽  
Michal-Ruth Schweiger ◽  
Peter M. Howley
Keyword(s):  
Viral Genome ◽  
Mitotic Chromosome ◽  
Transformed Cells ◽  
Bovine Papillomavirus ◽  
Complete Elimination ◽  
Mitotic Chromosomes ◽  
Viral Dna ◽  
Viral Genomes ◽  
Dividing Cells ◽  
Phenotypic Reversion

ABSTRACT The bovine papillomavirus E2 protein tethers the viral genomes to mitotic chromosomes in dividing cells through binding to the C-terminal domain (CTD) of Brd4. Expression of the Brd4-CTD competes the binding of E2 to endogenous Brd4 in cells. Here we extend our previous study that identified Brd4 as the E2 mitotic chromosome receptor to show that Brd4-CTD expression released the viral DNA from mitotic chromosomes in BPV-1 transformed cells. Furthermore, stable expression of Brd4-CTD enhanced the frequency of morphological reversion of BPV-1 transformed C127 cells resulting in the complete elimination of the viral DNA in the resulting flat revertants.

Association of normal oral mucosa with DNA of the main types of oncogenic viruses

2020 ◽  
pp. 60-63
Author(s):  
S.I. Kutukova ◽  
A.B. Chukhlovin ◽  
A.I. Yaremenko ◽  
Yu.V. Ivaskova ◽  
A.Ya. Razumova ◽  
...  
Keyword(s):  
Oral Mucosa ◽  
Epstein Barr Virus ◽  
Oncogenic Viruses ◽  
Viral Dna ◽  
Dna Viruses ◽  
Normal Oral Mucosa ◽  
Barr Virus ◽  
Ebv Dna ◽  
Epstein Barr ◽  
Hpv 18

The aim of the study was to assess the prevalence of DNA viruses (HSV I and II, CMV, EBV, HPV6.11, HPV16 and HPV18) in the native oral mucosa of healthy volunteers (n=50; 30 men (60.0%), 20 women (40.0%); 25—74 years, median age — 55.0 years (95% CI 47.60-56.76)). All samples of the normal oral mucosa were detected by real-time PCR to detect viral DNA. The majority of the examined — 76% (33/50) — revealed the DNA: one type of viral DNA in 17 (38.00%) of the examined, a combination of the two types in 14 (28.00%). In the normal oral mucosa, DNA of Epstein-Barr virus was significantly more often detected: 15 (30.00%) (p = 0.0276) and human papilloma viruses 27 (54.00%) (p <0.0001), especially HPV-18 (24 (48.00%)): mono-association in 9 (18.00%) examined and in 7 (14.00%) in combination with EBV DNA (p = 0.0253).

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