Viruses

24 pages, 1121 KiB

Open AccessReview

Drug Repositioning: New Approaches and Future Prospects for Life-Debilitating Diseases and the COVID-19 Pandemic Outbreak

by Zheng Yao Low, Isra Ahmad Farouk and Sunil Kumar Lal

Viruses 2020, 12(9), 1058; https://doi.org/10.3390/v12091058 - 22 Sep 2020

Cited by 98 | Viewed by 8944

Abstract

Traditionally, drug discovery utilises a de novo design approach, which requires high cost and many years of drug development before it reaches the market. Novel drug development does not always account for orphan diseases, which have low demand and hence low-profit margins for [...] Read more.

Traditionally, drug discovery utilises a de novo design approach, which requires high cost and many years of drug development before it reaches the market. Novel drug development does not always account for orphan diseases, which have low demand and hence low-profit margins for drug developers. Recently, drug repositioning has gained recognition as an alternative approach that explores new avenues for pre-existing commercially approved or rejected drugs to treat diseases aside from the intended ones. Drug repositioning results in lower overall developmental expenses and risk assessments, as the efficacy and safety of the original drug have already been well accessed and approved by regulatory authorities. The greatest advantage of drug repositioning is that it breathes new life into the novel, rare, orphan, and resistant diseases, such as Cushing’s syndrome, HIV infection, and pandemic outbreaks such as COVID-19. Repositioning existing drugs such as Hydroxychloroquine, Remdesivir, Ivermectin and Baricitinib shows good potential for COVID-19 treatment. This can crucially aid in resolving outbreaks in urgent times of need. This review discusses the past success in drug repositioning, the current technological advancement in the field, drug repositioning for personalised medicine and the ongoing research on newly emerging drugs under consideration for the COVID-19 treatment. Full article

(This article belongs to the Special Issue Drug-Repositioning Opportunities for Antiviral Therapy)

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18 pages, 2210 KiB

Open AccessArticle

An Unconventional Flavivirus and Other RNA Viruses in the Sea Cucumber (Holothuroidea; Echinodermata) Virome

by Ian Hewson, Mitchell R. Johnson and Ian R. Tibbetts

Viruses 2020, 12(9), 1057; https://doi.org/10.3390/v12091057 - 22 Sep 2020

Cited by 13 | Viewed by 5110

Abstract

Sea cucumbers (Holothuroidea; Echinodermata) are ecologically significant constituents of benthic marine habitats. We surveilled RNA viruses inhabiting eight species (representing four families) of holothurian collected from four geographically distinct locations by viral metagenomics, including a single specimen of Apostichopus californicus affected by a [...] Read more.

Sea cucumbers (Holothuroidea; Echinodermata) are ecologically significant constituents of benthic marine habitats. We surveilled RNA viruses inhabiting eight species (representing four families) of holothurian collected from four geographically distinct locations by viral metagenomics, including a single specimen of Apostichopus californicus affected by a hitherto undocumented wasting disease. The RNA virome comprised genome fragments of both single-stranded positive sense and double stranded RNA viruses, including those assigned to the Picornavirales, Ghabrivirales, and Amarillovirales. We discovered an unconventional flavivirus genome fragment which was most similar to a shark virus. Ghabivirales-like genome fragments were most similar to fungal totiviruses in both genome architecture and homology and had likely infected mycobiome constituents. Picornavirales, which are commonly retrieved in host-associated viral metagenomes, were similar to invertebrate transcriptome-derived picorna-like viruses. The greatest number of viral genome fragments was recovered from the wasting A. californicus library compared to the asymptomatic A. californicus library. However, reads from the asymptomatic library recruited to nearly all recovered wasting genome fragments, suggesting that they were present but not well represented in the grossly normal specimen. These results expand the known host range of flaviviruses and suggest that fungi and their viruses may play a role in holothurian ecology. Full article

(This article belongs to the Collection Unconventional Viruses)

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23 pages, 7699 KiB

Open AccessArticle

A Unique Relative of Rotifer Birnavirus Isolated from Australian Mosquitoes

by Caitlin A. O’Brien, Cassandra L. Pegg, Amanda S. Nouwens, Helle Bielefeldt-Ohmann, Bixing Huang, David Warrilow, Jessica J. Harrison, John Haniotis, Benjamin L. Schulz, Devina Paramitha, Agathe M. G. Colmant, Natalee D. Newton, Stephen L. Doggett, Daniel Watterson, Jody Hobson-Peters and Roy A. Hall

Viruses 2020, 12(9), 1056; https://doi.org/10.3390/v12091056 - 22 Sep 2020

Cited by 9 | Viewed by 4054

Abstract

The family Birnaviridae are a group of non-enveloped double-stranded RNA viruses which infect poultry, aquatic animals and insects. This family includes agriculturally important pathogens of poultry and fish. Recently, next-generation sequencing technologies have identified closely related birnaviruses in Culex, Aedes and Anopheles mosquitoes. [...] Read more.

The family Birnaviridae are a group of non-enveloped double-stranded RNA viruses which infect poultry, aquatic animals and insects. This family includes agriculturally important pathogens of poultry and fish. Recently, next-generation sequencing technologies have identified closely related birnaviruses in Culex, Aedes and Anopheles mosquitoes. Using a broad-spectrum system based on detection of long double-stranded RNA, we have discovered and isolated a birnavirus from Aedes notoscriptus mosquitoes collected in northern New South Wales, Australia. Phylogenetic analysis of Aedes birnavirus (ABV) showed that it is related to Rotifer birnavirus, a pathogen of microscopic aquatic animals. In vitro cell infection assays revealed that while ABV can replicate in Aedes-derived cell lines, the virus does not replicate in vertebrate cells and displays only limited replication in Culex- and Anopheles-derived cells. A combination of SDS-PAGE and mass spectrometry analysis suggested that the ABV capsid precursor protein (pVP2) is larger than that of other birnaviruses and is partially resistant to trypsin digestion. Reactivity patterns of ABV-specific polyclonal and monoclonal antibodies indicate that the neutralizing epitopes of ABV are SDS sensitive. Our characterization shows that ABV displays a number of properties making it a unique member of the Birnaviridae and represents the first birnavirus to be isolated from Australian mosquitoes. Full article

(This article belongs to the Special Issue Mosquito-Specific Viruses: Their Role in Nature and Potential Use for Vector Control or Control of Arboviral Pathogens)

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16 pages, 4373 KiB

Open AccessArticle

The Epidemiological Signature of Pathogen Populations That Vary in the Relationship between Free-Living Parasite Survival and Virulence

by Lourdes M. Gomez, Victor A. Meszaros, Wendy C. Turner and C. Brandon Ogbunugafor

Viruses 2020, 12(9), 1055; https://doi.org/10.3390/v12091055 - 22 Sep 2020

Cited by 5 | Viewed by 3854

Abstract

The relationship between parasite virulence and transmission is a pillar of evolutionary theory that has implications for public health. Part of this canon involves the idea that virulence and free-living survival (a key component of transmission) may have different relationships in different host–parasite [...] Read more.

The relationship between parasite virulence and transmission is a pillar of evolutionary theory that has implications for public health. Part of this canon involves the idea that virulence and free-living survival (a key component of transmission) may have different relationships in different host–parasite systems. Most examinations of the evolution of virulence-transmission relationships—Theoretical or empirical in nature—Tend to focus on the evolution of virulence, with transmission being a secondary consideration. Even within transmission studies, the focus on free-living survival is a smaller subset, though recent studies have examined its importance in the ecology of infectious diseases. Few studies have examined the epidemic-scale consequences of variation in survival across different virulence–survival relationships. In this study, we utilize a mathematical model motivated by aspects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) natural history to investigate how evolutionary changes in survival may influence several aspects of disease dynamics at the epidemiological scale. Across virulence–survival relationships (where these traits are either positively or negatively correlated), we found that small changes (5% above and below the nominal value) in survival can have a meaningful effect on certain outbreak features, including R₀, and on the size of the infectious peak in the population. These results highlight the importance of properly understanding the mechanistic relationship between virulence and parasite survival, as the evolution of increased survival across different relationships with virulence may have considerably different epidemiological signatures. Full article

(This article belongs to the Special Issue Virus Ecology and Evolution: Current Research and Future Directions)

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13 pages, 2477 KiB

Open AccessArticle

Identification of a Membrane Binding Peptide in the Envelope Protein of MHV Coronavirus

by Entedar A. J. Alsaadi, Benjamin W. Neuman and Ian M. Jones

Viruses 2020, 12(9), 1054; https://doi.org/10.3390/v12091054 - 22 Sep 2020

Cited by 9 | Viewed by 5187

Abstract

Coronaviruses (CoVs) are enveloped, positive sense, single strand RNA viruses that cause respiratory, intestinal and neurological diseases in mammals and birds. Following replication, CoVs assemble on intracellular membranes including the endoplasmic reticulum Golgi intermediate compartment (ERGIC) where the envelope protein (E) functions in [...] Read more.

Coronaviruses (CoVs) are enveloped, positive sense, single strand RNA viruses that cause respiratory, intestinal and neurological diseases in mammals and birds. Following replication, CoVs assemble on intracellular membranes including the endoplasmic reticulum Golgi intermediate compartment (ERGIC) where the envelope protein (E) functions in virus assembly and release. In consequence, E potentially contains membrane-modifying peptides. To search for such peptides, the E coding sequence of Mouse Hepatitis Virus (MHV) was inspected for its amino acid conservation, proximity to the membrane and/or predicted amphipathic helices. Peptides identified in silico were synthesized and tested for membrane-modifying activity in the presence of giant unilamellar vesicles (GUVs) consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), sphingomyelin and cholesterol. To confirm the presence of membrane binding peptides identified in the context of a full-length E protein, the wild type and a number of mutants in the putative membrane binding peptide were expressed in Lenti-X-293T mammalian and insect cells, and the distribution of E antigen within the expressing cell was assessed. Our data identify a role for the post-transmembrane region of MHV E in membrane binding. Full article

(This article belongs to the Collection Coronaviruses)

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18 pages, 4696 KiB

Open AccessReview

Structural Biology of Influenza Hemagglutinin: An Amaranthine Adventure

by Nicholas C. Wu and Ian A. Wilson

Viruses 2020, 12(9), 1053; https://doi.org/10.3390/v12091053 - 22 Sep 2020

Cited by 38 | Viewed by 7165

Abstract

Hemagglutinin (HA) glycoprotein is an important focus of influenza research due to its role in antigenic drift and shift, as well as its receptor binding and membrane fusion functions, which are indispensable for viral entry. Over the past four decades, X-ray crystallography has [...] Read more.

Hemagglutinin (HA) glycoprotein is an important focus of influenza research due to its role in antigenic drift and shift, as well as its receptor binding and membrane fusion functions, which are indispensable for viral entry. Over the past four decades, X-ray crystallography has greatly facilitated our understanding of HA receptor binding, membrane fusion, and antigenicity. The recent advances in cryo-EM have further deepened our comprehension of HA biology. Since influenza HA constantly evolves in natural circulating strains, there are always new questions to be answered. The incessant accumulation of knowledge on the structural biology of HA over several decades has also facilitated the design and development of novel therapeutics and vaccines. This review describes the current status of the field of HA structural biology, how we got here, and what the next steps might be. Full article

(This article belongs to the Special Issue In Memory of Michael Rossmann)

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16 pages, 3728 KiB

Open AccessArticle

Characterization of PlyB221 and PlyP32, Two Novel Endolysins Encoded by Phages Preying on the Bacillus cereus Group

by Audrey Leprince, Manon Nuytten, Annika Gillis and Jacques Mahillon

Viruses 2020, 12(9), 1052; https://doi.org/10.3390/v12091052 - 21 Sep 2020

Cited by 12 | Viewed by 3626

Abstract

Endolysins are phage-encoded enzymes implicated in the breaching of the bacterial cell wall at the end of the viral cycle. This study focuses on the endolysins of Deep-Blue (PlyB221) and Deep-Purple (PlyP32), two phages preying on the Bacillus cereus group. Both enzymes exhibit [...] Read more.

Endolysins are phage-encoded enzymes implicated in the breaching of the bacterial cell wall at the end of the viral cycle. This study focuses on the endolysins of Deep-Blue (PlyB221) and Deep-Purple (PlyP32), two phages preying on the Bacillus cereus group. Both enzymes exhibit a typical modular organization with an enzymatically active domain (EAD) located in the N-terminal and a cell wall binding domain (CBD) in the C-terminal part of the protein. In silico analysis indicated that the EAD domains of PlyB221 and PlyP32 are endowed with peptidase and muramidase activities, respectively, whereas in both proteins SH3 domains are involved in the CBD. To evaluate their antimicrobial properties and binding specificity, both endolysins were expressed and purified. PlyB221 and PlyP32 efficiently recognized and lysed all the tested strains from the B. cereus group. Biochemical characterization showed that PlyB221 activity was stable under a wide range of pHs (5–9), NaCl concentrations (up to 200 mM), and temperature treatments (up to 50 °C). Although PlyP32 activity was less stable than that of PlyB221, the endolysin displayed high activity at pH 6–7, NaCl concentration up to 100 mM and the temperature treatment up to 45 °C. Overall, PlyB221 and PlyP32 display suitable characteristics for the development of biocontrol and detection tools. Full article

(This article belongs to the Section Bacterial Viruses)

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Graphical abstract

23 pages, 704 KiB

Open AccessReview

Immune Checkpoints in Viral Infections

by Huiming Cai, Ge Liu, Jianfeng Zhong, Kai Zheng, Haitao Xiao, Chenyang Li, Xun Song, Ying Li, Chenshu Xu, Haiqiang Wu, Zhendan He and Qinchang Zhu

Viruses 2020, 12(9), 1051; https://doi.org/10.3390/v12091051 - 21 Sep 2020

Cited by 43 | Viewed by 4561

Abstract

As evidence has mounted that virus-infected cells, such as cancer cells, negatively regulate the function of T-cells via immune checkpoints, it has become increasingly clear that viral infections similarly exploit immune checkpoints as an immune system escape mechanism. Although immune checkpoint therapy has [...] Read more.

As evidence has mounted that virus-infected cells, such as cancer cells, negatively regulate the function of T-cells via immune checkpoints, it has become increasingly clear that viral infections similarly exploit immune checkpoints as an immune system escape mechanism. Although immune checkpoint therapy has been successfully used in cancer treatment, numerous studies have suggested that such therapy may also be highly relevant for treating viral infection, especially chronic viral infections. However, it has not yet been applied in this manner. Here, we reviewed recent findings regarding immune checkpoints in viral infections, including COVID-19, and discussed the role of immune checkpoints in different viral infections, as well as the potential for applying immune checkpoint blockades as antiviral therapy. Full article

(This article belongs to the Section Animal Viruses)

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15 pages, 3376 KiB

Open AccessArticle

Metagenomic Insights into the Sewage RNA Virosphere of a Large City

by Sergio Guajardo-Leiva, Jonás Chnaiderman, Aldo Gaggero and Beatriz Díez

Viruses 2020, 12(9), 1050; https://doi.org/10.3390/v12091050 - 21 Sep 2020

Cited by 24 | Viewed by 4771

Abstract

Sewage-associated viruses can cause several human and animal diseases, such as gastroenteritis, hepatitis, and respiratory infections. Therefore, their detection in wastewater can reflect current infections within the source population. To date, no viral study has been performed using the sewage of any large [...] Read more.

Sewage-associated viruses can cause several human and animal diseases, such as gastroenteritis, hepatitis, and respiratory infections. Therefore, their detection in wastewater can reflect current infections within the source population. To date, no viral study has been performed using the sewage of any large South American city. In this study, we used viral metagenomics to obtain a single sample snapshot of the RNA virosphere in the wastewater from Santiago de Chile, the seventh largest city in the Americas. Despite the overrepresentation of dsRNA viruses, our results show that Santiago’s sewage RNA virosphere was composed mostly of unknown sequences (88%), while known viral sequences were dominated by viruses that infect bacteria (60%), invertebrates (37%) and humans (2.4%). Interestingly, we discovered three novel genogroups within the Picobirnaviridae family that can fill major gaps in this taxa’s evolutionary history. We also demonstrated the dominance of emerging Rotavirus genotypes, such as G8 and G6, that have displaced other classical genotypes, which is consistent with recent clinical reports. This study supports the usefulness of sewage viral metagenomics for public health surveillance. Moreover, it demonstrates the need to monitor the viral component during the wastewater treatment and recycling process, where this virome can constitute a reservoir of human pathogens. Full article

(This article belongs to the Section Animal Viruses)

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Graphical abstract

3 pages, 140 KiB

Open AccessEditorial

Special Issue: “Plant Virus Pathogenesis and Disease Control”

by Bryce W. Falk and Shahideh Nouri

Viruses 2020, 12(9), 1049; https://doi.org/10.3390/v12091049 - 21 Sep 2020

Cited by 3 | Viewed by 4013

Abstract

Plant viruses are emerging and re-emerging to cause important diseases in many plants that humans grow for food and/or fiber, and sustainable, effective strategies for controlling many plant virus diseases remain unavailable [...] Full article

(This article belongs to the Special Issue Plant Virus Pathogenesis and Disease Control)

13 pages, 10351 KiB

Open AccessBrief Report

The Emergence of a vv + MDV Can Break through the Protections Provided by the Current Vaccines

by Meng-ya Shi, Min Li, Wei-wei Wang, Qiao-mu Deng, Qiu-hong Li, Yan-li Gao, Pei-kun Wang, Teng Huang and Ping Wei

Viruses 2020, 12(9), 1048; https://doi.org/10.3390/v12091048 - 20 Sep 2020

Cited by 20 | Viewed by 3711

Abstract

Marek’s disease (MD) is an infectious malignant T-cell lymphoma proliferative disease caused by Marek’s disease virus (MDV). In recent years, the emergence of very virulent (vv) and/or very virulent plus (vv +) strains of MDV in the field has been suggested as one [...] Read more.

Marek’s disease (MD) is an infectious malignant T-cell lymphoma proliferative disease caused by Marek’s disease virus (MDV). In recent years, the emergence of very virulent (vv) and/or very virulent plus (vv +) strains of MDV in the field has been suggested as one of the causes of vaccination failure. The pathogenicity of the MDV strain GX18NNM4, isolated from a clinical outbreak in a broiler breeder flock that was vaccinated with CVI988/Rispens, was investigated. In the vaccination-challenge test, GX18NNM4 was able to break through the protections provided by the vaccines CVI988 and 814. It also significantly reduced body weight gain and caused marked gross lesions and a large area of infiltration of neoplastic lymphocyte cells in the heart, liver, pancreas, etc. of the infected birds. In addition, the expressions of programmed death 1 (PD-1) and its ligand, programmed death ligand 1 (PD-L1), in the spleens and cecal tonsils (CTs) of the unvaccinated challenged birds were significantly increased compared to those in the vaccinated challenged birds, indicating that the PD-1/PD-L1 pathway is related to immune evasion mechanisms. The results showed that the GX18NNM4 strain could cause severe immunosuppression and significantly decrease the protections provided by the current commercial vaccines, thus showing GX18NNM4 to be a vv + MDV strain. Full article

(This article belongs to the Special Issue Animal Herpesviruses Pathogenesis and Immunity)

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15 pages, 897 KiB

Open AccessArticle

Renal Allograft Biopsies with Polyomavirus BK Nephropathy: Turin Transplant Center, 2015–19

by Elisa Zanotto, Anna Allesina, Antonella Barreca, Francesca Sidoti, Ester Gallo, Paolo Bottino, Marco Iannaccone, Gabriele Bianco, Luigi Biancone, Rossana Cavallo and Cristina Costa

Viruses 2020, 12(9), 1047; https://doi.org/10.3390/v12091047 - 20 Sep 2020

Cited by 6 | Viewed by 2997

Abstract

Background: In kidney transplant patients, polyomavirus-associated nephropathy (PVAN) represents a serious complication; the key factor for the development of PVAN is immunosuppression level and modulation of anti-rejection treatment represents the first line of intervention. Allograft biopsy and histology remain the criterion standard for [...] Read more.

Background: In kidney transplant patients, polyomavirus-associated nephropathy (PVAN) represents a serious complication; the key factor for the development of PVAN is immunosuppression level and modulation of anti-rejection treatment represents the first line of intervention. Allograft biopsy and histology remain the criterion standard for diagnosing PVAN. Methods: All consecutive renal biopsies with the diagnosis of PVAN carried out at the University Hospital City of Health and Science of Turin over a five-years period were studied. Renal allograft biopsy was performed due to renal function alterations associated to medium-high polyomavirus BK (BKV)-DNA levels on plasma specimen. Results: A total of 21 patients underwent a first biopsy to diagnose a possible BKV nephropathy, in 18, a second biopsy was made, in eight, a third biopsy, and finally, three underwent the fourth renal biopsy; following the results of each biopsies, immunosuppressant agents dosages were modified in order to reduce the effect of PVAN. Conclusions: In this study, the clinical and histological features of 21 kidney transplant recipients with BKV reactivation and development of PVAN are described. To date, the only treatment for PVAN consists in the reduction of immunosuppressive agents, constantly monitoring viral load. Full article

(This article belongs to the Special Issue BK Virus and Transplantation)

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19 pages, 2736 KiB

Open AccessArticle

PA from a Recent H9N2 (G1-Like) Avian Influenza A Virus (AIV) Strain Carrying Lysine 367 Confers Altered Replication Efficiency and Pathogenicity to Contemporaneous H5N1 in Mammalian Systems

by Ahmed Mostafa, Sara H. Mahmoud, Mahmoud Shehata, Christin Müller, Ahmed Kandeil, Rabeh El-Shesheny, Hanaa Z. Nooh, Ghazi Kayali, Mohamed A. Ali and Stephan Pleschka

Viruses 2020, 12(9), 1046; https://doi.org/10.3390/v12091046 - 20 Sep 2020

Cited by 14 | Viewed by 4292

Abstract

Egypt is a hotspot for H5- and H9-subtype avian influenza A virus (AIV) infections and co-infections in poultry by both subtypes have been frequently reported. However, natural genetic reassortment of these subtypes has not been reported yet. Here, we evaluated the genetic compatibility [...] Read more.

Egypt is a hotspot for H5- and H9-subtype avian influenza A virus (AIV) infections and co-infections in poultry by both subtypes have been frequently reported. However, natural genetic reassortment of these subtypes has not been reported yet. Here, we evaluated the genetic compatibility and replication efficiency of reassortants between recent isolates of an Egyptian H5N1 and a H9N2 AIV (H5N1_EGY and H9N2_EGY). All internal viral proteins-encoding segments of the contemporaneous G1-like H9N2_EGY, expressed individually and in combination in the genetic background of H5N1_EGY, were genetically compatible with the other H5N1_EGY segments. At 37 °C the replication efficiencies of H5N1_EGY reassortants expressing the H9N2_EGY polymerase subunits PB2 and PA (H5N1_PB2-H9N2EGY, H5N1_PA-H9N2EGY) were higher than the wild-type H5N1_EGY in Madin-Darby canine kidney (MDCK-II) cells. This could not be correlated to viral polymerase activity as this was found to be improved for H5N1_PB2-H9N2EGY, but reduced for H5N1_PA-H9N2EGY. At 33 °C and 39 °C, H5N1_PB2-H9N2EGY and H5N1_PA-H9N2EGY replicated to higher levels than the wild-type H5N1_EGY in human Calu-3 and A549 cell lines. Nevertheless, in BALB/c mice both reassortants caused reduced mortality compared to the wild-type H5N1_EGY. Genetic analysis of the polymerase-encoding segments revealed that the PA_H9N2EGY and PB2_H9N2EGY encode for a distinct uncharacterized mammalian-like variation (367K) and a well-known mammalian signature (591K), respectively. Introducing the single substitution 367K into the PA of H5N1_EGY enabled the mutant virus H5N1_PA-R367K to replicate more efficiently at 37 °C in primary human bronchial epithelial (NHBE) cells and also in A549 and Calu-3 cells at 33 °C and 39 °C. Furthermore, H5N1_PA-R367K caused higher mortality in BALB/c mice. These findings demonstrate that H5N1 (Clade 2.2.1.2) reassortants carrying internal proteins-encoding segments of G1-like H9N2 viruses can emerge and may gain improved replication fitness. Thereby such H5N1/H9N2 reassortants could augment the zoonotic potential of H5N1 viruses, especially by acquiring unique mammalian-like aa signatures. Full article

(This article belongs to the Special Issue Evolution and Pathogenesis of Avian and Animal Influenza Viruses)

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9 pages, 2016 KiB

Open AccessArticle

RNAemia Corresponds to Disease Severity and Antibody Response in Hospitalized COVID-19 Patients

by Kirsten Alexandra Eberhardt, Charlotte Meyer-Schwickerath, Eva Heger, Elena Knops, Clara Lehmann, Jan Rybniker, Philipp Schommers, Dennis A. Eichenauer, Florian Kurth, Michael Ramharter, Rolf Kaiser, Udo Holtick, Florian Klein, Norma Jung and Veronica Di Cristanziano

Viruses 2020, 12(9), 1045; https://doi.org/10.3390/v12091045 - 18 Sep 2020

Cited by 46 | Viewed by 4916

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represents a global health emergency. To improve the understanding of the systemic component of SARS-CoV-2, we investigated if viral load dynamics in plasma and respiratory samples are associated with antibody response and severity of coronavirus disease [...] Read more.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represents a global health emergency. To improve the understanding of the systemic component of SARS-CoV-2, we investigated if viral load dynamics in plasma and respiratory samples are associated with antibody response and severity of coronavirus disease 2019 (COVID-19). SARS-CoV-2 RNA was found in plasma samples from 14 (44%) out of 32 patients. RNAemia was detected in 5 out of 6 fatal cases. Peak IgG values were significantly lower in mild/moderate than in severe (0.6 (interquartile range, IQR, 0.4–3.2) vs. 11.8 (IQR, 9.9–13.0), adjusted p = 0.003) or critical cases (11.29 (IQR, 8.3–12.0), adjusted p = 0.042). IgG titers were significantly associated with virus Ct (Cycle threshold) value in plasma and respiratory specimens ((ß = 0.4, 95% CI (confidence interval, 0.2; 0.5), p < 0.001 and ß = 0.5, 95% CI (0.2; 0.6), p = 0.002). A classification as severe or a critical case was additionally inversely associated with Ct values in plasma in comparison to mild/moderate cases (ß = −3.3, 95% CI (−5.8; 0.8), p = 0.024 and ß = −4.4, 95% CI (−7.2; 1.6), p = 0.007, respectively). Based on the present data, our hypothesis is that the early stage of SARS-CoV-2 infection is characterized by a primary RNAemia, as a potential manifestation of a systemic infection. Additionally, the viral load in plasma seems to be associated with a worse disease outcome. Full article

(This article belongs to the Collection Coronaviruses)

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21 pages, 3726 KiB

Open AccessArticle

Generation of Combinatorial Lentiviral Vectors Expressing Multiple Anti-Hepatitis C Virus shRNAs and Their Validation on a Novel HCV Replicon Double Reporter Cell Line

by Hossein M. Elbadawy, Mohi I. Mohammed Abdul, Naif Aljuhani, Adriana Vitiello, Francesco Ciccarese, Mohamed A. Shaker, Heba M. Eltahir, Giorgio Palù, Veronica Di Antonio, Hanieh Ghassabian, Claudia Del Vecchio, Cristiano Salata, Elisa Franchin, Eleonora Ponterio, Saleh Bahashwan, Khaled Thabet, Mekky M. Abouzied, Ahmed M. Shehata, Cristina Parolin, Arianna Calistri and Gualtiero Alvisi Show full author list Hide full author list

Viruses 2020, 12(9), 1044; https://doi.org/10.3390/v12091044 - 18 Sep 2020

Cited by 5 | Viewed by 3962

Abstract

Despite the introduction of directly acting antivirals (DAAs), for the treatment of hepatitis C virus (HCV) infection, their cost, patient compliance, and viral resistance are still important issues to be considered. Here, we describe the generation of a novel JFH1-based HCV subgenomic replicon [...] Read more.

Despite the introduction of directly acting antivirals (DAAs), for the treatment of hepatitis C virus (HCV) infection, their cost, patient compliance, and viral resistance are still important issues to be considered. Here, we describe the generation of a novel JFH1-based HCV subgenomic replicon double reporter cell line suitable for testing different antiviral drugs and therapeutic interventions. This cells line allowed a rapid and accurate quantification of cell growth/viability and HCV RNA replication, thus discriminating specific from unspecific antiviral effects caused by DAAs or cytotoxic compounds, respectively. By correlating cell number and virus replication, we could confirm the inhibitory effect on the latter of cell over confluency and characterize an array of lentiviral vectors expressing single, double, or triple cassettes containing different combinations of short hairpin (sh)RNAs, targeting both highly conserved viral genome sequences and cellular factors crucial for HCV replication. While all vectors were effective in reducing HCV replication, the ones targeting viral sequences displayed a stronger antiviral effect, without significant cytopathic effects. Such combinatorial platforms as well as the developed double reporter cell line might find application both in setting-up anti-HCV gene therapy approaches and in studies aimed at further dissecting the viral biology/pathogenesis of infection. Full article

(This article belongs to the Special Issue RNA Interference (RNAi) for Antiviral Therapy)

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18 pages, 5160 KiB

Open AccessArticle

Merkel Cell Polyomavirus Large T Antigen Unique Domain Regulates Its Own Protein Stability and Cell Growth

by Nnenna Nwogu, Luz E. Ortiz and Hyun Jin Kwun

Viruses 2020, 12(9), 1043; https://doi.org/10.3390/v12091043 - 18 Sep 2020

Cited by 7 | Viewed by 4196

Abstract

Merkel cell polyomavirus (MCV) is the only known human oncogenic virus in the polyomaviridae family and the etiological agent of most Merkel cell carcinomas (MCC). MCC is an aggressive and highly metastatic skin cancer with a propensity for recurrence and poor prognosis. Large [...] Read more.

Merkel cell polyomavirus (MCV) is the only known human oncogenic virus in the polyomaviridae family and the etiological agent of most Merkel cell carcinomas (MCC). MCC is an aggressive and highly metastatic skin cancer with a propensity for recurrence and poor prognosis. Large tumor antigen (LT), is an essential oncoprotein for MCV transcription, viral replication, and cancer cell proliferation. MCV LT is a short-lived protein that encodes a unique domain: MCV LT unique regions (MURs). These domains consist of phosphorylation sites that interact with multiple E3 ligases, thus limiting LT expression and consequently, viral replication. In this study, we show that MURs are necessary for regulating LT stability via multiple E3 ligase interactions, resulting in cell growth arrest. While expression of wild-type MCV LT induced a decrease in cellular proliferation, deletion of the MUR domains resulted in increased LT stability and cell proliferation. Conversely, addition of MURs to SV40 LT propagated E3 ligase interactions, which in turn, reduced SV40 LT stability and decreased cell growth activity. Our results demonstrate that compared to other human polyomaviruses (HPyVs), MCV LT has evolved to acquire the MUR domains that are essential for MCV LT autoregulation, potentially leading to viral latency and MCC. Full article

(This article belongs to the Special Issue Polyomaviruses)

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14 pages, 3035 KiB

Open AccessArticle

Divergent Influenza-Like Viruses of Amphibians and Fish Support an Ancient Evolutionary Association

by Rhys Parry, Michelle Wille, Olivia M. H. Turnbull, Jemma L. Geoghegan and Edward C. Holmes

Viruses 2020, 12(9), 1042; https://doi.org/10.3390/v12091042 - 18 Sep 2020

Cited by 23 | Viewed by 8520

Abstract

Influenza viruses (family Orthomyxoviridae) infect a variety of vertebrates, including birds, humans, and other mammals. Recent metatranscriptomic studies have uncovered divergent influenza viruses in amphibians, fish and jawless vertebrates, suggesting that these viruses may be widely distributed. We sought to identify additional [...] Read more.

Influenza viruses (family Orthomyxoviridae) infect a variety of vertebrates, including birds, humans, and other mammals. Recent metatranscriptomic studies have uncovered divergent influenza viruses in amphibians, fish and jawless vertebrates, suggesting that these viruses may be widely distributed. We sought to identify additional vertebrate influenza-like viruses through the analysis of publicly available RNA sequencing data. Accordingly, by data mining, we identified the complete coding segments of five divergent vertebrate influenza-like viruses. Three fell as sister lineages to influenza B virus: salamander influenza-like virus in Mexican walking fish (Ambystoma mexicanum) and plateau tiger salamander (Ambystoma velasci), Siamese algae-eater influenza-like virus in Siamese algae-eater fish (Gyrinocheilus aymonieri) and chum salmon influenza-like virus in chum salmon (Oncorhynchus keta). Similarly, we identified two influenza-like viruses of amphibians that fell as sister lineages to influenza D virus: cane toad influenza-like virus and the ornate chorus frog influenza-like virus, in the cane toad (Rhinella marina) and ornate chorus frog (Microhyla fissipes), respectively. Despite their divergent phylogenetic positions, these viruses retained segment conservation and splicing consistent with transcriptional regulation in influenza B and influenza D viruses, and were detected in respiratory tissues. These data suggest that influenza viruses have been associated with vertebrates for their entire evolutionary history. Full article

(This article belongs to the Section Animal Viruses)

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24 pages, 3980 KiB

Open AccessArticle

Identification of Inhibitors of ZIKV Replication

by Desarey Morales Vasquez, Jun-Gyu Park, Ginés Ávila-Pérez, Aitor Nogales, Juan Carlos de la Torre, Fernando Almazan and Luis Martinez-Sobrido

Viruses 2020, 12(9), 1041; https://doi.org/10.3390/v12091041 - 18 Sep 2020

Cited by 16 | Viewed by 4222

Abstract

Zika virus (ZIKV) was identified in 1947 in the Zika forest of Uganda and it has emerged recently as a global health threat, with recurring outbreaks and its associations with congenital microcephaly through maternal fetal transmission and Guillain-Barré syndrome. Currently, there are no [...] Read more.

Zika virus (ZIKV) was identified in 1947 in the Zika forest of Uganda and it has emerged recently as a global health threat, with recurring outbreaks and its associations with congenital microcephaly through maternal fetal transmission and Guillain-Barré syndrome. Currently, there are no United States (US) Food and Drug Administration (FDA)-approved vaccines or antivirals to treat ZIKV infections, which underscores an urgent medical need for the development of disease intervention strategies to treat ZIKV infection and associated disease. Drug repurposing offers various advantages over developing an entirely new drug by significantly reducing the timeline and resources required to advance a candidate antiviral into the clinic. Screening the ReFRAME library, we identified ten compounds with antiviral activity against the prototypic mammarenavirus lymphocytic choriomeningitis virus (LCMV). Moreover, we showed the ability of these ten compounds to inhibit influenza A and B virus infections, supporting their broad-spectrum antiviral activity. In this study, we further evaluated the broad-spectrum antiviral activity of the ten identified compounds by testing their activity against ZIKV. Among the ten compounds, Azaribine (SI-MTT = 146.29), AVN-944 (SI-MTT = 278.16), and Brequinar (SI-MTT = 157.42) showed potent anti-ZIKV activity in post-treatment therapeutic conditions. We also observed potent anti-ZIKV activity for Mycophenolate mofetil (SI-MTT = 20.51), Mycophenolic acid (SI-MTT = 36.33), and AVN-944 (SI-MTT = 24.51) in pre-treatment prophylactic conditions and potent co-treatment inhibitory activity for Obatoclax (SI-MTT = 60.58), Azaribine (SI-MTT = 91.51), and Mycophenolate mofetil (SI-MTT = 73.26) in co-treatment conditions. Importantly, the inhibitory effect of these compounds was strain independent, as they similarly inhibited ZIKV strains from both African and Asian/American lineages. Our results support the broad-spectrum antiviral activity of these ten compounds and suggest their use for the development of antiviral treatment options of ZIKV infection. Full article

(This article belongs to the Section Animal Viruses)

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22 pages, 1773 KiB

Open AccessArticle

CBF-1 Promotes the Establishment and Maintenance of HIV Latency by Recruiting Polycomb Repressive Complexes, PRC1 and PRC2, at HIV LTR

by Adhikarimayum Lakhikumar Sharma, Joseph Hokello, Shilpa Sonti, Sonia Zicari, Lin Sun, Aseel Alqatawni, Michael Bukrinsky, Gary Simon, Ashok Chauhan, Rene Daniel and Mudit Tyagi

Viruses 2020, 12(9), 1040; https://doi.org/10.3390/v12091040 - 18 Sep 2020

Cited by 18 | Viewed by 3932

Abstract

The C-promoter binding factor-1 (CBF-1) is a potent and specific inhibitor of the human immunodeficiency virus (HIV)-1 LTR promoter. Here, we demonstrate that the knockdown of endogenous CBF-1 in latently infected primary CD4+ T cells, using specific small hairpin RNAs (shRNA), resulted in [...] Read more.

The C-promoter binding factor-1 (CBF-1) is a potent and specific inhibitor of the human immunodeficiency virus (HIV)-1 LTR promoter. Here, we demonstrate that the knockdown of endogenous CBF-1 in latently infected primary CD4+ T cells, using specific small hairpin RNAs (shRNA), resulted in the reactivation of latent HIV proviruses. Chromatin immunoprecipitation (ChIP) assays using latently infected primary T cells and Jurkat T-cell lines demonstrated that CBF-1 induces the establishment and maintenance of HIV latency by recruiting polycomb group (PcG/PRC) corepressor complexes or polycomb repressive complexes 1 and 2 (PRC1 and PRC2). Knockdown of CBF-1 resulted in the dissociation of PRCs corepressor complexes enhancing the recruitment of RNA polymerase II (RNAP II) at HIV LTR. Knockdown of certain components of PRC1 and PRC2 also led to the reactivation of latent proviruses. Similarly, the treatment of latently infected primary CD4+ T cells with the PRC2/EZH2 inhibitor, 3-deazaneplanocin A (DZNep), led to their reactivation. Full article

(This article belongs to the Special Issue HIV-1 Transcription Regulation)

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19 pages, 1184 KiB

Open AccessReview

Induction of the Antiviral Immune Response and Its Circumvention by Coronaviruses

by Ping Liu, Yan Hong, Bincai Yang, Prasha Shrestha, Nelam Sajjad and Ji-Long Chen

Viruses 2020, 12(9), 1039; https://doi.org/10.3390/v12091039 - 18 Sep 2020

Cited by 9 | Viewed by 5036

Abstract

Some coronaviruses are zoonotic viruses of human and veterinary medical importance. The novel coronavirus, severe acute respiratory symptoms coronavirus 2 (SARS-CoV-2), associated with the current global pandemic, is characterized by pneumonia, lymphopenia, and a cytokine storm in humans that has caused catastrophic impacts [...] Read more.

Some coronaviruses are zoonotic viruses of human and veterinary medical importance. The novel coronavirus, severe acute respiratory symptoms coronavirus 2 (SARS-CoV-2), associated with the current global pandemic, is characterized by pneumonia, lymphopenia, and a cytokine storm in humans that has caused catastrophic impacts on public health worldwide. Coronaviruses are known for their ability to evade innate immune surveillance exerted by the host during the early phase of infection. It is important to comprehensively investigate the interaction between highly pathogenic coronaviruses and their hosts. In this review, we summarize the existing knowledge about coronaviruses with a focus on antiviral immune responses in the respiratory and intestinal tracts to infection with severe coronaviruses that have caused epidemic diseases in humans and domestic animals. We emphasize, in particular, the strategies used by these coronaviruses to circumvent host immune surveillance, mainly including the hijack of antigen-presenting cells, shielding RNA intermediates in replication organelles, 2′-O-methylation modification for the evasion of RNA sensors, and blocking of interferon signaling cascades. We also provide information about the potential development of coronavirus vaccines and antiviral drugs. Full article

(This article belongs to the Special Issue Emerging Viruses 2020: Surveillance, Prevention, Evolution and Control)

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16 pages, 3618 KiB

Open AccessArticle

The Genetic Diversification of a Single Bluetongue Virus Strain Using an In Vitro Model of Alternating-Host Transmission

by Jennifer H. Kopanke, Justin S. Lee, Mark D. Stenglein and Christie E. Mayo

Viruses 2020, 12(9), 1038; https://doi.org/10.3390/v12091038 - 18 Sep 2020

Cited by 9 | Viewed by 3215

Abstract

Bluetongue virus (BTV) is an arbovirus that has been associated with dramatic epizootics in both wild and domestic ruminants in recent decades. As a segmented, double-stranded RNA virus, BTV can evolve via several mechanisms due to its genomic structure. However, the effect of [...] Read more.

Bluetongue virus (BTV) is an arbovirus that has been associated with dramatic epizootics in both wild and domestic ruminants in recent decades. As a segmented, double-stranded RNA virus, BTV can evolve via several mechanisms due to its genomic structure. However, the effect of BTV’s alternating-host transmission cycle on the virus’s genetic diversification remains poorly understood. Whole genome sequencing approaches offer a platform for investigating the effect of host-alternation across all ten segments of BTV’s genome. To understand the role of alternating hosts in BTV’s genetic diversification, a field isolate was passaged under three different conditions: (i) serial passages in Culicoides sonorensis cells, (ii) serial passages in bovine pulmonary artery endothelial cells, or (iii) alternating passages between insect and bovine cells. Aliquots of virus were sequenced, and single nucleotide variants were identified. Measures of viral population genetics were used to quantify the genetic diversification that occurred. Two consensus variants in segments 5 and 10 occurred in virus from all three conditions. While variants arose across all passages, measures of genetic diversity remained largely similar across cell culture conditions. Despite passage in a relaxed in vitro system, we found that this BTV isolate exhibited genetic stability across passages and conditions. Our findings underscore the valuable role that whole genome sequencing may play in improving understanding of viral evolution and highlight the genetic stability of BTV. Full article

(This article belongs to the Section Invertebrate Viruses)

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15 pages, 1266 KiB

Open AccessReview

Functional Characterization of Pepper Vein Banding Virus-Encoded Proteins and Their Interactions: Implications in Potyvirus Infection

by Pallavi Sabharwal and Handanahal S. Savithri

Viruses 2020, 12(9), 1037; https://doi.org/10.3390/v12091037 - 17 Sep 2020

Cited by 4 | Viewed by 3556

Abstract

Pepper vein banding virus (PVBV) is a distinct species in the Potyvirus genus which infects economically important plants in several parts of India. Like other potyviruses, PVBV encodes multifunctional proteins, with several interaction partners, having implications at different stages of the potyviral infection. [...] Read more.

Pepper vein banding virus (PVBV) is a distinct species in the Potyvirus genus which infects economically important plants in several parts of India. Like other potyviruses, PVBV encodes multifunctional proteins, with several interaction partners, having implications at different stages of the potyviral infection. In this review, we summarize the functional characterization of different PVBV-encoded proteins with an emphasis on their interaction partners governing the multifunctionality of potyviral proteins. Intrinsically disordered domains/regions of these proteins play an important role in their interactions with other proteins. Deciphering the function of PVBV-encoded proteins and their interactions with cognitive partners will help in understanding the putative mechanisms by which the potyviral proteins are regulated at different stages of the viral life-cycle. This review also discusses PVBV virus-like particles (VLPs) and their potential applications in nanotechnology. Further, virus-like nanoparticle-cell interactions and intracellular fate of PVBV VLPs are also discussed. Full article

(This article belongs to the Special Issue The Complexity of the Potyviral Interaction Network)

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15 pages, 1991 KiB

Open AccessArticle

Molecular Characterisation of a Novel and Highly Divergent Passerine Adenovirus 1

by Ajani Athukorala, Jade K. Forwood, David N. Phalen and Subir Sarker

Viruses 2020, 12(9), 1036; https://doi.org/10.3390/v12091036 - 17 Sep 2020

Cited by 14 | Viewed by 4328

Abstract

Wild birds harbour a large number of adenoviruses that remain uncharacterised with respect to their genomic organisation, diversity, and evolution within complex ecosystems. Here, we present the first complete genome sequence of an atadenovirus from a passerine bird that is tentatively named Passerine [...] Read more.

Wild birds harbour a large number of adenoviruses that remain uncharacterised with respect to their genomic organisation, diversity, and evolution within complex ecosystems. Here, we present the first complete genome sequence of an atadenovirus from a passerine bird that is tentatively named Passerine adenovirus 1 (PaAdV-1). The PaAdV-1 genome is 39,664 bp in length, which was the longest atadenovirus to be sequenced, to the best of our knowledge, and contained 42 putative genes. Its genome organisation was characteristic of the members of genus Atadenovirus; however, the novel PaAdV-1 genome was highly divergent and showed the highest sequence similarity with psittacine adenovirus-3 (55.58%). Importantly, PaAdV-1 complete genome was deemed to contain 17 predicted novel genes that were not present in any other adenoviruses sequenced to date, with several of these predicted novel genes encoding proteins that harbour transmembrane helices. Subsequent analysis of the novel PaAdV-1 genome positioned phylogenetically to a distinct sub-clade with all others sequenced atadenoviruses and did not show any obvious close evolutionary relationship. This study concluded that the PaAdV-1 complete genome described here is not closely related to any other adenovirus isolated from avian or other natural host species and that it should be considered a separate species. Full article

(This article belongs to the Special Issue Animal and Wildlife Viruses)

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13 pages, 1561 KiB

Open AccessArticle

Evolutionary Study of the Crassphage Virus at Gene Level

by Alessandro Rossi, Laura Treu, Stefano Toppo, Henrike Zschach, Stefano Campanaro and Bas E. Dutilh

Viruses 2020, 12(9), 1035; https://doi.org/10.3390/v12091035 - 17 Sep 2020

Cited by 9 | Viewed by 4326

Abstract

crAss-like viruses are a putative family of bacteriophages recently discovered. The eponym of the clade, crAssphage, is an enteric bacteriophage estimated to be present in at least half of the human population and it constitutes up to 90% of the sequences in some [...] Read more.

crAss-like viruses are a putative family of bacteriophages recently discovered. The eponym of the clade, crAssphage, is an enteric bacteriophage estimated to be present in at least half of the human population and it constitutes up to 90% of the sequences in some human fecal viral metagenomic datasets. We focused on the evolutionary dynamics of the genes encoded on the crAssphage genome. By investigating the conservation of the genes, a consistent variation in the evolutionary rates across the different functional groups was found. Gene duplications in crAss-like genomes were detected. By exploring the differences among the functional categories of the genes, we confirmed that the genes encoding capsid proteins were the most ubiquitous, despite their overall low sequence conservation. It was possible to identify a core of proteins whose evolutionary trees strongly correlate with each other, suggesting their genetic interaction. This group includes the capsid proteins, which are thus established as extremely suitable for rebuilding the phylogenetic tree of this viral clade. A negative correlation between the ubiquity and the conservation of viral protein sequences was shown. Together, this study provides an in-depth picture of the evolution of different genes in crAss-like viruses. Full article

(This article belongs to the Special Issue Bioinformatics and Computational Approaches in Viral Genomics and Evolution)

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20 pages, 3415 KiB

Open AccessReview

Regulation of KSHV Latency and Lytic Reactivation

by Grant Broussard and Blossom Damania

Viruses 2020, 12(9), 1034; https://doi.org/10.3390/v12091034 - 17 Sep 2020

Cited by 70 | Viewed by 7977

Abstract

Kaposi’s sarcoma-associated herpesvirus (KSHV) is associated with three malignancies— Kaposi’s sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman’s disease (MCD). Central to the pathogenesis of these diseases is the KSHV viral life cycle, which is composed of a quiescent latent phase and [...] Read more.

Kaposi’s sarcoma-associated herpesvirus (KSHV) is associated with three malignancies— Kaposi’s sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman’s disease (MCD). Central to the pathogenesis of these diseases is the KSHV viral life cycle, which is composed of a quiescent latent phase and a replicative lytic phase. While the establishment of latency enables persistent KSHV infection and evasion of the host immune system, lytic replication is essential for the dissemination of the virus between hosts and within the host itself. The transition between these phases, known as lytic reactivation, is controlled by a complex set of environmental, host, and viral factors. The effects of these various factors converge on the regulation of two KSHV proteins whose functions facilitate each phase of the viral life cycle—latency-associated nuclear antigen (LANA) and the master switch of KSHV reactivation, replication and transcription activator (RTA). This review presents the current understanding of how the transition between the phases of the KSHV life cycle is regulated, how the various phases contribute to KSHV pathogenesis, and how the viral life cycle can be exploited as a therapeutic target. Full article

(This article belongs to the Special Issue New Advances in Kaposi's Sarcoma-Associated Herpesvirus Research)

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19 pages, 5398 KiB

Open AccessReview

Progress in the Development of Universal Influenza Vaccines

by Wenqiang Sun, Tingrong Luo, Wenjun Liu and Jing Li

Viruses 2020, 12(9), 1033; https://doi.org/10.3390/v12091033 - 17 Sep 2020

Cited by 32 | Viewed by 5505

Abstract

Influenza viruses pose a significant threat to human health. They are responsible for a large number of deaths annually and have a serious impact on the global economy. There are numerous influenza virus subtypes, antigenic variations occur continuously, and epidemic trends are difficult [...] Read more.

Influenza viruses pose a significant threat to human health. They are responsible for a large number of deaths annually and have a serious impact on the global economy. There are numerous influenza virus subtypes, antigenic variations occur continuously, and epidemic trends are difficult to predict—all of which lead to poor outcomes of routine vaccination against targeted strain subtypes. Therefore, the development of universal influenza vaccines still constitutes the ideal strategy for controlling influenza. This article reviews the progress in development of universal vaccines directed against the conserved regions of hemagglutinin (HA), neuraminidase (NA), and other structural proteins of influenza viruses using new technologies and strategies with the goals of enhancing our understanding of universal influenza vaccines and providing a reference for research into the exploitation of natural immunity against influenza viruses. Full article

(This article belongs to the Special Issue Influenza Virus Vaccines)

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16 pages, 5904 KiB

Open AccessArticle

Abrogating ALIX Interactions Results in Stuttering of the ESCRT Machinery

by Shilpa Gupta, Mourad Bendjennat and Saveez Saffarian

Viruses 2020, 12(9), 1032; https://doi.org/10.3390/v12091032 - 16 Sep 2020

Cited by 9 | Viewed by 3522

Abstract

Endosomal sorting complexes required for transport (ESCRT) proteins assemble on budding cellular membranes and catalyze their fission. Using live imaging of HIV virions budding from cells, we followed recruitment of ESCRT proteins ALIX, CHMP4B and VPS4. We report that the ESCRT proteins transiently [...] Read more.

Endosomal sorting complexes required for transport (ESCRT) proteins assemble on budding cellular membranes and catalyze their fission. Using live imaging of HIV virions budding from cells, we followed recruitment of ESCRT proteins ALIX, CHMP4B and VPS4. We report that the ESCRT proteins transiently co-localize with virions after completion of virion assembly for durations of 45 ± 30 s. We show that mutagenizing the YP domain of Gag which is the primary ALIX binding site or depleting ALIX from cells results in multiple recruitments of the full ESCRT machinery on the same virion (referred to as stuttering where the number of recruitments to the same virion >3). The stuttering recruitments are approximately 4 ± 3 min apart and have the same stoichiometry of ESCRTs and same residence time (45 ± 30 s) as the single recruitments in wild type interactions. Our observations suggest a role for ALIX during fission and question the linear model of ESCRT recruitment, suggesting instead a more complex co-assembly model. Full article

(This article belongs to the Special Issue The 11th International Retroviral Nucleocapsid and Assembly Symposium)

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13 pages, 1874 KiB

Open AccessCommunication

Avian Influenza Virus Prevalence and Subtype Diversity in Wild Birds in Shanghai, China, 2016–2018

by Ling Tang, Wangjun Tang, Xiaofang Li, Chuanxia Hu, Di Wu, Tianhou Wang and Guimei He

Viruses 2020, 12(9), 1031; https://doi.org/10.3390/v12091031 - 16 Sep 2020

Cited by 11 | Viewed by 3783

Abstract

From 2016 to 2018, surveillance of influenza A viruses in wild birds was conducted in Shanghai, located at the East Asian–Australian flyway, China. A total of 5112 samples from 51 species of wild birds were collected from three different wetlands. The total three-year [...] Read more.

From 2016 to 2018, surveillance of influenza A viruses in wild birds was conducted in Shanghai, located at the East Asian–Australian flyway, China. A total of 5112 samples from 51 species of wild birds were collected from three different wetlands. The total three-year prevalence of influenza A viruses among them was 8.8%, as assessed using real-time polymerase chain reaction (PCR) methods, and the total prevalence was higher in Anseriformes (26.3%) than in the Charadriiformes (2.3%) and the other orders (2.4%) in the Chongmin wetlands. Anseriformes should be the key monitoring group in future surveillance efforts. The peak prevalence of influenza A viruses in Charadriiformes were in April and September, and in other bird orders, the peaks were in November and December. Twelve subtypes of haemagglutinin (HA; H1–H12) and eight subtypes of neuraminidase (NA; N1, N2, N4–N9) were identified in 21 different combinations. The greatest subtype diversity could be found in common teal, suggesting that this species of the bird might play an important role in the ecology and epidemiology of influenza A viruses in Shanghai. These results will increase our understanding of the ecology and epidemiology of influenza A viruses in wild bird hosts in eastern China, and provide references for subsequent surveillance of influenza A virus in wild birds in this area. Full article

(This article belongs to the Section Animal Viruses)

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16 pages, 3573 KiB

Open AccessArticle

Detection and Phylogenetic Analyses of Taura Syndrome Virus from Archived Davidson’s-Fixed Paraffin-Embedded Shrimp Tissue

by Lauren Marie Ochoa, Roberto Cruz-Flores and Arun K. Dhar

Viruses 2020, 12(9), 1030; https://doi.org/10.3390/v12091030 - 16 Sep 2020

Cited by 10 | Viewed by 3710

Abstract

Taura syndrome is a World Organization for Animal Health (OIE)-listed disease of marine shrimp that is caused by Taura syndrome virus (TSV), a single-stranded RNA virus. Here we demonstrate the utility of using 15-year-old archived Davidson’s-fixed paraffin-embedded (DFPE) shrimp tissues for TSV detection [...] Read more.

Taura syndrome is a World Organization for Animal Health (OIE)-listed disease of marine shrimp that is caused by Taura syndrome virus (TSV), a single-stranded RNA virus. Here we demonstrate the utility of using 15-year-old archived Davidson’s-fixed paraffin-embedded (DFPE) shrimp tissues for TSV detection and phylogenetic analyses. Total RNA was isolated from known TSV-infected DFPE tissues using three commercially available kits and the purity and ability to detect TSV in the isolated RNA were compared. TSV was successfully detected through RT-qPCR in all the tested samples. Among the TSV-specific primers screened through RT-PCR, primer pair TSV-20 for the RNA-dependent RNA polymerase (RdRp), primers TSV-15 and TSV-16 for the capsid protein gene VP2 and primers TSV-5 for the capsid protein gene VP1 amplified the highest number of samples. To assess the phylogenetic relation among different TSV isolates, the VP1 gene was amplified and sequenced in overlapping segments. Concatenated sequences from smaller fragments were taken for phylogenetic analyses. The results showed that the TSV isolates from this study generally clustered with homologous isolates from the corresponding geographical regions indicating RNA derived from DFPE tissues can be used for pathogen detection and retrospective analyses. The ability to perform genomic characterization from archived tissue will expedite pathogen discovery, development of diagnostic tools and prevent disease spread in shrimp and potentially other aquaculture species worldwide. Full article

(This article belongs to the Section Animal Viruses)

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21 pages, 2563 KiB

Open AccessArticle

Identification and Distribution of Novel Cressdnaviruses and Circular Molecules in Four Penguin Species in South Georgia and the Antarctic Peninsula

by Hila Levy, Rafaela S. Fontenele, Ciara Harding, Crystal Suazo, Simona Kraberger, Kara Schmidlin, Anni Djurhuus, Caitlin E. Black, Tom Hart, Adrian L. Smith and Arvind Varsani

Viruses 2020, 12(9), 1029; https://doi.org/10.3390/v12091029 - 16 Sep 2020

Cited by 11 | Viewed by 4376

Abstract

There is growing interest in uncovering the viral diversity present in wild animal species. The remote Antarctic region is home to a wealth of uncovered microbial diversity, some of which is associated with its megafauna, including penguin species, the dominant avian biota. Penguins [...] Read more.

There is growing interest in uncovering the viral diversity present in wild animal species. The remote Antarctic region is home to a wealth of uncovered microbial diversity, some of which is associated with its megafauna, including penguin species, the dominant avian biota. Penguins interface with a number of other biota in their roles as marine mesopredators and several species overlap in their ranges and habitats. To characterize the circular single-stranded viruses related to those in the phylum Cressdnaviricota from these environmental sentinel species, cloacal swabs (n = 95) were obtained from King Penguins in South Georgia, and congeneric Adélie Penguins, Chinstrap Penguins, and Gentoo Penguins across the South Shetland Islands and Antarctic Peninsula. Using a combination of high-throughput sequencing, abutting primers-based PCR recovery of circular genomic elements, cloning, and Sanger sequencing, we detected 97 novel sequences comprising 40 ssDNA viral genomes and 57 viral-like circular molecules from 45 individual penguins. We present their detection patterns, with Chinstrap Penguins harboring the highest number of new sequences. The novel Antarctic viruses identified appear to be host-specific, while one circular molecule was shared between sympatric Chinstrap and Gentoo Penguins. We also report viral genotype sharing between three adult-chick pairs, one in each Pygoscelid species. Sequence similarity network approaches coupled with Maximum likelihood phylogenies of the clusters indicate the 40 novel viral genomes do not fall within any known viral families and likely fall within the recently established phylum Cressdnaviricota based on their replication-associated protein sequences. Similarly, 83 capsid protein sequences encoded by the viruses or viral-like circular molecules identified in this study do not cluster with any of those encoded by classified viral groups. Further research is warranted to expand knowledge of the Antarctic virome and would help elucidate the importance of viral-like molecules in vertebrate host evolution. Full article

(This article belongs to the Special Issue Viromics)

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