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Viruses May 2016The Hepadnaviridae family of small, enveloped DNA viruses are characterized by a strict host range and hepatocyte tropism. The prototype hepatitis B virus (HBV) is a... (Review)
Review
The Hepadnaviridae family of small, enveloped DNA viruses are characterized by a strict host range and hepatocyte tropism. The prototype hepatitis B virus (HBV) is a major human pathogen and constitutes a public health problem, especially in high-incidence areas. Reporter-expressing recombinant viruses are powerful tools in both studies of basic virology and development of antiviral therapeutics. In addition, the highly restricted tropism of HBV for human hepatocytes makes it an ideal tool for hepatocyte-targeting in vivo applications such as liver-specific gene delivery. However, compact genome organization and complex replication mechanisms of hepadnaviruses have made it difficult to engineer replication-competent recombinant viruses that express biologically-relevant cargo genes. This review analyzes difficulties associated with recombinant hepadnavirus vector development, summarizes and compares the progress made in this field both historically and recently, and discusses future perspectives regarding both vector design and application.
Topics: Genes, Reporter; Genetic Vectors; Hepatitis B virus; Humans; Staining and Labeling; Virology
PubMed: 27171106
DOI: 10.3390/v8050125 -
Viruses Nov 2016Acquisition and transmission by an insect vector is central to the infection cycle of the majority of plant pathogenic viruses. Plant viruses can interact with their... (Review)
Review
Acquisition and transmission by an insect vector is central to the infection cycle of the majority of plant pathogenic viruses. Plant viruses can interact with their insect host in a variety of ways including both non-persistent and circulative transmission; in some cases, the latter involves virus replication in cells of the insect host. Replicating viruses can also elicit both innate and specific defense responses in the insect host. A consistent feature is that the interaction of the virus with its insect host/vector requires specific molecular interactions between virus and host, commonly via proteins. Understanding the interactions between plant viruses and their insect host can underpin approaches to protect plants from infection by interfering with virus uptake and transmission. Here, we provide a perspective focused on identifying novel approaches and research directions to facilitate control of plant viruses by better understanding and targeting virus-insect molecular interactions. We also draw parallels with molecular interactions in insect vectors of animal viruses, and consider technical advances for their control that may be more broadly applicable to plant virus vectors.
Topics: Animals; Disease Transmission, Infectious; Entomology; Host-Pathogen Interactions; Insect Vectors; Plant Diseases; Plant Viruses; Virology
PubMed: 27834855
DOI: 10.3390/v8110303 -
Current Opinion in Virology Aug 2021Bacterial communities play critical roles across all of Earth's biomes, affecting human health and global ecosystem functioning. They do so under strong constraints... (Review)
Review
Bacterial communities play critical roles across all of Earth's biomes, affecting human health and global ecosystem functioning. They do so under strong constraints exerted by viruses, that is, bacteriophages or 'phages'. Phages can reshape bacterial communities' structure, influence long-term evolution of bacterial populations, and alter host cell metabolism during infection. Metagenomics approaches, that is, shotgun sequencing of environmental DNA or RNA, recently enabled large-scale exploration of phage genomic diversity, yielding several millions of phage genomes now to be further analyzed and characterized. One major challenge however is the lack of direct host information for these phages. Several methods and tools have been proposed to bioinformatically predict the potential host(s) of uncultivated phages based only on genome sequence information. Here we review these different approaches and highlight their distinct strengths and limitations. We also outline complementary experimental assays which are being proposed to validate and refine these bioinformatic predictions.
Topics: Bacteria; Bacteriophages; Base Sequence; Computational Biology; Computer Simulation; Genes, Viral; Genome, Bacterial; Genome, Viral; Host Microbial Interactions; Host Specificity; Machine Learning; Metagenomics; Phylogeny; Viral Proteins; Virology
PubMed: 34126465
DOI: 10.1016/j.coviro.2021.05.003 -
Seminars in Diagnostic Pathology Nov 2017
Review
Topics: Biopsy; Host-Pathogen Interactions; Humans; Lung; Pneumonia, Viral; Predictive Value of Tests; Virology; Viruses
PubMed: 28693907
DOI: 10.1053/j.semdp.2017.06.005 -
Virology Journal Jan 2020Viruses 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...
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.
Topics: Animals; Cell Line; Chlorocebus aethiops; Giant Viruses; Humans; Microscopy; Students; Teaching; Teaching Materials; Vero Cells; Virology; Viruses
PubMed: 32005257
DOI: 10.1186/s12985-020-1291-9 -
ACS Infectious Diseases Mar 2018Each year there are more than 15 000 cases of human disease caused by infections with tick-borne viruses (TBVs). These illnesses occur worldwide and can range from... (Review)
Review
Each year there are more than 15 000 cases of human disease caused by infections with tick-borne viruses (TBVs). These illnesses occur worldwide and can range from very mild illness to severe encephalitis and hemorrhagic fever. Although TBVs are currently identified as neglected vector-borne pathogens and receive less attention than mosquito-borne viruses, TBVs are expanding into new regions, and infection rates are increasing. Furthermore, effective vaccines, diagnostic tools, and other countermeasures are limited. The application of contemporary technologies to TBV infections presents an excellent opportunity to develop improved, effective countermeasures. Experimental tick and mammal models of infection can be used to characterize determinants of infection, transmission, and virulence and to test candidate countermeasures. The use of ex vivo tick cultures in TBV research provides a unique way to look at infection in specific tick organs. Mammal ex vivo organ slice and, more recently, organoid cultures are additional models that can be used to elucidate direct tissue-specific responses to infection. These ex vivo model systems are convenient for testing methods involving transcript knockdown and small molecules under tightly controlled conditions. They can also be combined with in vitro and in vivo studies to tease out possible host factors and potential vaccine or therapeutic candidates. In this brief perspective, we describe how ex vivo cultures can be combined with modern technologies to advance research on TBV infections.
Topics: Animals; Encephalitis Viruses, Tick-Borne; Mammals; Models, Theoretical; Organ Culture Techniques; Virology
PubMed: 29473735
DOI: 10.1021/acsinfecdis.7b00274 -
Clinical Microbiology and Infection :... Feb 2019
Topics: Humans; Research; Virology; Virus Diseases
PubMed: 30580032
DOI: 10.1016/j.cmi.2018.12.003 -
Journal of Virology Sep 2022The existing cell culture-based methods to study hepatitis B virus (HBV) have limitations and do not allow for viral long-term passage. The aim of this study was to...
Establishment and Characterization of an HBV Viral Spread and Infectious System following Long-Term Passage of an HBV Clinical Isolate in the Primary Human Hepatocyte and Fibroblast Coculture System.
The existing cell culture-based methods to study hepatitis B virus (HBV) have limitations and do not allow for viral long-term passage. The aim of this study was to develop a robust long-term viral passage system with optimized cell culture conditions and a viral isolate with the ability to spread and passage. An HBV genotype A clinical isolate was subjected to multiple rounds of UV treatment and passaged in an optimized primary human hepatocyte (PHH)/human fibroblast coculture system. The passaged UV-treated virus was sequenced and further characterized. In addition, a panel of mutant viruses containing different combinations of mutations observed in this virus was investigated. The clinical isolate was passaged for 20 rounds with 21 days per round in an optimized PHH/human fibroblast coculture system while subject to UV mutagenesis. This passaged UV-mutated isolate harbored four mutations: G225A (sR24K) in the S gene, A2062T in the core gene, and two mutations G1764A and C1766T (xV131I) in the basal core promoter (BCP) region. characterization of the four mutations suggested that the two BCP mutations G1764A and C1766T contributed to the increased viral replication and viral infectivity. A robust long-term HBV viral passage system has been established by passaging a UV-treated clinical isolate in an optimized PHH/fibroblast coculture system. The two BCP mutations played a key role in the virus's ability to passage. This passage system can be used for studying the entire life cycle of HBV and has the potential for drug-resistance selection upon further optimization. The existing cell culture-based methods to study HBV have limitations and do not allow for viral long-term passage. In this study, an HBV genotype A clinical isolate was subjected to multiple rounds of UV treatment and passaged in an optimized PHH/human fibroblast coculture system. This passaged UV-mutated isolate carried four mutations across the HBV genome, and characterization of the four mutations suggested that the two basal core promoter (BCP) mutations G1764A and C1766T played a key role in the virus's ability to passage. In summary, we have developed a robust long-term HBV viral passage system by passaging an UV-treated HBV genotype A clinical isolate in an optimized PHH/human fibroblast coculture system. This passage system can be used for studying the entire life cycle of HBV and has the potential for drug-resistance selection upon further optimization.
Topics: Coculture Techniques; DNA, Viral; Fibroblasts; Genotype; Hepatitis B; Hepatitis B virus; Hepatocytes; Humans; Mutagenesis; Mutation; Virology; Virus Replication
PubMed: 36037476
DOI: 10.1128/jvi.00849-22 -
Cold Spring Harbor Perspectives in... Nov 2020Generally comprised of less than a dozen components, RNA viruses can be viewed as well-designed genetic circuits optimized to replicate and spread within a given host.... (Review)
Review
Generally comprised of less than a dozen components, RNA viruses can be viewed as well-designed genetic circuits optimized to replicate and spread within a given host. Understanding the molecular design that enables this activity not only allows one to disrupt these circuits to study their biology, but it provides a reprogramming framework to achieve novel outputs. Recent advances have enabled a "learning by building" approach to better understand virus biology and create valuable tools. Below is a summary of how modifying the preexisting genetic framework of influenza A virus has been used to track viral movement, understand virus replication, and identify host factors that engage this viral circuitry.
Topics: Humans; Influenza A virus; Synthetic Biology; Virology; Virus Replication
PubMed: 31871242
DOI: 10.1101/cshperspect.a038703 -
Medecine Sciences : M/S Dec 2016Unlike microbes known in his time, the first virus (that of tobacco mosaic disease) was discovered by Ivanoski in 1892 because it was not retained by Chamberland's... (Review)
Review
Unlike microbes known in his time, the first virus (that of tobacco mosaic disease) was discovered by Ivanoski in 1892 because it was not retained by Chamberland's porcelain candles. For more than a century afterward, viruses were equated with this simple property that is still extensively used today (using modern 0,2 µm pore filters) as a practical criterion to delineate the "viral fraction" from other microbes in medical or environmental samples. The first documented exception to the simplistic criterion of particle size came with the discovery of Mimivirus, the viral nature of which was eventually recognized in 2003, following ten years during which it was mistaken for an obligate intracellular bacterium. Thirteen more years later, we now realize that non-filtering "giant viruses" are not rare, probably ubiquitous, and come in a large variety of virion shapes, genome sizes, gene contents, and replication strategies. Following a quick description of the 4 giant virus families known today, we discuss the enigmas, controversies and perspectives of conceptual revolutions that are brought about by this new and booming area of virology.
Topics: Animals; Giant Viruses; History, 19th Century; History, 20th Century; History, 21st Century; Humans; Mimiviridae; Phylogeny; Virology
PubMed: 28044972
DOI: 10.1051/medsci/20163212012