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1.
J Virol ; 98(6): e0051324, 2024 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-38752754

RESUMO

Marseilleviruses (MsV) are a group of viruses that compose the Marseilleviridae family within the Nucleocytoviricota phylum. They have been found in different samples, mainly in freshwater. MsV are classically organized into five phylogenetic lineages (A/B/C/D/E), but the current taxonomy does not fully represent all the diversity of the MsV lineages. Here, we describe a novel strain isolated from a Brazilian saltwater sample named Marseillevirus cajuinensis. Based on genomics and phylogenetic analyses, M. cajuinensis exhibits a 380,653-bp genome that encodes 515 open reading frames. Additionally, M. cajuinensis encodes a transfer RNA, a feature that is rarely described for Marseilleviridae. Phylogeny suggests that M. cajuinensis forms a divergent branch within the MsV lineage A. Furthermore, our analysis suggests that the common ancestor for the five classical lineages of MsV diversified into three major groups. The organization of MsV into three main groups is reinforced by a comprehensive analysis of clusters of orthologous groups, sequence identities, and evolutionary distances considering several MsV isolates. Taken together, our results highlight the importance of discovering new viruses to expand the knowledge about known viruses that belong to the same lineages or families. This work proposes a new perspective on the Marseilleviridae lineages organization that could be helpful to a future update in the taxonomy of the Marseilleviridae family. IMPORTANCE: Marseilleviridae is a family of viruses whose members were mostly isolated from freshwater samples. In this work, we describe the first Marseillevirus isolated from saltwater samples, which we called Marseillevirus cajuinensis. Most of M. cajuinensis genomic features are comparable to other Marseilleviridae members, such as its high number of unknown proteins. On the other hand, M. cajuinensis encodes a transfer RNA, which is a gene category involved in protein translation that is rarely described in this viral family. Additionally, our phylogenetic analyses suggested the existence of, at least, three major Marseilleviridae groups. These observations provide a new perspective on Marseilleviridae lineages organization, which will be valuable in future updates to the taxonomy of the family since the current official classification does not capture all the Marseilleviridae known diversity.


Assuntos
Genoma Viral , Vírus , Brasil , Evolução Molecular , Genômica/métodos , Fases de Leitura Aberta , Filogenia , RNA Viral/genética , Vírus/classificação , Vírus/genética
2.
J Virol ; 97(2): e0182422, 2023 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-36728417

RESUMO

Among the most intriguing structural features in the known virosphere are mimivirus surface fibrils, proteinaceous filaments approximately 150 nm long, covering the mimivirus capsid surface. Fibrils are important to promote particle adhesion to host cells, triggering phagocytosis and cell infection. However, although mimiviruses are one of the most abundant viral entities in a plethora of biomes worldwide, there has been no comparative analysis on fibril organization and abundance among distinct mimivirus isolates. Here, we describe the isolation and characterization of Megavirus caiporensis, a novel lineage C mimivirus with surface fibrils organized as "clumps." This intriguing feature led us to expand our analyses to other mimivirus isolates. By employing a combined approach including electron microscopy, image processing, genomic sequencing, and viral prospection, we obtained evidence of at least three main patterns of surface fibrils that can be found in mimiviruses: (i) isolates containing particles with abundant fibrils, distributed homogeneously on the capsid surface; (ii) isolates with particles almost fibrilless; and (iii) isolates with particles containing fibrils in abundance, but organized as clumps, as observed in Megavirus caiporensis. A total of 15 mimivirus isolates were analyzed by microscopy, and their DNA polymerase subunit B genes were sequenced for phylogenetic analysis. We observed a unique match between evolutionarily-related viruses and their fibril profiles. Biological assays suggested that patterns of fibrils can influence viral entry in host cells. Our data contribute to the knowledge of mimivirus fibril organization and abundance, as well as raising questions on the evolution of those intriguing structures. IMPORTANCE Mimivirus fibrils are intriguing structures that have drawn attention since their discovery. Although still under investigation, the function of fibrils may be related to host cell adhesion. In this work, we isolated and characterized a new mimivirus, called Megavirus caiporensis, and we showed that mimivirus isolates can exhibit at least three different patterns related to fibril organization and abundance. In our study, evolutionarily-related viruses presented similar fibril profiles, and such fibrils may affect how those viruses trigger phagocytosis in amoebas. These data shed light on aspects of mimivirus particle morphology, virus-host interactions, and their evolution.


Assuntos
Mimiviridae , Proteínas do Capsídeo/genética , Genoma Viral , Microscopia Eletrônica , Mimiviridae/genética , Mimiviridae/ultraestrutura , Filogenia
3.
Arch Virol ; 169(6): 132, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38822903

RESUMO

Orpheoviruses, cedratviruses, and pithoviruses are large DNA viruses that cluster together taxonomically within the order Pimascovirales of the phylum Nucleocytoviricota. However, they were not classified previously by the International Committee on Taxonomy of Viruses (ICTV). Here, we present a comprehensive analysis of the gene content, morphology, and phylogenomics of these viruses, providing data that underpinned the recent proposal to establish new taxa for their initial classification. The new taxonomy, which has now been ratified by the ICTV, includes the family Orpheoviridae and genus Alphaorpheovirus, the family Pithoviridae and genus Alphapithovirus, and the family Cedratviridae and genus Alphacedratvirus, aiming to formally catalogue the isolates covered in this study. Additionally, as per the newly adopted rules, we applied standardized binomial names for the virus species created to classify isolates with complete genome sequences available in public databases at the time of the proposal. The specific epithet of each virus species was chosen as a reference to the location where the exemplar virus was isolated.


Assuntos
Vírus de DNA , Genoma Viral , Filogenia , Genoma Viral/genética , Vírus de DNA/genética , Vírus de DNA/classificação , DNA Viral/genética
4.
J Chem Inf Model ; 64(2): 393-411, 2024 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-38194508

RESUMO

Around three billion people are at risk of infection by the dengue virus (DENV) and potentially other flaviviruses. Worldwide outbreaks of DENV, Zika virus (ZIKV), and yellow fever virus (YFV), the lack of antiviral drugs, and limitations on vaccine usage emphasize the need for novel antiviral research. Here, we propose a consensus virtual screening approach to discover potential protease inhibitors (NS3pro) against different flavivirus. We employed an in silico combination of a hologram quantitative structure-activity relationship (HQSAR) model and molecular docking on characterized binding sites followed by molecular dynamics (MD) simulations, which filtered a data set of 7.6 million compounds to 2,775 hits. Lastly, docking and MD simulations selected six final potential NS3pro inhibitors with stable interactions along the simulations. Five compounds had their antiviral activity confirmed against ZIKV, YFV, DENV-2, and DENV-3 (ranging from 4.21 ± 0.14 to 37.51 ± 0.8 µM), displaying aggregator characteristics for enzymatic inhibition against ZIKV NS3pro (ranging from 28 ± 7 to 70 ± 7 µM). Taken together, the compounds identified in this approach may contribute to the design of promising candidates to treat different flavivirus infections.


Assuntos
Flavivirus , Pirimidinas , Infecção por Zika virus , Zika virus , Humanos , Simulação de Acoplamento Molecular , Consenso , Antivirais/química
5.
J Appl Microbiol ; 135(3)2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38373822

RESUMO

AIM: The aim of the study was to evaluate the efficiency of mimivirus as a potential therapeutic and prophylactic tool against Acanthamoeba castellanii, the etiological agent of Acanthamoeba keratitis, a progressive corneal infection, that is commonly associated with the use of contact lenses and can lead to blindness if not properly treated. METHODS AND RESULTS: Mimivirus particles were tested in different multiplicity of infection, along with commercial multipurpose contact lenses' solutions, aiming to assess their ability to prevent encystment and excystment of A. castellanii. Solutions were evaluated for their amoebicidal potential and cytotoxicity in MDCK cells, as well as their effectiveness in preventing A. castellanii damage in Madin-Darby canine kidney (MDCK) cells. Results indicated that mimivirus was able to inhibit the formation of A. castellanii cysts, even in the presence of Neff encystment solution. Mimivirus also showed greater effectiveness in controlling A. castellanii excystment compared to commercial solutions. Additionally, mimivirus solution was more effective in preventing damage caused by A. castellanii, presented greater amoebicidal activity, and were less cytotoxic to MDCK cells than commercial MPS. CONCLUSIONS: Mimivirus demonstrates a greater ability to inhibit A. castellanii encystment and excystment compared to commercial multipurpose contact lens solutions. Additionally, mimivirus is less toxic to MDCK cells than those commercial solutions. New studies utilizing in vivo models will be crucial for confirming safety and efficacy parameters.


Assuntos
Amebíase , Vírus Gigantes , Animais , Cães , Biotecnologia
6.
J Med Virol ; 95(2): e28536, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36708101

RESUMO

In early May 2022, the first worldwide monkeypox virus (MPXV) outbreak was reported, with different clinical aspects from previously studied human monkeypox infections. Despite monkeypox medical importance, much of its biological aspects remain to be further investigated. In the present work, we evaluated ultrastructural aspects of MPXV asynchronous infections in Vero cells by transmission electron microscopy (TEM). The viral strain was isolated from a male patient infected during the 2022 outbreak. TEM analysis showed: (i) adhered intracellular mature virus particles before entry of the host cell; (ii) a reorganization of the rough endoplasmic reticulum cisternae into the so-called "mini-nuclei" structure associated with genome replication; and (iii) noticeably different sites within the viral factory presenting granular or fibrillar aspects. We also observed viral crescents, different MPXV particle morphotypes, and cellular alterations induced by infection, such as changes in the cytoskeleton structure and multimembrane vesicles abundance. Taken together, to the best of our knowledge, these results revealed for the first-time ultrastructural aspects of different steps of the MPXV cycle.


Assuntos
Mpox , Animais , Chlorocebus aethiops , Masculino , Humanos , Células Vero , Monkeypox virus/genética , Replicação Viral
7.
Arch Virol ; 167(2): 711-715, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35000005

RESUMO

Here, we propose the creation of the family "Yaraviridae", a new taxon to classify a virus infecting Acanthamoeba castellanii cells. Recently, we described the discovery of a new virus infecting free-living amoebae, yaravirus, which has features that strongly differ from those of all other viruses of amoebae described to date. Yaravirus particles are about 80 nm in diameter and have a dsDNA genome of ~45 kbp containing 74 ORFs, most of which (>90%) have no homologs in current databases. Together, these data support the creation of a new species ("Yaravirus brasiliense"), a new viral genus (here proposed as "Yaravirus"), and a new viral family (here proposed as "Yaraviridae") to classify yaravirus and other related viruses that may be described in the future. All of them are to be included into the existing realm Varidnaviria and the kingdom Bamfordvirae, due to the presence of a major capsid protein containing a double jelly-roll fold.


Assuntos
Acanthamoeba castellanii , Proteínas do Capsídeo , Vírus de DNA/genética , Genoma Viral
8.
Environ Res ; 195: 110808, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33513382

RESUMO

Although much has been discovered regarding the characteristics of SARS-CoV-2, its presence in aerosols and their implications in the context of the pandemic is still controversial. More research on this topic is needed to contribute to these discussions. Presented herein are the results of ongoing research to detect SARS-CoV-2 RNA in aerosol in different hospital facilities (indoor environments) and public spaces (outdoor environments) of a metropolitan center in Brazil. From May to August 2020, 62 samples were collected using active sampling method (air samplers with filters) and passive method (petri dishes) in two hospitals, with different occupancies and infrastructure for contamination control. Outdoor public spaces such as sidewalks and a bus station were also investigated. Five air samples from four facilities in a hospital tested positive for SARS-CoV-2 in suspended and sedimentable particles. SARS-CoV-2 was found in aerosols inside the Intensive Care Unit (ICU), in the protective apparel removal room, in the room containing patient mobile toilets and used clothes (room with natural ventilation) and in an external corridor adjacent to the ICU, probably coming from infected patients and/or from aerosolization of virus-laden particles on material/equipment. Our findings reinforce the hypothesis of airborne transmission of the new coronavirus, contributing to the planning of effective practices for pandemic control.


Assuntos
COVID-19 , SARS-CoV-2 , Aerossóis , Brasil , Hospitais , Humanos , RNA Viral
9.
J Virol ; 93(14)2019 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-31019058

RESUMO

Viruses depend on cells to replicate and can cause considerable damage to their hosts. However, hosts have developed a plethora of antiviral mechanisms to counterattack or prevent viral replication and to maintain homeostasis. Advantageous features are constantly being selected, affecting host-virus interactions and constituting a harsh race for supremacy in nature. Here, we describe a new antiviral mechanism unveiled by the interaction between a giant virus and its amoebal host. Faustovirus mariensis infects Vermamoeba vermiformis, a free-living amoeba, and induces cell lysis to disseminate into the environment. Once infected, the cells release a soluble factor that triggers the encystment of neighbor cells, preventing their infection. Remarkably, infected cells stimulated by the factor encyst and trap the viruses and viral factories inside cyst walls, which are no longer viable and cannot excyst. This unprecedented mechanism illustrates that a plethora of antiviral strategies remains to be discovered in nature.IMPORTANCE Understanding how viruses of microbes interact with its hosts is not only important from a basic scientific point of view but also for a better comprehension of the evolution of life. Studies involving large and giant viruses have revealed original and outstanding mechanisms concerning virus-host relationships. Here, we report a mechanism developed by Vermamoeba vermiformis, a free-living amoeba, to reduce Faustovirus mariensis dissemination. Once infected, V. vermiformis cells release a factor that induces the encystment of neighbor cells, preventing infection of further cells and/or trapping the viruses and viral factories inside the cyst walls. This phenomenon reinforces the need for more studies regarding large/giant viruses and their hosts.


Assuntos
Amebozoários/virologia , Vírus Gigantes/fisiologia , Replicação Viral/fisiologia , Vírus não Classificados/fisiologia
10.
J Virol ; 93(5)2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30541841

RESUMO

Giant viruses are complex members of the virosphere, exhibiting outstanding structural and genomic features. Among these viruses, the pandoraviruses are some of the most intriguing members, exhibiting giant particles and genomes presenting at up to 2.5 Mb, with many genes having no known function. In this work, we analyzed, by virological and microscopic methods, the replication cycle steps of three new pandoravirus isolates from samples collected in different regions of Brazil. Our data indicate that all analyzed pandoravirus isolates can deeply modify the Acanthamoeba cytoplasmic environment, recruiting mitochondria and membranes into and around the electron-lucent viral factories. We also observed that the viral factories start forming before the complete degradation of the cellular nucleus. Various patterns of pandoravirus particle morphogenesis were observed, and the assembly of the particles seemed to be started either by the apex or by the opposite side. On the basis of the counting of viral particles during the infection time course, we observed that pandoravirus particles could undergo exocytosis after their morphogenesis in a process that involved intense recruitment of membranes that wrapped the just-formed particles. The treatment of infected cells with brefeldin affected particle exocytosis in two of the three analyzed strains, indicating biological variability among isolates. Despite such particle exocytosis, the lysis of host cells also contributed to viral release. This work reinforces knowledge of and reveals important steps in the replication cycle of pandoraviruses.IMPORTANCE The emerging Pandoraviridae family is composed of some of the most complex viruses known to date. Only a few pandoravirus isolates have been described until now, and many aspects of their life cycle remain to be elucidated. A comprehensive description of the replication cycle is pivotal to a better understanding of the biology of the virus. For this report, we describe new pandoraviruses and used different methods to better characterize the steps of the replication cycle of this new group of viruses. Our results provide new information about the diversity and biology of these giant viruses.


Assuntos
Acanthamoeba castellanii/virologia , Vírus de DNA/genética , Liberação de Vírus/fisiologia , Replicação Viral/fisiologia , Brasil , Vírus de DNA/isolamento & purificação , Genoma Viral/genética , Vírus Gigantes/genética , Vírus Gigantes/isolamento & purificação
11.
Virol J ; 17(1): 13, 2020 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-32005257

RESUMO

BACKGROUND: Viruses are the most numerous entities on Earth and have also been central to many episodes in the history of humankind. As the study of viruses progresses further and further, there are several limitations in transferring this knowledge to undergraduate and high school students. This deficiency is due to the difficulty in designing hands-on lessons that allow students to better absorb content, given limited financial resources and facilities, as well as the difficulty of exploiting viral particles, due to their small dimensions. The development of tools for teaching virology is important to encourage educators to expand on the covered topics and connect them to recent findings. Discoveries, such as giant DNA viruses, have provided an opportunity to explore aspects of viral particles in ways never seen before. Coupling these novel findings with techniques already explored by classical virology, including visualization of cytopathic effects on permissive cells, may represent a new way for teaching virology. This work aimed to develop a slide microscope kit that explores giant virus particles and some aspects of animal virus interaction with cell lines, with the goal of providing an innovative approach to virology teaching. METHODS: Slides were produced by staining, with crystal violet, purified giant viruses and BSC-40 and Vero cells infected with viruses of the genera Orthopoxvirus, Flavivirus, and Alphavirus. Slides with amoebae infected with different species of giant viruses and stained with hemacolor reagents were also produced. RESULTS: Staining of the giant viruses allowed better visualization of the viral particles, and this technique highlights the diversity in morphology and sizes among them. Hemacolor staining enabled visualization of viral factories in amoebae, and the staining of infected BSC-40 and Vero cell monolayers with crystal violet highlights plaque-forming units. CONCLUSIONS: This kit was used in practical virology classes for the Biological Sciences course (UFMG, Brazil), and it will soon be made available at a low-cost for elementary school teachers in institutions that have microscopes. We hope this tool will foster an inspiring learning environment.


Assuntos
Materiais de Ensino , Ensino , Virologia/educação , Vírus , Animais , Linhagem Celular , Chlorocebus aethiops , Vírus Gigantes/fisiologia , Humanos , Microscopia/instrumentação , Estudantes , Células Vero
12.
Arch Virol ; 165(6): 1267-1278, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32333117

RESUMO

Giant viruses of amoebas are a remarkable group of viruses. In addition to their large size and peculiar structures, the genetic content of these viruses is also special. Among the genetic features of these viruses that stand out is the presence of coding regions for elements involved in translation, a complex biological process that occurs in cellular organisms. No viral genome described so far has such a complex genetic arsenal as those of giant viruses, which code for several of these elements. Currently, tupanviruses have the most complete set of translation genes in the known virosphere. In this review, we have condensed what is currently known about translation genes in different groups of giant viruses and theorize about their biological importance, origin, and evolution, and what might possibly be found in the coming years.


Assuntos
Vírus Gigantes/genética , Mimiviridae/genética , Amoeba/virologia , Evolução Molecular , Genoma Viral , Vírus Gigantes/patogenicidade , Especificidade de Hospedeiro/genética , Mimiviridae/metabolismo , Mimiviridae/ultraestrutura , Filogenia , Biossíntese de Proteínas , Proteoma/genética , RNA Ribossômico 16S/genética , RNA Viral/genética
13.
Arch Virol ; 165(4): 853-863, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32052196

RESUMO

Since its discovery, the first identified giant virus associated with amoebae, Acanthamoeba polyphaga mimivirus (APMV), has been rigorously studied to understand the structural and genomic complexity of this virus. In this work, we report the isolation and genomic characterization of a new mimivirus of lineage B, named "Borely moumouvirus". This new virus exhibits a structure and replicative cycle similar to those of other members of the family Mimiviridae. The genome of the new isolate is a linear double-strand DNA molecule of ~1.0 Mb, containing over 900 open reading frames. Genome annotation highlighted different translation system components encoded in the DNA of Borely moumouvirus, including aminoacyl-tRNA synthetases, translation factors, and tRNA molecules, in a distribution similar to that in other lineage B mimiviruses. Pan-genome analysis indicated an increase in the genetic arsenal of this group of viruses, showing that the family Mimiviridae is still expanding. Furthermore, phylogenetic analysis has shown that Borely moumouvirus is closely related to moumouvirus australiensis. This is the first mimivirus lineage B isolated from Brazilian territory to be characterized. Further prospecting studies are necessary for us to better understand the diversity of these viruses so a better classification system can be established.


Assuntos
Genoma Viral , Mimiviridae/isolamento & purificação , Rios/virologia , Brasil , Genômica , Mimiviridae/classificação , Mimiviridae/genética , Mimiviridae/fisiologia , Filogenia , Replicação Viral
14.
PLoS Genet ; 13(2): e1006532, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-28207761

RESUMO

The giant mimiviruses challenged the well-established concept of viruses, blurring the roots of the tree of life, mainly due to their genetic content. Along with other nucleo-cytoplasmic large DNA viruses, they compose a new proposed order-named Megavirales-whose origin and evolution generate heated debate in the scientific community. The presence of an arsenal of genes not widespread in the virosphere related to important steps of the translational process, including transfer RNAs, aminoacyl-tRNA synthetases, and translation factors for peptide synthesis, constitutes an important element of this debate. In this review, we highlight the main findings to date about the translational machinery of the mimiviruses and compare their distribution along the distinct members of the family Mimiviridae. Furthermore, we discuss how the presence and/or absence of the translation-related genes among mimiviruses raises important insights to boost the debate on their origin and evolutionary history.


Assuntos
Evolução Molecular , Mimiviridae/genética , Biossíntese de Proteínas , RNA de Transferência/genética , Aminoacil-tRNA Sintetases/genética , Núcleo Celular/genética , Citoplasma , Vírus de DNA/genética , Filogenia
15.
Parasitol Res ; 119(2): 659-666, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31848745

RESUMO

Free-living amoebae of the genus Acanthamoeba are causative agents of Acanthamoeba keratitis and amoebic encephalitis in humans, both of which are serious infections. The ability to produce proteases is one of the factors involved in the pathogenesis of Acanthamoeba infections. The aim of this study was to evaluate the secreted proteases of six Acanthamoeba strains from distinct genotypes (T1, T2, T4 and T11) maintained in prolonged axenic culture and following three successive passages in Madin-Darby Canine Kidney (MDCK) cells. Conditioned medium was obtained from cultures before and after interaction with the MDCK monolayers, resolved in SDS-PAGE containing gelatine, then subjected to quantitative azocasein assays. Zymography profiles varied between the strains, with the predominant proteases found to be serine-type proteases from 49 to 128 kDa. A T1 genotype strain isolated from dust showed quantitatively higher protease secretion compared to the other strains. No changes were detected in the zymography profiles of MDCK-interacted cultures compared to long-term axenic cultures. Two strains presented lower proteolytic activity post-MDCK interaction, while the remaining strains presented similar values before and after MDCK passages. In conclusion, this study confirms the predominance of serine-type protease secretion by Acanthamoeba, with distinct profiles presented by the different strains and genotypes studied. Also, interaction of trophozoites with MDCK cells did not alter the zymography pattern.


Assuntos
Acanthamoeba/enzimologia , Acanthamoeba/metabolismo , Serina Proteases/metabolismo , Acanthamoeba/genética , Ceratite por Acanthamoeba/parasitologia , Animais , Cultura Axênica , Caseínas/análise , Linhagem Celular , Cães , Genótipo , Humanos , Células Madin Darby de Rim Canino , Trofozoítos/metabolismo
16.
J Virol ; 92(2)2018 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-29118120

RESUMO

The inclusion of Mimiviridae members in the putative monophyletic nucleocytoplasmic large DNA virus (NCLDV) group is based on genomic and phylogenomic patterns. This shows that, along with other viral families, they share a set of genes known as core or "hallmark genes," including the gene for the major capsid protein (MCP). Although previous studies have suggested that the maturation of mimivirus MCP transcripts is dependent on splicing, there is little information about the processing of this transcript in other mimivirus isolates. Here we report the characterization of a new mimivirus isolate, called Kroon virus (KV) mimivirus. Analysis of the structure, synteny, and phylogenetic relationships of the MCP genes in many mimivirus isolates revealed a remarkable variation at position and types of intronic and exonic regions, even for mimiviruses belonging to the same lineage. In addition, sequencing of KV and Acanthamoeba polyphaga mimivirus (APMV) MCP transcripts has shown that inside the family, even related giant viruses may present different ways to process the MCP mRNA. These results contribute to the understanding of the genetic organization and evolution of the MCP gene in mimiviruses.IMPORTANCE Mimivirus isolates have been obtained by prospecting studies since 2003. Based on genomic and phylogenomic studies of conserved genes, these viruses have been clustered together with members of six other viral families. Although the major capsid protein (MCP) gene is an important member of the so-called "hallmark genes," there is little information about the processing and structure of this gene in many mimivirus isolates. In this work, we have analyzed the structure, synteny, and phylogenetic relationships of the MCP genes in many mimivirus isolates; these genes showed remarkable variation at position and types of intronic and exonic regions, even for mimiviruses belonging to the same lineage. These results contribute to the understanding of the genetic organization and evolution of the MCP gene in mimiviruses.


Assuntos
Proteínas do Capsídeo/genética , Evolução Molecular , Regulação Viral da Expressão Gênica , Mimiviridae/genética , Splicing de RNA , Transcrição Gênica , Genoma Viral , Mimiviridae/classificação , Mimiviridae/isolamento & purificação , Mimiviridae/ultraestrutura , Filogenia , RNA Viral , Replicação Viral , Microbiologia da Água
17.
J Virol ; 92(13)2018 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-29695424

RESUMO

Giant viruses have been isolated and characterized in different environments, expanding our knowledge about the biology of these unique microorganisms. In the last 2 years, a new group was discovered, the cedratviruses, currently composed of only two isolates and members of a putative new family, "Pithoviridae," along with previously known pithoviruses. Here we report the isolation and biological and genomic characterization of two novel cedratviruses isolated from samples collected in France and Brazil. Both viruses were isolated using Acanthamoeba castellanii as a host cell and exhibit ovoid particles with corks at either extremity of the particle. Curiously, the Brazilian cedratvirus is ∼20% smaller and presents a shorter genome of 460,038 bp, coding for fewer proteins than other cedratviruses. In addition, it has a completely asyntenic genome and presents a lower amino acid identity of orthologous genes (∼73%). Pangenome analysis comprising the four cedratviruses revealed an increase in the pangenome concomitant with a decrease in the core genome with the addition of the two novel viruses. Finally, phylogenetic analyses clustered the Brazilian virus in a separate branch within the group of cedratviruses, while the French isolate is closer to the previously reported Cedratvirus lausannensis Taking all together, we propose the existence of a second lineage of this emerging viral genus and provide new insights into the biodiversity and ubiquity of these giant viruses.IMPORTANCE Various giant viruses have been described in recent years, revealing a unique part of the virosphere. A new group among the giant viruses has recently been described, the cedratviruses, which is currently composed of only two isolates. In this paper, we describe two novel cedratviruses isolated from French and Brazilian samples. Biological and genomic analyses showed viruses with different particle sizes, genome lengths, and architecture, revealing the existence of a second lineage of this new group of giant viruses. Our results provide new insights into the biodiversity of cedratviruses and highlight the importance of ongoing efforts to prospect for and characterize new giant viruses.


Assuntos
Acanthamoeba castellanii/virologia , Evolução Molecular , Genoma Viral , Genômica/métodos , Vírus Gigantes/classificação , Vírus Gigantes/genética , Vírion/genética , DNA Viral , Filogenia , Análise de Sequência de DNA/métodos
18.
Arch Virol ; 164(1): 325-331, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30291500

RESUMO

The genus "Tupanvirus" is a new proposed taxon to be included in the family Mimiviridae. The two known tupanvirus isolates were isolated from soda lake and oceanic sediments samples collected in Brazil and were named "tupanvirus soda lake" and "tupanvirus deep ocean", respectively. These viruses exhibit similarities to amoeba-infecting mimiviruses, but there are also several differences that place them in a separate group within the family Mimiviridae. Their virions have a mean size of 1.2 µm, which include a mimivirus-like capsid and a large cylindrical tail, both covered by fibrils. The linear double-stranded DNA genomes of up to 1,516,267 base pairs encode over 1,200 genes, among which ~ 30% have no homologs in any database, including in other mimivirus genomes. Compared to other mimiviruses, tupanviruses exhibit a broader host range and cause a cytotoxic effect in host and non-host organisms, a phenotype that is not observed for other mimiviruses. Remarkably, these viruses possess the most complete gene set related to the protein synthesis process, including 20 aminoacyl-tRNA synthetases, 67-70 tRNAs, many translation factors, and genes involved in maturation and modification of tRNA and mRNA, among others. Moreover, diverse phylogenomic analyses put tupanviruses in a distinct group within the family Mimiviridae. In light of the set of different features observed for these giant viruses, we propose establishment of a new genus to allow proper classification of two known tupanviruses and possibly many more similar viruses yet to be characterized.


Assuntos
Mimiviridae/classificação , Mimiviridae/genética , Amoeba/virologia , DNA Viral , Regulação Viral da Expressão Gênica , Genoma Viral , Genômica , Filogenia , Proteoma
19.
Emerg Infect Dis ; 24(1): 161-162, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29260673

RESUMO

We studied a clinical case of vaccinia virus that caused an ocular manifestation in a dairy worker in Brazil. Biologic and molecular analyses identified a co-infection with 2 isolates from different Brazilian vaccinia virus phylogenetic groups.


Assuntos
Indústria de Laticínios , Oftalmopatias/virologia , Vaccinia virus/isolamento & purificação , Vacínia/epidemiologia , Vacínia/virologia , Animais , Brasil/epidemiologia , Bovinos , Genoma Viral , Humanos , Masculino , Pessoa de Meia-Idade , Exposição Ocupacional , Filogenia , Vaccinia virus/genética
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