scholarly journals Slow Infection due to Lowering the Amount of Intact versus Empty Particles Is a Characteristic Feature of Coxsackievirus B5 Dictated by the Structural Proteins

2019 ◽  
Vol 93 (20) ◽  
Author(s):  
Paula Turkki ◽  
Mira Laajala ◽  
Marie Stark ◽  
Helena Vandesande ◽  
Heidi Sallinen-Dal Maso ◽  
...  
Keyword(s):  
Persistent Infection ◽  
Genetic Material ◽  
Structural Proteins ◽  
Close Relative ◽  
Myocardial Inflammation ◽  
Nonstructural Proteins ◽  
Persistent Infections ◽  
Slowing Down ◽  
Key Factor ◽  
Rd Cells

ABSTRACT Enterovirus B species typically cause a rapid cytolytic infection leading to efficient release of progeny viruses. However, they are also capable of persistent infections in tissues, which are suggested to contribute to severe chronic states such as myocardial inflammation and type 1 diabetes. In order to understand the factors contributing to differential infection strategies, we constructed a chimera by combining the capsid proteins from fast-cytolysis-causing echovirus 1 (EV1) with nonstructural proteins from coxsackievirus B5 (CVB5), which shows persistent infection in RD cells. The results showed that the chimera behaved similarly to parental EV1, leading to efficient cytolysis in both permissive A549 and semipermissive RD cells. In contrast to EV1 and the chimera, CVB5 replicated slowly in permissive cells and showed persistent infection in semipermissive cells. However, there was no difference in the efficiency of uptake of CVB5 in A549 or RD cells in comparison to the chimera or EV1. CVB5 batches constantly contained significant amounts of empty capsids, also in comparison to CVB5's close relative CVB3. During successive passaging of batches containing only intact CVB5, increasing amounts of empty and decreasing amounts of infective capsids were produced. Our results demonstrate that the increase in the amount of empty particles and the lowering of the amount of infective particles are dictated by the CVB5 structural proteins, leading to slowing down of the infection between passages. Furthermore, the key factor for persistent infection is the small amount of infective particles produced, not the high number of empty particles that accumulate. IMPORTANCE Enteroviruses cause several severe diseases, with lytic infections that lead to rapid cell death but also persistent infections that are more silent and lead to chronic states of infection. Our study compared a cytolytic echovirus 1 infection to persistent coxsackievirus B5 infection by making a chimera with the structural proteins of echovirus 1 and the nonstructural proteins of coxsackievirus B5. Coxsackievirus B5 infection was found to lead to the production of a high number of empty viruses (empty capsids) that do not contain genetic material and are unable to continue the infection. Coinciding with the high number of empty capsids, the amount of infective virions decreased. This characteristic property was not observed in the constructed chimera virus, suggesting that structural proteins are in charge of these phenomena. These results shed light on the mechanisms that may cause persistent infections. Understanding events leading to efficient or inefficient infections is essential in understanding virus-caused pathologies.

scholarly journals Nora virus, a persistent virus in Drosophila, defines a new picorna-like virus family

2006 ◽  
Vol 87 (10) ◽  
pp. 3045-3051 ◽  
Author(s):  
Mazen S. Habayeb ◽  
Sophia K. Ekengren ◽  
Dan Hultmark
Keyword(s):  
Persistent Infection ◽  
Open Reading Frames ◽  
Close Relative ◽  
Virus Family ◽  
Viral Genomes ◽  
Persistent Infections ◽  
New Family ◽  
Nora Virus ◽  
Persistent Virus ◽  
Viral Sequences

Several viruses, including picornaviruses, are known to establish persistent infections, but the mechanisms involved are poorly understood. Here, a novel picorna-like virus, Nora virus, which causes a persistent infection in Drosophila melanogaster, is described. It has a single-stranded, positive-sense genomic RNA of 11879 nt, followed by a poly(A) tail. Unlike other picorna-like viruses, the genome has four open reading frames (ORFs). One ORF encodes a picornavirus-like cassette of proteins for virus replication, including an iflavirus-like RNA-dependent RNA polymerase and a helicase that is related to those of mammalian picornaviruses. The three other ORFs are not closely related to any previously described viral sequences. The unusual sequence and genome organization in Nora virus suggest that it belongs to a new family of picorna-like viruses. Surprisingly, Nora virus could be detected in all tested D. melanogaster laboratory stocks, as well as in wild-caught material. The viral titres varied enormously, between 104 and 1010 viral genomes per fly in different stocks, without causing obvious pathological effects. The virus was also found in Drosophila simulans, a close relative of D. melanogaster, but not in more distantly related Drosophila species. It will now be possible to use Drosophila genetics to study the factors that control this persistent infection.

scholarly journals Structure and Function of Major SARS-CoV-2 and SARS-CoV Proteins

2021 ◽  
Vol 15 ◽  
pp. 117793222110258
Author(s):  
Ritesh Gorkhali ◽  
Prashanna Koirala ◽  
Sadikshya Rijal ◽  
Ashmita Mainali ◽  
Adesh Baral ◽  
...  
Keyword(s):  
Genomic Organization ◽  
Membrane Vesicles ◽  
Structural Proteins ◽  
Host Immune System ◽  
Accessory Proteins ◽  
Nonstructural Proteins ◽  
N Protein ◽  
Small Proteins ◽  
Methylation Mark ◽  
And Function

SARS-CoV-2 virus, the causative agent of COVID-19 pandemic, has a genomic organization consisting of 16 nonstructural proteins (nsps), 4 structural proteins, and 9 accessory proteins. Relative of SARS-CoV-2, SARS-CoV, has genomic organization, which is very similar. In this article, the function and structure of the proteins of SARS-CoV-2 and SARS-CoV are described in great detail. The nsps are expressed as a single or two polyproteins, which are then cleaved into individual proteins using two proteases of the virus, a chymotrypsin-like protease and a papain-like protease. The released proteins serve as centers of virus replication and transcription. Some of these nsps modulate the host’s translation and immune systems, while others help the virus evade the host immune system. Some of the nsps help form replication-transcription complex at double-membrane vesicles. Others, including one RNA-dependent RNA polymerase and one exonuclease, help in the polymerization of newly synthesized RNA of the virus and help minimize the mutation rate by proofreading. After synthesis of the viral RNA, it gets capped. The capping consists of adding GMP and a methylation mark, called cap 0 and additionally adding a methyl group to the terminal ribose called cap1. Capping is accomplished with the help of a helicase, which also helps remove a phosphate, two methyltransferases, and a scaffolding factor. Among the structural proteins, S protein forms the receptor of the virus, which latches on the angiotensin-converting enzyme 2 receptor of the host and N protein binds and protects the genomic RNA of the virus. The accessory proteins found in these viruses are small proteins with immune modulatory roles. Besides functions of these proteins, solved X-ray and cryogenic electron microscopy structures related to the function of the proteins along with comparisons to other coronavirus homologs have been described in the article. Finally, the rate of mutation of SARS-CoV-2 residues of the proteome during the 2020 pandemic has been described. Some proteins are mutated more often than other proteins, but the significance of these mutation rates is not fully understood.

scholarly journals Simultaneous quantification of Vibrio metoecus and Vibrio cholerae with its O1 serogroup and toxigenic subpopulations in environmental reservoirs

2019 ◽  
Author(s):  
Tania Nasreen ◽  
Nora A. S. Hussain ◽  
Mohammad Tarequl Islam ◽  
Fabini D. Orata ◽  
Paul C. Kirchberger ◽  
...  
Keyword(s):  
Opportunistic Infections ◽  
Limit Of Detection ◽  
Spatial Scales ◽  
Genetic Material ◽  
Size Fraction ◽  
Environmental Water ◽  
Close Relative ◽  
Toxin Gene ◽  
Actual Distribution ◽  
Temporal And Spatial

ABSTRACTVibrio metoecus is a recently described and little studied causative agent of opportunistic infections in humans, often coexisting with V. cholerae in aquatic environments. However, the relative abundance of V. metoecus with V. cholerae and their population dynamics in aquatic reservoirs is still unknown. We developed a multiplex qPCR assay with a limit of detection of three copies per reaction to simultaneously quantify total V. metoecus and V. cholerae abundance, as well as the toxigenic and O1 serogroup subpopulations of V. cholerae from environmental samples. Four different genes were targeted as specific markers for individual Vibrio species or subpopulations; viuB, a gene encoding a vibriobactin utilization protein, was used to quantify the total V. cholerae population. The cholera toxin gene ctxA provided an estimation of toxigenic V. cholerae abundance, while the rfbO1 gene specifically detected and quantified V. cholerae belonging to the O1 serogroup, which includes almost all lineages of the species responsible for the majority of past and ongoing cholera pandemics. To measure V. metoecus abundance, the gene mcp, encoding methyl accepting chemotaxis protein, was used. Marker specificity was confirmed by testing several isolates of V. cholerae and V. metoecus alongside negative controls of isolates within and outside of the Vibrio genus. Analysis of environmental water samples collected from four different geographic locations including cholera-endemic (Dhaka, Kuakata and Mathbaria in Bangladesh) and non-endemic (Oyster Pond in Falmouth, Massachusetts, USA) regions showed that V. metoecus was only present in the USA site, recurring seasonally. Within the coastal USA site, the non-toxigenic O1 serogroup represented up to ∼18% of the total V. cholerae population. V. cholerae toxigenic O1 serogroup was absent or present in low abundance in coastal Bangladesh (Kuakata and Mathbaria) but constituted a relatively high proportion of the total V. cholerae population sustained throughout the year in inland Bangladesh (Dhaka). A preference for host/particle attachment was observed, as the majority of cells from both Vibrio species (>90%) were identified in the largest water size fraction sampled, composed of particles or organisms >63 μm and their attached bacteria. This is the first study to apply a culture-independent method to quantify V. cholerae or V. metoecus directly in environmental reservoirs of areas endemic and non-endemic for cholera on significant temporal and spatial scales.SIGNIFICANCECholera is a life-threatening disease that requires immediate intervention; it is of prime importance to have fast, accurate and sensitive means to detect V. cholerae. Consistent environmental monitoring of the abundance of V. cholerae along with its toxigenic and O1 serogroup subpopulations could facilitate the determination of the actual distribution of this organism in aquatic reservoirs and thus help to predict an outbreak before it strikes. The lack of substantial temporal and spatial environmental sampling, along with specific quantitative measures, has made this goal elusive so far. The same is true for V. metoecus, a close relative of V. cholerae which has been associated with several clinical infections and could likely pose an emerging threat, readily exchanging genetic material with its more famous relative.

scholarly journals Recent Progress on the Versatility of Virus-Like Particles

Vaccines ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 139 ◽  
Author(s):  
Ciying Qian ◽  
Xinlin Liu ◽  
Qin Xu ◽  
Zhiping Wang ◽  
Jie Chen ◽  
...  
Keyword(s):  
Immune Responses ◽  
Small Molecules ◽  
Genetic Material ◽  
Structural Proteins ◽  
Cell Penetration ◽  
Virus Like Particles ◽  
Humoral Immune ◽  
Specific Targeting ◽  
Humoral Immune Responses ◽  
Antigenic Epitopes

Virus-like particles (VLPs) are multimeric nanostructures composed of one or more structural proteins of a virus in the absence of genetic material. Having similar morphology to natural viruses but lacking any pathogenicity or infectivity, VLPs have gradually become a safe substitute for inactivated or attenuated vaccines. VLPs can achieve tissue-specific targeting and complete and effective cell penetration. With highly ordered epitope repeats, VLPs have excellent immunogenicity and can induce strong cellular and humoral immune responses. In addition, as a type of nanocarrier, VLPs can be used to display antigenic epitopes or deliver small molecules. VLPs have thus become powerful tools for vaccinology and biomedical research. This review highlights the versatility of VLPs in antigen presentation, drug delivery, and vaccine technology.

Persistent Infection of Human Oligodendrocytic and Neuroglial Cell Lines by Human Coronavirus 229E

1999 ◽  
Vol 73 (4) ◽  
pp. 3326-3337 ◽  
Author(s):  
Nathalie Arbour ◽  
Sophie Ekandé ◽  
Geneviève Côté ◽  
Claude Lachance ◽  
Fanny Chagnon ◽  
...  
Keyword(s):  
Nervous System ◽  
Cell Lines ◽  
Persistent Infection ◽  
Viral Antigen ◽  
Infectious Virus ◽  
Acute Infection ◽  
Viral Rna ◽  
Persistent Infections ◽  
Virus Progeny

ABSTRACT Human coronaviruses (HuCV) cause common colds. Previous reports suggest that these infectious agents may be neurotropic in humans, as they are for some mammals. With the long-term aim of providing experimental evidence for the neurotropism of HuCV and the establishment of persistent infections in the nervous system, we have evaluated the susceptibility of various human neural cell lines to acute and persistent infection by HuCV-229E. Viral antigen, infectious virus progeny and viral RNA were monitored during both acute and persistent infections. The astrocytoma cell lines U-87 MG, U-373 MG, and GL-15, as well as neuroblastoma SK-N-SH, neuroglioma H4, and oligodendrocytic MO3.13 cell lines, were all susceptible to an acute infection by HuCV-229E. The CHME-5 immortalized fetal microglial cell line was not susceptible to infection by this virus. The MO3.13 and H4 cell lines also sustained a persistent viral infection, as monitored by detection of viral antigen and infectious virus progeny. Sequencing of the S1 gene from viral RNA after ∼130 days of infection showed two point mutations, suggesting amino acid changes during persistent infection of MO3.13 cells but none for H4 cells. Thus, persistent in vitro infection did not generate important changes in the S1 portion of the viral spike protein, which was shown for murine coronaviruses to bear hypervariable domains and to interact with cellular receptor. These results are consistent with the potential persistence of HuCV-229E in cells of the human nervous system, such as oligodendrocytes and possibly neurons, and the virus’s apparent genomic stability.

scholarly journals Persistent Equine Arteritis Virus Infection in HeLa Cells

2008 ◽  
Vol 82 (17) ◽  
pp. 8456-8464 ◽  
Author(s):  
Jianqiang Zhang ◽  
Peter J. Timoney ◽  
N. James MacLachlan ◽  
William H. McCollum ◽  
Udeni B. R. Balasuriya
Keyword(s):  
Persistent Infection ◽  
Single Point ◽  
Equine Arteritis Virus ◽  
Structural Proteins ◽  
Single Point Mutation ◽  
Recombinant Viruses ◽  
L Cells ◽  
Passage Number ◽  
Human Cervix

ABSTRACT The horse-adapted virulent Bucyrus (VB) strain of equine arteritis virus (EAV) established persistent infection in high-passage-number human cervix cells (HeLa-H cells; passages 170 to 221) but not in low-passage-number human cervix cells (HeLa-L cells; passages 95 to 115) or in several other cell lines that were evaluated. However, virus recovered from the 80th passage of the persistently infected HeLa-H cells (HeLa-H-EAVP80) readily established persistent infection in HeLa-L cells. Comparative sequence analysis of the entire genomes of the VB and HeLa-H-EAVP80 viruses identified 16 amino acid substitutions, including 4 in the replicase (nsp1, nsp2, nsp7, and nsp9) and 12 in the structural proteins (E, GP2, GP3, GP4, and GP5). Reverse genetic studies clearly showed that substitutions in the structural proteins but not the replicase were responsible for the establishment of persistent infection in HeLa-L cells by the HeLa-H-EAVP80 virus. It was further demonstrated that recombinant viruses with substitutions in the minor structural proteins E and GP2 or GP3 and GP4 were unable to establish persistent infection in HeLa-L cells but that recombinant viruses with combined substitutions in the E (Ser53→Cys and Val55→Ala), GP2 (Leu15→Ser, Trp31→Arg, Val87→Leu, and Ala112→Thr), GP3 (Ser115→Gly and Leu135→Pro), and GP4 (Tyr4→His and Ile109→Phe) proteins or with a single point mutation in the GP5 protein (Pro98→Leu) were able to establish persistent infection in HeLa-L cells. In summary, an in vitro model of EAV persistence in cell culture was established for the first time. This system can provide a valuable model for studying virus-host cell interactions, especially virus-receptor interactions.

scholarly journals Bacteriophage φYeO3-12, Specific forYersinia enterocolitica Serotype O:3, Is Related to Coliphages T3 and T7

2000 ◽  
Vol 182 (18) ◽  
pp. 5114-5120 ◽  
Author(s):  
Maria Pajunen ◽  
Saija Kiljunen ◽  
Mikael Skurnik
Keyword(s):  
Physical Map ◽  
Burst Size ◽  
Restriction Enzymes ◽  
Structural Proteins ◽  
Close Relative ◽  
Lytic Phage ◽  
Serotype O ◽  
One Step ◽  
Phage Capsid ◽  
Phage Receptor

Bacteriophage φYeO3-12 is a lytic phage of Yersinia enterocolitica serotype O:3. The phage receptor is the lipopolysaccharide O chain of this serotype that consists of the rare sugar 6-deoxy-l-altropyranose. A one-step growth curve of φYeO3-12 revealed eclipse and latent periods of 15 and 25 min, respectively, with a burst size of about 120 PFU per infected cell. In electron microscopy φYeO3-12 virions showed pentagonal outlines, indicating their icosahedral nature. The phage capsid was shown to be composed of at least 10 structural proteins, of which a protein of 43 kDa was predominant. N-terminal sequences of three structural proteins were determined, two of them showing strong homology to structural proteins of coliphages T3 and T7. The phage genome was found to consist of a double-stranded DNA molecule of 40 kb without cohesive ends. A physical map of the phage DNA was constructed using five restriction enzymes. The phage infection could be effectively neutralized using serum from a rabbit immunized with whole φYeO3-12 particles. The antiserum also neutralized T3 infection, although not as efficiently as that of φYeO3-12. φYeO3-12 was found to share, in addition to the N-terminal sequence homology, several common features with T3, including morphology and nonsubjectibility to F exclusion. The evidence conclusively indicated that φYeO3-12 is the first close relative of phage T3 to be described.

The Numerical Simulation of Moisture Transportation in Unsaturated Concrete of Underwater Tunnel

2013 ◽  
Vol 275-277 ◽  
pp. 1190-1193
Author(s):  
Yuan Zhu Zhang ◽  
Xiao Zhen Li ◽  
Xin Jiang Wei
Keyword(s):  
Water Saturation ◽  
Nonlinear Partial Differential Equation ◽  
Moisture Diffusion ◽  
Tunnel Wall ◽  
Slowing Down ◽  
Key Factor ◽  
Underwater Concrete ◽  
Underwater Tunnel ◽  
Over Time

Moisture transportation is a key factor to affect the long-term safety of underwater concrete tunnel. According to the inside and outside environment of tunnel, the moisture transportation equation in unsaturated concrete of underwater tunnel was raised. Finite difference method was adopted to solve the nonlinear partial differential equation of moisture diffusion. The study shows that the changes of water saturation in concrete are mainly concentrated in the surface of tunnel wall and amplitude is gradually slowing down over time. Saturation changes greater in the outside than inside. The wetting state is more obvious than drying state.

scholarly journals Production of Pseudoinfectious Yellow Fever Virus with a Two-Component Genome

2007 ◽  
Vol 81 (21) ◽  
pp. 11737-11748 ◽  
Author(s):  
Alexandr V. Shustov ◽  
Peter W. Mason ◽  
Ilya Frolov
Keyword(s):  
Yellow Fever ◽  
Yellow Fever Virus ◽  
Fever Virus ◽  
Structural Proteins ◽  
Multiplicity Of Infection ◽  
Nonstructural Proteins ◽  
Replication Complex ◽  
Packaging Process ◽  
E Protein ◽  
Two Component

ABSTRACT Application of genetically modified, deficient-in-replication flaviviruses that are incapable of developing productive, spreading infection is a promising means of designing safe and effective vaccines. Here we describe a two-component genome yellow fever virus (YFV) replication system in which each of the genomes encodes complete sets of nonstructural proteins that form the replication complex but expresses either only capsid or prM/E instead of the entire structural polyprotein. Upon delivery to the same cell, these genomes produce together all of the viral structural proteins, and cells release a combination of virions with both types of genomes packaged into separate particles. In tissue culture, this modified YFV can be further passaged at an escalating scale by using a high multiplicity of infection (MOI). However, at a low MOI, only one of the genomes is delivered into the cells, and infection cannot spread. The replicating prM/E-encoding genome produces extracellular E protein in the form of secreted subviral particles that are known to be an effective immunogen. The presented strategy of developing viruses defective in replication might be applied to other flaviviruses, and these two-component genome viruses can be useful for diagnostic or vaccine applications, including the delivery and expression of heterologous genes. In addition, the achieved separation of the capsid-coding sequence and the cyclization signal in the YFV genome provides a new means for studying the mechanism of the flavivirus packaging process.

scholarly journals A Novel Type of Polyhedral Viruses Infecting Hyperthermophilic Archaea

2017 ◽  
Vol 91 (13) ◽  
Author(s):  
Ying Liu ◽  
Sonoko Ishino ◽  
Yoshizumi Ishino ◽  
Gérard Pehau-Arnaudet ◽  
Mart Krupovic ◽  
...  
Keyword(s):  
Genetic Material ◽  
Morphological Diversity ◽  
Open Reading Frames ◽  
Structural Proteins ◽  
Host Recognition ◽  
Hyperthermophilic Archaea ◽  
Virion Protein ◽  
Content Type ◽  
Polyhedral Particles ◽  
Isolation And Characterization

ABSTRACT Encapsidation of genetic material into polyhedral particles is one of the most common structural solutions employed by viruses infecting hosts in all three domains of life. Here, we describe a new virus of hyperthermophilic archaea, Sulfolobus polyhedral virus 1 (SPV1), which condenses its circular double-stranded DNA genome in a manner not previously observed for other known viruses. The genome complexed with virion proteins is wound up sinusoidally into a spherical coil which is surrounded by an envelope and further encased by an outer polyhedral capsid apparently composed of the 20-kDa virion protein. Lipids selectively acquired from the pool of host lipids are integral constituents of the virion. None of the major virion proteins of SPV1 show similarity to structural proteins of known viruses. However, minor structural proteins, which are predicted to mediate host recognition, are shared with other hyperthermophilic archaeal viruses infecting members of the order Sulfolobales. The SPV1 genome consists of 20,222 bp and contains 45 open reading frames, only one-fifth of which could be functionally annotated. IMPORTANCE Viruses infecting hyperthermophilic archaea display a remarkable morphological diversity, often presenting architectural solutions not employed by known viruses of bacteria and eukaryotes. Here we present the isolation and characterization of Sulfolobus polyhedral virus 1, which condenses its genome into a unique spherical coil. Due to the original genomic and architectural features of SPV1, the virus should be considered a representative of a new viral family, “Portogloboviridae.”

Sign in / Sign up

Export Citation Format

Share Document