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Viruses
Volume 10
Issue 5
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Viruses, Volume 10, Issue 5 (May 2018) – 62 articles

Cover Story (view full-size image): Plant virus-based vectors are valuable tools for recombinant gene expression and functional genomics for both fundamental research and translational application. Criniviruses, members of the family Closteroviridae, cause phloem-limited infections in several important crops worldwide, but none have been developed for use as vectors. Here, lettuce infectious yellows virus (LIYV) was engineered into a vector that is applicable for efficient protein expression and gene silencing to retain whitefly vector transmissibility, allowing it to be used in various plant species. View the paper here.
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20 pages, 308 KiB  
Review
Lessons Learned in Developing a Commercial FIV Vaccine: The Immunity Required for an Effective HIV-1 Vaccine
by Bikash Sahay and Janet K. Yamamoto
Viruses 2018, 10(5), 277; https://doi.org/10.3390/v10050277 - 22 May 2018
Cited by 11 | Viewed by 5111
Abstract
The feline immunodeficiency virus (FIV) vaccine called Fel-O-Vax® FIV is the first commercial FIV vaccine released worldwide for the use in domestic cats against global FIV subtypes (A–E). This vaccine consists of inactivated dual-subtype (A plus D) FIV-infected cells, whereas its prototype [...] Read more.
The feline immunodeficiency virus (FIV) vaccine called Fel-O-Vax® FIV is the first commercial FIV vaccine released worldwide for the use in domestic cats against global FIV subtypes (A–E). This vaccine consists of inactivated dual-subtype (A plus D) FIV-infected cells, whereas its prototype vaccine consists of inactivated dual-subtype whole viruses. Both vaccines in experimental trials conferred moderate-to-substantial protection against heterologous strains from homologous and heterologous subtypes. Importantly, a recent case-control field study of Fel-O-Vax-vaccinated cats with outdoor access and ≥3 years of annual vaccine boost, resulted in a vaccine efficacy of 56% in Australia where subtype-A viruses prevail. Remarkably, this protection rate is far better than the protection rate of 31.2% observed in the best HIV-1 vaccine (RV144) trial. Current review describes the findings from the commercial and prototype vaccine trials and compares their immune correlates of protection. The studies described in this review demonstrate the overarching importance of ant-FIV T-cell immunity more than anti-FIV antibody immunity in affording protection. Thus, future efforts in developing the next generation FIV vaccine and the first effective HIV-1 vaccine should consider incorporating highly conserved protective T-cell epitopes together with the conserved protective B-cell epitopes, but without inducing adverse factors that eliminate efficacy. Full article
(This article belongs to the Special Issue Nonprimate Lentivirus)
19 pages, 2836 KiB  
Article
Discovery and Biochemical Characterization of PlyP56, PlyN74, and PlyTB40—Bacillus Specific Endolysins
by Irina Etobayeva, Sara B. Linden, Farhang Alem, Laith Harb, Lucas Rizkalla, Philip D. Mosier, Allison A. Johnson, Louise Temple, Ramin M. Hakami and Daniel C. Nelson
Viruses 2018, 10(5), 276; https://doi.org/10.3390/v10050276 - 21 May 2018
Cited by 25 | Viewed by 5585
Abstract
Three Bacillus bacteriophage-derived endolysins, designated PlyP56, PlyN74, and PlyTB40, were identified, cloned, purified, and characterized for their antimicrobial properties. Sequence alignment reveals these endolysins have an N-terminal enzymatically active domain (EAD) linked to a C-terminal cell wall binding domain (CBD). PlyP56 has a [...] Read more.
Three Bacillus bacteriophage-derived endolysins, designated PlyP56, PlyN74, and PlyTB40, were identified, cloned, purified, and characterized for their antimicrobial properties. Sequence alignment reveals these endolysins have an N-terminal enzymatically active domain (EAD) linked to a C-terminal cell wall binding domain (CBD). PlyP56 has a Peptidase_M15_4/VanY superfamily EAD with a conserved metal binding motif and displays biological dependence on divalent ions for activity. In contrast, PlyN74 and PlyTB40 have T7 lysozyme-type Amidase_2 and carboxypeptidase T-type Amidase_3 EADs, respectively, which are members of the MurNAc-LAA superfamily, but are not homologs and thus do not have a shared protein fold. All three endolysins contain similar SH3-family CBDs. Although minor host range differences were noted, all three endolysins show relatively broad antimicrobial activity against members of the Bacillus cereus sensu lato group with the highest lytic activity against B. cereus ATCC 4342. Characterization studies determined the optimal lytic activity for these enzymes was at physiological pH (pH 7.0–8.0), over a broad temperature range (4–55 °C), and at low concentrations of NaCl (<50 mM). Direct comparison of lytic activity shows the PlyP56 enzyme to be twice as effective at lysing the cell wall peptidoglycan as PlyN74 or PlyTB40, suggesting PlyP56 is a good candidate for further antimicrobial development as well as bioengineering studies. Full article
(This article belongs to the Special Issue Phage Lytic Enzymes and Their Applications)
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15 pages, 1720 KiB  
Review
Live-Cell Imaging of Early Steps of Single HIV-1 Infection
by Ashwanth C. Francis and Gregory B. Melikyan
Viruses 2018, 10(5), 275; https://doi.org/10.3390/v10050275 - 19 May 2018
Cited by 29 | Viewed by 7157
Abstract
Live-cell imaging of single HIV-1 entry offers a unique opportunity to delineate the spatio-temporal regulation of infection. Novel virus labeling and imaging approaches enable the visualization of key steps of HIV-1 entry leading to nuclear import, integration into the host genome, and viral [...] Read more.
Live-cell imaging of single HIV-1 entry offers a unique opportunity to delineate the spatio-temporal regulation of infection. Novel virus labeling and imaging approaches enable the visualization of key steps of HIV-1 entry leading to nuclear import, integration into the host genome, and viral protein expression. Here, we discuss single virus imaging strategies, focusing on live-cell imaging of single virus fusion and productive uncoating that culminates in HIV-1 infection. Full article
(This article belongs to the Special Issue Application of Advanced Imaging to the Study of Virus Replication)
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8 pages, 679 KiB  
Article
The Occurrence of a Commercial Npro and Erns Double Mutant BVDV-1 Live-Vaccine Strain in Newborn Calves
by Kerstin Wernike, Anna Michelitsch, Andrea Aebischer, Uwe Schaarschmidt, Andrea Konrath, Hermann Nieper, Julia Sehl, Jens P. Teifke and Martin Beer
Viruses 2018, 10(5), 274; https://doi.org/10.3390/v10050274 - 19 May 2018
Cited by 12 | Viewed by 5235
Abstract
The major source for the spread of bovine viral diarrhea virus (BVDV) are in-utero infected, immunotolerant, persistently infected (PI) animals since they shed enormous amounts of viruses throughout their lives. During the sequence-based virus typing of diagnostic ear notch samples performed in the [...] Read more.
The major source for the spread of bovine viral diarrhea virus (BVDV) are in-utero infected, immunotolerant, persistently infected (PI) animals since they shed enormous amounts of viruses throughout their lives. During the sequence-based virus typing of diagnostic ear notch samples performed in the context of the obligatory German BVDV eradication program, the commercial Npro and Erns double mutant BVDV-1 live-vaccine strain KE-9 was detected in seven newborn calves; their mothers were immunized in the first trimester of gestation. Six calves either succumbed or were culled immediately, but the one remaining animal was closely monitored for six months. The viral RNA was detected in the skin sample taken in its first and fifth week of life, but the virus could not be isolated. Further skin biopsies that were taken at monthly intervals as well as every serum and urine sample, nasal, oral, and rectal swabs taken weekly tested BVDV negative. However, neutralizing titers against BVDV-1 remained at a consistently high level. To further control for virus shedding, a BVDV antibody and antigen negative calf was co-housed which remained negative throughout the study. The missing viremia, a lack of excretion of infectious virus and negative follow-up skin samples combined with consistently high antibody titers speak against the induction of the classical persistent infection by vaccination with recombinant KE-9 during gestation. We, therefore, suggest that the epidemiological impact of the RNA/antigen positivity for an extended period in the skin is very low. The detection of live-vaccine viruses in skin biopsies mainly represents a diagnostic issue in countries that implemented ear notch-based control programs; and KE9-specific RT-PCRs or sequence analysis can be used to identify these animals and avoid culling measures. Full article
(This article belongs to the Section Animal Viruses)
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13 pages, 1242 KiB  
Article
Following Acute Encephalitis, Semliki Forest Virus is Undetectable in the Brain by Infectivity Assays but Functional Virus RNA Capable of Generating Infectious Virus Persists for Life
by Rennos Fragkoudis, Catherine M. Dixon-Ballany, Adrian K. Zagrajek, Lukasz Kedzierski and John K. Fazakerley
Viruses 2018, 10(5), 273; https://doi.org/10.3390/v10050273 - 18 May 2018
Cited by 11 | Viewed by 5355
Abstract
Alphaviruses are mosquito-transmitted RNA viruses which generally cause acute disease including mild febrile illness, rash, arthralgia, myalgia and more severely, encephalitis. In the mouse, peripheral infection with Semliki Forest virus (SFV) results in encephalitis. With non-virulent strains, infectious virus is detectable in the [...] Read more.
Alphaviruses are mosquito-transmitted RNA viruses which generally cause acute disease including mild febrile illness, rash, arthralgia, myalgia and more severely, encephalitis. In the mouse, peripheral infection with Semliki Forest virus (SFV) results in encephalitis. With non-virulent strains, infectious virus is detectable in the brain, by standard infectivity assays, for around ten days. As we have shown previously, in severe combined immunodeficient (SCID) mice, infectious virus is detectable for months in the brain. Here we show that in MHC-II-/- mice, with no functional CD4 T-cells, infectious virus is also detectable in the brain for long periods. In contrast, in the brains of CD8-/- mice, virus RNA persists but infectious virus is not detectable. In SCID mice infected with SFV, repeated intraperitoneal administration of anti-SFV immune serum rapidly reduced the titer of infectious virus in the brain to undetectable, however virus RNA persisted. Repeated intraperitoneal passive transfer of immune serum resulted in maintenance of brain virus RNA, with no detectable infectious virus, for several weeks. When passive antibody transfer was stopped, antibody levels declined and infectious virus was again detectable in the brain. In aged immunocompetent mice, previously infected with SFV, immunosuppression of antibody responses many months after initial infection also resulted in renewed ability to detect infectious virus in the brain. In summary, antiviral antibodies control and determine whether infectious virus is detectable in the brain but immune responses cannot clear this infection from the brain. Functional virus RNA capable of generating infectious virus persists and if antibody levels decline, infectious virus is again detectable. Full article
(This article belongs to the Special Issue Advances in Alphavirus Research)
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17 pages, 2033 KiB  
Article
Adaptive Mutations in Influenza A/California/07/2009 Enhance Polymerase Activity and Infectious Virion Production
by Patrick D. Slaine, Cara MacRae, Mariel Kleer, Emily Lamoureux, Sarah McAlpine, Michelle Warhuus, André M. Comeau, Craig McCormick, Todd Hatchette and Denys A. Khaperskyy
Viruses 2018, 10(5), 272; https://doi.org/10.3390/v10050272 - 18 May 2018
Cited by 13 | Viewed by 6045
Abstract
Mice are not natural hosts for influenza A viruses (IAVs), but they are useful models for studying antiviral immune responses and pathogenesis. Serial passage of IAV in mice invariably causes the emergence of adaptive mutations and increased virulence. Here, we report the adaptation [...] Read more.
Mice are not natural hosts for influenza A viruses (IAVs), but they are useful models for studying antiviral immune responses and pathogenesis. Serial passage of IAV in mice invariably causes the emergence of adaptive mutations and increased virulence. Here, we report the adaptation of IAV reference strain A/California/07/2009(H1N1) (also known as CA/07) in outbred Swiss Webster mice. Serial passage led to increased virulence and lung titers, and dissemination of the virus to brains. We adapted a deep-sequencing protocol to identify and enumerate adaptive mutations across all genome segments. Among mutations that emerged during mouse-adaptation, we focused on amino acid substitutions in polymerase subunits: polymerase basic-1 (PB1) T156A and F740L and polymerase acidic (PA) E349G. These mutations were evaluated singly and in combination in minigenome replicon assays, which revealed that PA E349G increased polymerase activity. By selectively engineering three PB1 and PA mutations into the parental CA/07 strain, we demonstrated that these mutations in polymerase subunits decreased the production of defective viral genome segments with internal deletions and dramatically increased the release of infectious virions from mouse cells. Together, these findings increase our understanding of the contribution of polymerase subunits to successful host adaptation. Full article
(This article belongs to the Special Issue What’s New with Flu?)
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11 pages, 5402 KiB  
Article
Synergistic Viral Replication of Marek’s Disease Virus and Avian Leukosis Virus Subgroup J is Responsible for the Enhanced Pathogenicity in the Superinfection of Chickens
by Jing Zhou, Guo-Liang Zhao, Xiao-Man Wang, Xu-Sheng Du, Shuai Su, Chen-Gui Li, Venugopal Nair, Yong-Xiu Yao and Zi-Qiang Cheng
Viruses 2018, 10(5), 271; https://doi.org/10.3390/v10050271 - 18 May 2018
Cited by 20 | Viewed by 6532
Abstract
Superinfection of Marek’s disease virus (MDV) and avian leukosis virus subgroup J (ALV-J) causes lethal neoplasia and death in chickens. However, whether there is synergism between the two viruses in viral replication and pathogenicity has remained elusive. In this study, we found that [...] Read more.
Superinfection of Marek’s disease virus (MDV) and avian leukosis virus subgroup J (ALV-J) causes lethal neoplasia and death in chickens. However, whether there is synergism between the two viruses in viral replication and pathogenicity has remained elusive. In this study, we found that the superinfection of MDV and ALV-J increased the viral replication of the two viruses in RNA and protein level, and synergistically promoted the expression of IL-10, IL-6, and TGF-β in chicken embryo fibroblasts (CEF). Moreover, MDV and ALV-J protein expression in dual-infected cells detected by confocal laser scanning microscope appeared earlier in the cytoplasm and the nucleus, and caused more severe cytopathy than single infection, suggesting that synergistically increased MDV and ALV-J viral-protein biosynthesis is responsible for the severe cytopathy. In vivo, compared to the single virus infected chickens, the mortality and tumor formation rates increased significantly in MDV and ALV-J dual-infected chickens. Viral loads of MDV and ALV-J in tissues of dual-infected chickens were significantly higher than those of single-infected chickens. Histopathology observation showed that more severe inflammation and tumor cells metastases were present in dual-infected chickens. In the present study, we concluded that synergistic viral replication of MDV and ALV-J is responsible for the enhanced pathogenicity in superinfection of chickens. Full article
(This article belongs to the Special Issue Animal Models for Viral Diseases)
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14 pages, 2504 KiB  
Article
Avian Influenza Virus Subtype H9N2 Affects Intestinal Microbiota, Barrier Structure Injury, and Inflammatory Intestinal Disease in the Chicken Ileum
by Hongxin Li, Xiaolin Liu, Feiyang Chen, Kejing Zuo, Che Wu, Yiming Yan, Weiguo Chen, Wencheng Lin and Qingmei Xie
Viruses 2018, 10(5), 270; https://doi.org/10.3390/v10050270 - 18 May 2018
Cited by 63 | Viewed by 7930
Abstract
Avian influenza virus subtype H9N2 (H9N2 AIV) has caused significant losses to the poultry industry due to the high mortality associated with secondary infections attributable to E. coli. This study tries to address the underlying secondary mechanisms after H9N2 AIV infection. Initially, [...] Read more.
Avian influenza virus subtype H9N2 (H9N2 AIV) has caused significant losses to the poultry industry due to the high mortality associated with secondary infections attributable to E. coli. This study tries to address the underlying secondary mechanisms after H9N2 AIV infection. Initially, nine day-old specific pathogen-free chickens were assigned to control (uninfected) and H9N2-infected groups, respectively. Using Illumina sequencing, histological examination, and quantitative real-time PCR, it was found that H9N2 AIV caused intestinal microbiota disorder, injury, and inflammatory damage to the intestinal mucosa. Notably, the genera Escherichia, especially E. coli, significantly increased (p < 0.01) at five days post-infection (dpi), while Lactobacillus, Enterococcus, and other probiotic organisms were significantly reduced (p < 0.01). Simultaneously, the mRNA expression of tight junction proteins (ZO-1, claudin 3, and occludin), TFF2, and Muc2 were significantly reduced (p < 0.01), indicating the destruction of the intestinal epithelial cell tight junctions and the damage of mucin layer construction. Moreover, the mRNA expression of proinflammatory cytokines IFN-γ, IL-22, IFN-α, and IL-17A in intestinal epithelial cells were significantly upregulated, resulting in the inflammatory response and intestinal injury. Our findings may provide a theoretical basis for observed gastroenteritis-like symptoms such as diarrhea and secondary E. coli infection following H9N2 AIV infection. Full article
(This article belongs to the Special Issue Animal Models for Viral Diseases)
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6 pages, 1371 KiB  
Communication
A Novel Hepadnavirus Identified in an Immunocompromised Domestic Cat in Australia
by Mahdis Aghazadeh, Mang Shi, Vanessa R. Barrs, Alicia J. McLuckie, Scott A. Lindsay, Barbara Jameson, Bronte Hampson, Edward C. Holmes and Julia A. Beatty
Viruses 2018, 10(5), 269; https://doi.org/10.3390/v10050269 - 17 May 2018
Cited by 48 | Viewed by 17971
Abstract
High-throughput transcriptome sequencing allows for the unbiased detection of viruses in host tissues. The application of this technique to immunosuppressed animals facilitates the detection of viruses that might otherwise be excluded or contained in immunocompetent individuals. To identify potential viral pathogens infecting domestic [...] Read more.
High-throughput transcriptome sequencing allows for the unbiased detection of viruses in host tissues. The application of this technique to immunosuppressed animals facilitates the detection of viruses that might otherwise be excluded or contained in immunocompetent individuals. To identify potential viral pathogens infecting domestic cats we performed high-throughput transcriptome sequencing of tissues from cats infected with feline immunodeficiency virus (FIV). A novel member of the Hepadnaviridae, tentatively named domestic cat hepadnavirus, was discovered in a lymphoma sample and its complete 3187 bp genome characterized. Phylogenetic analysis placed the domestic cat hepadnavirus as a divergent member of mammalian orthohepadnaviruses that exhibits no close relationship to any other virus. DNA extracted from whole blood from pet cats was positive for the novel hepadnavirus by PCR in 6 of 60 (10%) FIV-infected cats and 2 of 63 (3.2%) FIV-uninfected cats. The higher prevalence of hepadnavirus viraemia detected in FIV-infected cats mirrors that seen in human immunodeficiency virus-infected humans coinfected with hepatitis B virus. In summary, we report the first hepadnavirus infection in a carnivore and the first in a companion animal. The natural history, epidemiology and pathogenic potential of domestic cat hepadnavirus merits additional investigation. Full article
(This article belongs to the Special Issue Emerging Viruses)
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18 pages, 2525 KiB  
Article
Paradoxical Effect of Chloroquine Treatment in Enhancing Chikungunya Virus Infection
by Pierre Roques, Simon-Djamel Thiberville, Laurence Dupuis-Maguiraga, Fok-Moon Lum, Karine Labadie, Frédéric Martinon, Gabriel Gras, Pierre Lebon, Lisa F. P. Ng, Xavier De Lamballerie and Roger Le Grand
Viruses 2018, 10(5), 268; https://doi.org/10.3390/v10050268 - 17 May 2018
Cited by 126 | Viewed by 18700
Abstract
Since 2005, Chikungunya virus (CHIKV) re-emerged and caused numerous outbreaks in the world, and finally, was introduced into the Americas in 2013. The lack of CHIKV-specific therapies has led to the use of non-specific drugs. Chloroquine, which is commonly used to treat febrile [...] Read more.
Since 2005, Chikungunya virus (CHIKV) re-emerged and caused numerous outbreaks in the world, and finally, was introduced into the Americas in 2013. The lack of CHIKV-specific therapies has led to the use of non-specific drugs. Chloroquine, which is commonly used to treat febrile illnesses in the tropics, has been shown to inhibit CHIKV replication in vitro. To assess the in vivo effect of chloroquine, two complementary studies were performed: (i) a prophylactic study in a non-human primate model (NHP); and (ii) a curative study “CuraChik”, which was performed during the Reunion Island outbreak in 2006 in a human cohort. Clinical, biological, and immunological data were compared between treated and placebo groups. Acute CHIKV infection was exacerbated in NHPs treated with prophylactic administration of chloroquine. These NHPs displayed a higher viremia and slower viral clearance (p < 0.003). Magnitude of viremia was correlated to the type I IFN response (Rho = 0.8, p < 0.001) and severe lymphopenia (Rho = 0.8, p < 0.0001), while treatment led to a delay in both CHIKV-specific cellular and IgM responses (p < 0.02 and p = 0.04, respectively). In humans, chloroquine treatment did not affect viremia or clinical parameters during the acute stage of the disease (D1 to D14), but affected the levels of C-reactive Protein (CRP), IFNα, IL-6, and MCP1 over time (D1 to D16). Importantly, no positive effect could be detected on prevalence of persistent arthralgia at Day 300. Although inhibitory in vitro, chloroquine as a prophylactic treatment in NHPs enhances CHIKV replication and delays cellular and humoral response. In patients, curative chloroquine treatment during the acute phase decreases the levels of key cytokines, and thus may delay adaptive immune responses, as observed in NHPs, without any suppressive effect on peripheral viral load. Full article
(This article belongs to the Special Issue Advances in Alphavirus Research)
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20 pages, 2046 KiB  
Review
Drug Delivery Strategies for Antivirals against Hepatitis B Virus
by Latavia Singh, Sunaina Indermun, Mershen Govender, Pradeep Kumar, Lisa C. Du Toit, Yahya E. Choonara and Viness Pillay
Viruses 2018, 10(5), 267; https://doi.org/10.3390/v10050267 - 17 May 2018
Cited by 17 | Viewed by 6865
Abstract
Chronic hepatitis B virus (HBV) infection poses a significant health challenge due to associated morbidity and mortality from cirrhosis and hepatocellular cancer that eventually results in the breakdown of liver functionality. Nanotechnology has the potential to play a pivotal role in reducing viral [...] Read more.
Chronic hepatitis B virus (HBV) infection poses a significant health challenge due to associated morbidity and mortality from cirrhosis and hepatocellular cancer that eventually results in the breakdown of liver functionality. Nanotechnology has the potential to play a pivotal role in reducing viral load levels and drug-resistant HBV through drug targeting, thus reducing the rate of evolution of the disease. Apart from tissue targeting, intracellular delivery of a wide range of drugs is necessary to exert a therapeutic action in the affected organelles. This review encompasses the strategies and techniques that have been utilized to target the HBV-infected nuclei in liver hepatocytes, with a significant look at the new insights and most recent advances in drug carriers and their role in anti-HBV therapy. Full article
(This article belongs to the Section Viral Immunology, Vaccines, and Antivirals)
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30 pages, 17088 KiB  
Article
Ectromelia Virus Affects Mitochondrial Network Morphology, Distribution, and Physiology in Murine Fibroblasts and Macrophage Cell Line
by Karolina P. Gregorczyk, Zbigniew Wyżewski, Joanna Szczepanowska, Felix N. Toka, Matylda B. Mielcarska, Magdalena Bossowska-Nowicka, Małgorzata Gieryńska, Anna Boratyńska-Jasińska, Justyna Struzik, Marek G. Niemiałtowski and Lidia Szulc-Dąbrowska
Viruses 2018, 10(5), 266; https://doi.org/10.3390/v10050266 - 16 May 2018
Cited by 16 | Viewed by 6789
Abstract
Mitochondria are multifunctional organelles that participate in numerous processes in response to viral infection, but they are also a target for viruses. The aim of this study was to define subcellular events leading to alterations in mitochondrial morphology and function during infection with [...] Read more.
Mitochondria are multifunctional organelles that participate in numerous processes in response to viral infection, but they are also a target for viruses. The aim of this study was to define subcellular events leading to alterations in mitochondrial morphology and function during infection with ectromelia virus (ECTV). We used two different cell lines and a combination of immunofluorescence techniques, confocal and electron microscopy, and flow cytometry to address subcellular changes following infection. Early in infection of L929 fibroblasts and RAW 264.7 macrophages, mitochondria gathered around viral factories. Later, the mitochondrial network became fragmented, forming punctate mitochondria that co-localized with the progeny virions. ECTV-co-localized mitochondria associated with the cytoskeleton components. Mitochondrial membrane potential, mitochondrial fission–fusion, mitochondrial mass, and generation of reactive oxygen species (ROS) were severely altered later in ECTV infection leading to damage of mitochondria. These results suggest an important role of mitochondria in supplying energy for virus replication and morphogenesis. Presumably, mitochondria participate in transport of viral particles inside and outside of the cell and/or they are a source of membranes for viral envelope formation. We speculate that the observed changes in the mitochondrial network organization and physiology in ECTV-infected cells provide suitable conditions for viral replication and morphogenesis. Full article
(This article belongs to the Special Issue Cytoskeleton in Virus Infections)
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15 pages, 1874 KiB  
Article
Inhibition of Human Immunodeficiency Virus Type 1 Entry by a Keggin Polyoxometalate
by Xiaoli Wang, Jiao Wang, Wenmei Zhang, Boye Li, Ying Zhu, Qin Hu, Yishu Yang, Xiaoguang Zhang, Hong Yan and Yi Zeng
Viruses 2018, 10(5), 265; https://doi.org/10.3390/v10050265 - 16 May 2018
Cited by 12 | Viewed by 4384
Abstract
Here, we report the anti-human immunodeficiency virus (HIV) potency and underlying mechanisms of a Keggin polyoxometalate (PT-1, K6HPTi2W10O40). Our findings showed that PT-1 exhibited highly potent effects against a diverse group of HIV type 1 [...] Read more.
Here, we report the anti-human immunodeficiency virus (HIV) potency and underlying mechanisms of a Keggin polyoxometalate (PT-1, K6HPTi2W10O40). Our findings showed that PT-1 exhibited highly potent effects against a diverse group of HIV type 1 (HIV-1) strains and displayed low cytotoxicity and genotoxicity. The time-addition assay revealed that PT-1 acted at an early stage of infection, and these findings were supported by the observation that PT-1 had more potency against Env-pseudotyped virus than vesicular stomatitis virus glycoprotein (VSVG) pseudotyped virus. Surface plasmon resonance binding assays and flow cytometry analysis showed that PT-1 blocked the gp120 binding site in the CD4 receptor. Moreover, PT-1 bound directly to gp41 NHR (N36 peptide), thereby interrupting the core bundle formation of gp41. In conclusion, our data suggested that PT-1 may be developed as a new anti-HIV-1 agent through its effects on entry inhibition. Full article
(This article belongs to the Section Viral Immunology, Vaccines, and Antivirals)
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18 pages, 1675 KiB  
Article
Strain-Specific Antagonism of the Human H1N1 Influenza A Virus against Equine Tetherin
by Meiyue Wang, Zhenyu Zhang and Xiaojun Wang
Viruses 2018, 10(5), 264; https://doi.org/10.3390/v10050264 - 16 May 2018
Cited by 7 | Viewed by 3974
Abstract
Tetherin/BST-2/CD317 is an interferon-induced host restriction factor that can block the budding of enveloped viruses by tethering them to the cell surface. Many viruses use certain proteins to counteract restriction by tetherin from their natural hosts, but not from other species. The influenza [...] Read more.
Tetherin/BST-2/CD317 is an interferon-induced host restriction factor that can block the budding of enveloped viruses by tethering them to the cell surface. Many viruses use certain proteins to counteract restriction by tetherin from their natural hosts, but not from other species. The influenza A virus (FLUAV) has a wide range of subtypes with different host tropisms. Human tetherin (huTHN) has been reported to restrict only specific FLUAV strains and the viral hemagglutinin (HA) and neuraminidase (NA) genes determine the sensitivity to huTHN. Whether tetherins from other hosts can block human FLUAV is still unknown. Here, we evaluate the impact of equine tetherin (eqTHN) and huTHN on the replication of A/Sichuan/1/2009 (H1N1) and A/equine/Xinjiang/1/2007 (H3N8) strains. Our results show that eqTHN had higher restriction activity towards both viruses, and its shorter cytoplasmic tail contributed to that activity. We further demonstrated that HA and NA of A/Hamburg/4/2009 (H1N1) could counteract eqTHN. Notably, our results indicate that four amino acids, 13T and 49L of HA and 32T and 80V of NA, were involved in blocking the restriction activity of eqTHN. These findings reveal interspecies restriction by eqTHN towards FLUAV, and the role of the HA and NA proteins in overcoming this restriction. Full article
(This article belongs to the Special Issue What’s New with Flu?)
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12 pages, 1211 KiB  
Article
Encapsidated Host Factors in Alphavirus Particles Influence Midgut Infection of Aedes aegypti
by David Mackenzie-Liu, Kevin J. Sokoloski, Sarah Purdy and Richard W. Hardy
Viruses 2018, 10(5), 263; https://doi.org/10.3390/v10050263 - 16 May 2018
Cited by 8 | Viewed by 3902
Abstract
Transmission of mosquito-borne viruses requires the efficient infection of both a permissive vertebrate host and a competent mosquito vector. The infectivity of Sindbis virus (SINV), the type species of the Alphavirus genus, is influenced by both the original and new host cell. We [...] Read more.
Transmission of mosquito-borne viruses requires the efficient infection of both a permissive vertebrate host and a competent mosquito vector. The infectivity of Sindbis virus (SINV), the type species of the Alphavirus genus, is influenced by both the original and new host cell. We have shown that infection of vertebrate cells by SINV, chikungunya virus (CHIKV), and Ross River virus (RRV) produces two subpopulations of virus particles separable based on density. In contrast, a single population of viral particles is produced by mosquito cells. Previous studies demonstrated that the denser vertebrate-derived particles and the mosquito-derived particles contain components of the small subunit of the host cell ribosome, whereas the less dense vertebrate-derived particles do not. Infection of mice with RRV showed that both particle subpopulations are produced in an infected vertebrate, but in a tissue specific manner with serum containing only the less dense version of the virus particles. Previous infectivity studies using SINV particles have shown that the denser particles (SINVHeavy) and mosquito derived particles SINVC6/36 are significantly more infectious in vertebrate cells than the less dense vertebrate derived particles (SINVLight). The current study shows that SINVLight particles, initiate the infection of the mosquito midgut more efficiently than SINVHeavy particles and that this enhanced infectivity is associated with an exacerbated immune response to SINVLight infection in midgut tissues. The enhanced infection of SINVLight is specific to the midgut as intrathoracically injected virus do not exhibit the same fitness advantage. Together, our data indicate a biologically significant role for the SINVLight subpopulation in the efficient transmission from infected vertebrates to the mosquito vector. Full article
(This article belongs to the Special Issue Advances in Alphavirus Research)
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14 pages, 11641 KiB  
Article
Gp120 V5 Is Targeted by the First Wave of Sequential Neutralizing Antibodies in SHIVSF162P3N-Infected Rhesus Macaques
by Manxue Jia, Hong Lu, Xiang-Peng Kong, Cecilia Cheng-Mayer and Xueling Wu
Viruses 2018, 10(5), 262; https://doi.org/10.3390/v10050262 - 16 May 2018
Cited by 2 | Viewed by 3229
Abstract
Simian-human immunodeficiency virus (SHIV) infection provides a relevant animal model to study HIV-1 neutralization breadth. With previously identified SHIVSF162P3N infected rhesus macaques that did or did not develop neutralization breadth, we characterized the transmitted/founder viruses and initial autologous/homologous neutralizing antibodies in these [...] Read more.
Simian-human immunodeficiency virus (SHIV) infection provides a relevant animal model to study HIV-1 neutralization breadth. With previously identified SHIVSF162P3N infected rhesus macaques that did or did not develop neutralization breadth, we characterized the transmitted/founder viruses and initial autologous/homologous neutralizing antibodies in these animals. The plasma viral load and blood CD4 count did not distinguish macaques with and without breadth, and only one tested homologous envelope clone revealed a trend for macaques with breadth to favor an early homologous response. In two macaques with breadth, GB40 and FF69, infected with uncloned SHIVSF162P3N, multiple viral variants were transmitted, and the transmitted variants were not equal in neutralization sensitivity. The targets of initial autologous neutralizing antibodies, arising between 10 and 20 weeks post infection, were mapped to N462 glycan and G460a in gp120 V5 in GB40 and FF69, respectively. Although it is unclear whether these targets are related to later neutralization breadth development, the G460a target but not N462 glycan appeared more common in macaques with breadth than those without. Longitudinal plasmas revealed 2–3 sequential waves of neutralizing antibodies in macaques with breadth, implicating that 3 sequential envelope variants, if not more, may be required for the broadening of HIV-1 neutralizing antibodies. Full article
(This article belongs to the Special Issue HIV Vaccines)
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16 pages, 1922 KiB  
Review
Properties and Functions of Feline Immunodeficiency Virus Gag Domains in Virion Assembly and Budding
by Silvia A. González and José L. Affranchino
Viruses 2018, 10(5), 261; https://doi.org/10.3390/v10050261 - 16 May 2018
Cited by 8 | Viewed by 4277
Abstract
Feline immunodeficiency virus (FIV) is an important cat pathogen worldwide whose biological and pathophysiological properties resemble those of human immunodeficiency virus type 1 (HIV-1). Therefore, the study of FIV not only benefits its natural host but is also useful for the development of [...] Read more.
Feline immunodeficiency virus (FIV) is an important cat pathogen worldwide whose biological and pathophysiological properties resemble those of human immunodeficiency virus type 1 (HIV-1). Therefore, the study of FIV not only benefits its natural host but is also useful for the development of antiviral strategies directed against HIV-1 infections in humans. FIV assembly results from the multimerization of a single but complex viral polypeptide, the Gag precursor. In this review, we will first give an overview of the current knowledge of the proteins encoded by the FIV pol, env, rev, vif, and orf-A genes, and then we will describe and discuss in detail the critical roles that each of the FIV Gag domains plays in virion morphogenesis. Since retroviral assembly is an attractive target for therapeutic interventions, gaining a better understanding of this process is highly desirable. Full article
(This article belongs to the Special Issue Nonprimate Lentivirus)
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14 pages, 6996 KiB  
Article
Blackcurrant Leaf Chlorosis Associated Virus: Evidence of the Presence of Circular RNA during Infections
by Delano James, James Phelan and Daniel Sanderson
Viruses 2018, 10(5), 260; https://doi.org/10.3390/v10050260 - 15 May 2018
Cited by 5 | Viewed by 3860
Abstract
Blackcurrant leaf chlorosis associated virus (BCLCaV) was detected recently by next-generation sequencing (NGS) and a new and distinct species in the genus Idaeovirus was proposed. Analysis of NGS-derived paired-end reads revealed the existence of bridge reads encompassing the 3′-terminus and 5′-terminus of RNA-2 [...] Read more.
Blackcurrant leaf chlorosis associated virus (BCLCaV) was detected recently by next-generation sequencing (NGS) and a new and distinct species in the genus Idaeovirus was proposed. Analysis of NGS-derived paired-end reads revealed the existence of bridge reads encompassing the 3′-terminus and 5′-terminus of RNA-2 or RNA-3 of BCLCaV. The full RNA-2 or RNA-3 could be amplified using outward facing or abutting primers; also, RNA-2/RNA-3 could be detected even after three consecutive RNase R enzyme treatments, with denaturation at 95 °C preceding each digestion. Evidence was obtained indicating that there are circular forms of BCLCaV RNA-2 and RNA-3. Full article
(This article belongs to the Special Issue Fruit Tree Viruses and Viroids)
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12 pages, 1594 KiB  
Article
Zika Virus Induces Autophagy in Human Umbilical Vein Endothelial Cells
by Haoran Peng, Bin Liu, Toure Doueu Yves, Yanhua He, Shijie Wang, Hailin Tang, Hao Ren, Ping Zhao, Zhongtian Qi and Zhaoling Qin
Viruses 2018, 10(5), 259; https://doi.org/10.3390/v10050259 - 15 May 2018
Cited by 58 | Viewed by 6066
Abstract
Autophagy is a common strategy for cell protection; however, some viruses can in turn adopt cellular autophagy to promote viral replication. Zika virus (ZIKV) is the pathogen that causes Zika viral disease, and it is a mosquito-borne virus. However, its pathogenesis, especially the [...] Read more.
Autophagy is a common strategy for cell protection; however, some viruses can in turn adopt cellular autophagy to promote viral replication. Zika virus (ZIKV) is the pathogen that causes Zika viral disease, and it is a mosquito-borne virus. However, its pathogenesis, especially the interaction between ZIKV and target cells during the early stages of infection, is still unclear. In this study, we demonstrate that infecting human umbilical vein endothelial cells (HUVEC) with ZIKV triggers cellular autophagy. We observed both an increase in the conversion of LC3-I to LC3-II and increased accumulation of fluorescent cells with LC3 dots, which are considered to be the two key indicators of autophagy. The ratio of LC3-II/GAPDH in each group was significantly increased at different times after ZIKV infection at different MOIs, indicating that the production of lipidated LC3-II increased. Moreover, both the ratio of LC3-II/GAPDH and the expression of viral NS3 protein increased with increasing time of viral infection. The expression level of p62 decreased gradually from 12 h post-infection. Expression profile of double fluorescent protein labelling LC3 indicated that the autophagy induced by ZIKV infection was a complete process. We further investigated the role of autophagy in ZIKV replication. We demonstrated that either the treatment with inhibitors of autophagosomes formation or short hairpin RNA targeting the Beclin-1 gene, which is critical for the formation of autophagosomes, significantly reduced viral production. Taken together, our results indicate that ZIKV infection induces autophagy of HUVEC, and inhibition of ZIKV-induced autophagy restrains viral replication. Full article
(This article belongs to the Section Animal Viruses)
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10 pages, 4167 KiB  
Article
CRISPR/Cas9 Mutagenesis of UL21 in Multiple Strains of Herpes Simplex Virus Reveals Differential Requirements for pUL21 in Viral Replication
by Renée L. Finnen and Bruce W. Banfield
Viruses 2018, 10(5), 258; https://doi.org/10.3390/v10050258 - 15 May 2018
Cited by 23 | Viewed by 5284
Abstract
Studies from multiple laboratories using different strains or species of herpes simplex virus (HSV) with deletions in UL21 have yielded conflicting results regarding the necessity of pUL21 in HSV infection. To resolve this discrepancy, we utilized CRISPR/Cas9 mutagenesis to isolate pUL21 deficient viruses [...] Read more.
Studies from multiple laboratories using different strains or species of herpes simplex virus (HSV) with deletions in UL21 have yielded conflicting results regarding the necessity of pUL21 in HSV infection. To resolve this discrepancy, we utilized CRISPR/Cas9 mutagenesis to isolate pUL21 deficient viruses in multiple HSV backgrounds, and performed a side-by-side comparison of the cell-to-cell spread and replication phenotypes of these viruses. These analyses confirmed previous studies implicating the involvement of pUL21 in cell-to-cell spread of HSV. Cell-to-cell spread of HSV-2 was more greatly affected by the lack of pUL21 than HSV-1, and strain-specific differences in the requirement for pUL21 in cell-to-cell spread were also noted. HSV-2 strain 186 lacking pUL21 was particularly crippled in both cell-to-cell spread and viral replication in non-complementing cells, in comparison to other HSV strains lacking pUL21, suggesting that the strict requirement for pUL21 by strain 186 may not be representative of the HSV-2 species as a whole. This work highlights CRISPR/Cas9 technology as a useful tool for rapidly constructing deletion mutants of alphaherpesviruses, regardless of background strain, and should find great utility whenever strain-specific differences need to be investigated. Full article
(This article belongs to the Special Issue Applications of CRISPR Technology in Virology 2018)
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23 pages, 3438 KiB  
Article
Time-Course Microarray Analysis Reveals Differences between Transcriptional Changes in Tomato Leaves Triggered by Mild and Severe Variants of Potato Spindle Tuber Viroid
by Aneta Więsyk, Roksana Iwanicka-Nowicka, Anna Fogtman, Włodzimierz Zagórski-Ostoja and Anna Góra-Sochacka
Viruses 2018, 10(5), 257; https://doi.org/10.3390/v10050257 - 15 May 2018
Cited by 24 | Viewed by 5171
Abstract
Viroids are small non-capsidated non-coding RNA replicons that utilize host factors for efficient propagation and spread through the entire plant. They can incite specific disease symptoms in susceptible plants. To better understand viroid-plant interactions, we employed microarray analysis to observe the changes of [...] Read more.
Viroids are small non-capsidated non-coding RNA replicons that utilize host factors for efficient propagation and spread through the entire plant. They can incite specific disease symptoms in susceptible plants. To better understand viroid-plant interactions, we employed microarray analysis to observe the changes of gene expression in “Rutgers” tomato leaves in response to the mild (M) and severe (S23) variants of potato spindle tuber viroid (PSTVd). The changes were analyzed over a time course of viroid infection development: (i) the pre-symptomatic stage; (ii) early symptoms; (iii) full spectrum of symptoms and (iv) the so-called ‘recovery’ stage, when stem regrowth was observed in severely affected plants. Gene expression profiles differed depending on stage of infection and variant. In S23-infected plants, the expression of over 3000 genes was affected, while M-infected plants showed 3-fold fewer differentially expressed genes, only 20% of which were specific to the M variant. The differentially expressed genes included many genes related to stress; defense; hormone metabolism and signaling; photosynthesis and chloroplasts; cell wall; RNA regulation, processing and binding; protein metabolism and modification and others. The expression levels of several genes were confirmed by nCounter analysis. Full article
(This article belongs to the Special Issue Viroid-2018: International Conference on Viroids and Viroid-Like RNAs)
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19 pages, 3303 KiB  
Conference Report
Bioinformatics Meets Virology: The European Virus Bioinformatics Center’s Second Annual Meeting
by Bashar Ibrahim, Ksenia Arkhipova, Arno C. Andeweg, Susana Posada-Céspedes, François Enault, Arthur Gruber, Eugene V. Koonin, Anne Kupczok, Philippe Lemey, Alice C. McHardy, Dino P. McMahon, Brett E. Pickett, David L. Robertson, Richard H. Scheuermann, Alexandra Zhernakova, Mark P. Zwart, Alexander Schönhuth, Bas E. Dutilh and Manja Marz
Viruses 2018, 10(5), 256; https://doi.org/10.3390/v10050256 - 14 May 2018
Cited by 5 | Viewed by 9641
Abstract
The Second Annual Meeting of the European Virus Bioinformatics Center (EVBC), held in Utrecht, Netherlands, focused on computational approaches in virology, with topics including (but not limited to) virus discovery, diagnostics, (meta-)genomics, modeling, epidemiology, molecular structure, evolution, and viral ecology. The goals of [...] Read more.
The Second Annual Meeting of the European Virus Bioinformatics Center (EVBC), held in Utrecht, Netherlands, focused on computational approaches in virology, with topics including (but not limited to) virus discovery, diagnostics, (meta-)genomics, modeling, epidemiology, molecular structure, evolution, and viral ecology. The goals of the Second Annual Meeting were threefold: (i) to bring together virologists and bioinformaticians from across the academic, industrial, professional, and training sectors to share best practice; (ii) to provide a meaningful and interactive scientific environment to promote discussion and collaboration between students, postdoctoral fellows, and both new and established investigators; (iii) to inspire and suggest new research directions and questions. Approximately 120 researchers from around the world attended the Second Annual Meeting of the EVBC this year, including 15 renowned international speakers. This report presents an overview of new developments and novel research findings that emerged during the meeting. Full article
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18 pages, 1671 KiB  
Review
A Review of the Ongoing Research on Zika Virus Treatment
by Suely Da Silva, Daniel Oliveira Silva Martins and Ana Carolina Gomes Jardim
Viruses 2018, 10(5), 255; https://doi.org/10.3390/v10050255 - 14 May 2018
Cited by 39 | Viewed by 8842
Abstract
The Zika fever is an arboviral disease resulting from the infection with Zika virus (ZIKV). The virus is transmitted to humans by the bite of Aedes mosquitos, mainly Aedes aegypti and Aedes albopictus. ZIKV has been detected for decades in African and [...] Read more.
The Zika fever is an arboviral disease resulting from the infection with Zika virus (ZIKV). The virus is transmitted to humans by the bite of Aedes mosquitos, mainly Aedes aegypti and Aedes albopictus. ZIKV has been detected for decades in African and Asian regions and, since 2007, has spread to other continents; among them, infections are most reported in the Americas. This can be explained by the presence of vectors in highly populated and tropical regions where people are susceptible to contamination. ZIKV has been considered by the World Health Organization a serious public health problem because of the increasing number of cases of congenital malformation and neurological disorders related to its infection, such as microcephaly, Guillain–Barré syndrome, meningoencephalitis, and myelitis. There is no vaccine or specific antiviral against ZIKV. The infection is best prevented by avoiding mosquito bite, and the treatment of infected patients is palliative. In this context, the search for efficient antivirals is necessary but remains challenging. Here, we aim to review the molecules that have been described to interfere with ZIKV life cycle and discuss their potential use in ZIKV therapy. Full article
(This article belongs to the Section Viral Immunology, Vaccines, and Antivirals)
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20 pages, 5366 KiB  
Article
Two Novel Hypovirulence-Associated Mycoviruses in the Phytopathogenic Fungus Botrytis cinerea: Molecular Characterization and Suppression of Infection Cushion Formation
by Fangmin Hao, Ting Ding, Mingde Wu, Jing Zhang, Long Yang, Weidong Chen and Guoqing Li
Viruses 2018, 10(5), 254; https://doi.org/10.3390/v10050254 - 13 May 2018
Cited by 57 | Viewed by 6761
Abstract
Botrytis cinerea is a necrotrophic fungus causing disease on many important agricultural crops. Two novel mycoviruses, namely Botrytis cinerea hypovirus 1 (BcHV1) and Botrytis cinerea fusarivirus 1 (BcFV1), were fully sequenced. The genome of BcHV1 is 10,214 nt long excluding a poly-A tail [...] Read more.
Botrytis cinerea is a necrotrophic fungus causing disease on many important agricultural crops. Two novel mycoviruses, namely Botrytis cinerea hypovirus 1 (BcHV1) and Botrytis cinerea fusarivirus 1 (BcFV1), were fully sequenced. The genome of BcHV1 is 10,214 nt long excluding a poly-A tail and possesses one large open reading frame (ORF) encoding a polyprotein possessing several conserved domains including RNA-dependent RNA polymerase (RdRp), showing homology to hypovirus-encoded polyproteins. Phylogenetic analysis indicated that BcHV1 may belong to the proposed genus Betahypovirus in the viral family Hypoviridae. The genome of BcFV1 is 8411 nt in length excluding the poly A tail and theoretically processes two major ORFs, namely ORF1 and ORF2. The larger ORF1 encoded polypeptide contains protein domains of an RdRp and a viral helicase, whereas the function of smaller ORF2 remains unknown. The BcFV1 was phylogenetically clustered with other fusariviruses forming an independent branch, indicating BcFV1 was a member in Fusariviridae. Both BcHV1 and BcFV1 were capable of being transmitted horizontally through hyphal anastomosis. Infection by BcHV1 alone caused attenuated virulence without affecting mycelial growth, significantly inhibited infection cushion (IC) formation, and altered expression of several IC-formation-associated genes. However, wound inoculation could fully rescue the virulence phenotype of the BcHV1 infected isolate. These results indicate the BcHV1-associated hypovirulence is caused by the viral influence on IC-formation-associated pathways. Full article
(This article belongs to the Special Issue Mycoviruses)
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15 pages, 854 KiB  
Article
Detection of Specific ZIKV IgM in Travelers Using a Multiplexed Flavivirus Microsphere Immunoassay
by Carmel T. Taylor, Ian M. Mackay, Jamie L. McMahon, Sarah L. Wheatley, Peter R. Moore, Mitchell J. Finger, Glen R. Hewitson and Frederick A. Moore
Viruses 2018, 10(5), 253; https://doi.org/10.3390/v10050253 - 12 May 2018
Cited by 13 | Viewed by 5927
Abstract
Zika virus (ZIKV) has spread widely in the Pacific and recently throughout the Americas. Unless detected by RT-PCR, confirming an acute ZIKV infection can be challenging. We developed and validated a multiplexed flavivirus immunoglobulin M (IgM) microsphere immunoassay (flaviMIA) which can differentiate ZIKV-specific [...] Read more.
Zika virus (ZIKV) has spread widely in the Pacific and recently throughout the Americas. Unless detected by RT-PCR, confirming an acute ZIKV infection can be challenging. We developed and validated a multiplexed flavivirus immunoglobulin M (IgM) microsphere immunoassay (flaviMIA) which can differentiate ZIKV-specific IgM from that due to other flavivirus infections in humans. The flaviMIA bound 12 inactivated flavivirus antigens, including those from ZIKV and yellow fever virus (YFV), to distinct anti-flavivirus antibody coupled beads. These beads were used to interrogate sera from patients with suspected ZIKV infection following travel to relevant countries. FlaviMIA results were validated by comparison to the ZIKV plaque reduction neutralization test (PRNT). The results highlight the complexity of serological ZIKV diagnosis, particularly in patients previously exposed to or vaccinated against other flaviviruses. We confirmed 99 patients with ZIKV infection by a combination of RT-PCR and serology. Importantly, ZIKV antibodies could be discriminated from those ascribed to other flavivirus infections. Serological results were sometimes confounded by the presence of pre-existing antibodies attributed to previous flavivirus infection or vaccination. Where RT-PCR results were negative, testing of appropriately timed paired sera was necessary to demonstrate seroconversion or differentiation of recent from past infection with or exposure to ZIKV. Full article
(This article belongs to the Special Issue New Advances on Zika Virus Research)
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15 pages, 4897 KiB  
Article
Genome Sequences of Akhmeta Virus, an Early Divergent Old World Orthopoxvirus
by Jinxin Gao, Crystal Gigante, Ekaterine Khmaladze, Pengbo Liu, Shiyuyun Tang, Kimberly Wilkins, Kun Zhao, Whitni Davidson, Yoshinori Nakazawa, Giorgi Maghlakelidze, Marika Geleishvili, Maka Kokhreidze, Darin S. Carroll, Ginny Emerson and Yu Li
Viruses 2018, 10(5), 252; https://doi.org/10.3390/v10050252 - 12 May 2018
Cited by 36 | Viewed by 5897
Abstract
Annotated whole genome sequences of three isolates of the Akhmeta virus (AKMV), a novel species of orthopoxvirus (OPXV), isolated from the Akhmeta and Vani regions of the country Georgia, are presented and discussed. The AKMV genome is similar in genomic content and structure [...] Read more.
Annotated whole genome sequences of three isolates of the Akhmeta virus (AKMV), a novel species of orthopoxvirus (OPXV), isolated from the Akhmeta and Vani regions of the country Georgia, are presented and discussed. The AKMV genome is similar in genomic content and structure to that of the cowpox virus (CPXV), but a lower sequence identity was found between AKMV and Old World OPXVs than between other known species of Old World OPXVs. Phylogenetic analysis showed that AKMV diverged prior to other Old World OPXV. AKMV isolates formed a monophyletic clade in the OPXV phylogeny, yet the sequence variability between AKMV isolates was higher than between the monkeypox virus strains in the Congo basin and West Africa. An AKMV isolate from Vani contained approximately six kb sequence in the left terminal region that shared a higher similarity with CPXV than with other AKMV isolates, whereas the rest of the genome was most similar to AKMV, suggesting recombination between AKMV and CPXV in a region containing several host range and virulence genes. Full article
(This article belongs to the Section Animal Viruses)
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10 pages, 1945 KiB  
Article
Clostridium perfringens Virulent Bacteriophage CPS2 and Its Thermostable Endolysin LysCPS2
by Eunsu Ha, Bokyung Son and Sangryeol Ryu
Viruses 2018, 10(5), 251; https://doi.org/10.3390/v10050251 - 11 May 2018
Cited by 48 | Viewed by 6730
Abstract
Clostridium perfringens is one of the most common causes of food-borne illness. The increasing prevalence of multidrug-resistant bacteria requires the development of alternatives to typical antimicrobial treatments. Here, we isolated and characterized a C. perfringens-specific virulent bacteriophage CPS2 from chicken feces. The [...] Read more.
Clostridium perfringens is one of the most common causes of food-borne illness. The increasing prevalence of multidrug-resistant bacteria requires the development of alternatives to typical antimicrobial treatments. Here, we isolated and characterized a C. perfringens-specific virulent bacteriophage CPS2 from chicken feces. The CPS2 phage contains a 17,961 bp double-stranded DNA genome with 25 putative ORFs, and belongs to the Picovirinae, subfamily of Podoviridae. Bioinformatic analysis of the CPS2 genome revealed a putative endolysin, LysCPS2, which is homologous to the endolysin of Clostridium phage phiZP2 and phiCP7R. The enzyme showed strong lytic activity against C. perfringens with optimum conditions at pH 7.5–10, 25–65 °C, and over a broad range of NaCl concentrations. Interestingly, LysCPS2 was found to be highly thermostable, with up to 30% of its lytic activity remaining after 10 min of incubation at 95 °C. The cell wall binding domain in the C-terminal region of LysCPS2 showed a binding spectrum specific to C. perfringens strains. This is the first report to characterize highly thermostable endolysin isolated from virulent C. perfringens bacteriophage. The enzyme can be used as an alternative biocontrol and detection agent against C. perfringens. Full article
(This article belongs to the Special Issue Biotechnological Applications of Phage and Phage-Derived Proteins)
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21 pages, 2798 KiB  
Review
Single Viruses on the Fluorescence Microscope: Imaging Molecular Mobility, Interactions and Structure Sheds New Light on Viral Replication
by Nagma Parveen, Doortje Borrenberghs, Susana Rocha and Jelle Hendrix
Viruses 2018, 10(5), 250; https://doi.org/10.3390/v10050250 - 10 May 2018
Cited by 21 | Viewed by 8901
Abstract
Viruses are simple agents exhibiting complex reproductive mechanisms. Decades of research have provided crucial basic insights, antiviral medication and moderately successful gene therapy trials. The most infectious viral particle is, however, not always the most abundant one in a population, questioning the utility [...] Read more.
Viruses are simple agents exhibiting complex reproductive mechanisms. Decades of research have provided crucial basic insights, antiviral medication and moderately successful gene therapy trials. The most infectious viral particle is, however, not always the most abundant one in a population, questioning the utility of classic ensemble-averaging virology. Indeed, viral replication is often not particularly efficient, prone to errors or containing parallel routes. Here, we review different single-molecule sensitive fluorescence methods that we employ routinely to investigate viruses. We provide a brief overview of the microscopy hardware needed and discuss the different methods and their application. In particular, we review how we applied (i) single-molecule Förster resonance energy transfer (smFRET) to probe the subviral human immunodeficiency virus (HIV-1) integrase (IN) quaternary structure; (ii) single particle tracking to study interactions of the simian virus 40 with membranes; (iii) 3D confocal microscopy and smFRET to quantify the HIV-1 pre-integration complex content and quaternary structure; (iv) image correlation spectroscopy to quantify the cytosolic HIV-1 Gag assembly, and finally; (v) super-resolution microscopy to characterize the interaction of HIV-1 with tetherin during assembly. We hope this review is an incentive for setting up and applying similar single-virus imaging studies in daily virology practice. Full article
(This article belongs to the Special Issue Application of Advanced Imaging to the Study of Virus Replication)
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12 pages, 5536 KiB  
Article
Thiol-Activated Hydrogen Sulfide Donors Antiviral and Anti-Inflammatory Activity in Respiratory Syncytial Virus Infection
by Nikolay Bazhanov, Teodora Ivanciuc, Haotian Wu, Matteo Garofalo, Jianming Kang, Ming Xian and Antonella Casola
Viruses 2018, 10(5), 249; https://doi.org/10.3390/v10050249 - 10 May 2018
Cited by 31 | Viewed by 5133
Abstract
We have recently shown that endogenous hydrogen sulfide (H2S), an important cellular gaseous mediator, exerts an antiviral and anti-inflammatory activity in vitro and in vivo, and that exogenous H2S delivered via the synthetic H2S-releasing compound GYY4137 also [...] Read more.
We have recently shown that endogenous hydrogen sulfide (H2S), an important cellular gaseous mediator, exerts an antiviral and anti-inflammatory activity in vitro and in vivo, and that exogenous H2S delivered via the synthetic H2S-releasing compound GYY4137 also has similar properties. In this study, we sought to extend our findings to a novel class of H2S donors, thiol-activated gem-dithiol-based (TAGDDs). In an in vitro model of human respiratory syncytial virus (RSV) infection, TAGDD-1 treatment significantly reduced viral replication, even when added up to six hours after infection. Using a mouse model of RSV infection, intranasal delivery of TAGDD-1 to infected mice significantly reduced viral replication and lung inflammation, markedly improving clinical disease parameters and pulmonary dysfunction, compared to vehicle treated controls. Overall our results indicate that this novel synthetic class of H2S-releasing compounds exerts antiviral and anti-inflammatory activity in the context of RSV infection and represents a potential novel pharmacological approach to ameliorate viral-induced lung disease. Full article
(This article belongs to the Section Viral Immunology, Vaccines, and Antivirals)
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18 pages, 7623 KiB  
Article
Molecular and Clinical Characterization of Chikungunya Virus Infections in Southeast Mexico
by Kame A. Galán-Huerta, Erik Martínez-Landeros, Juan L. Delgado-Gallegos, Sandra Caballero-Sosa, Iliana R. Malo-García, Ildefonso Fernández-Salas, Javier Ramos-Jiménez and Ana M. Rivas-Estilla
Viruses 2018, 10(5), 248; https://doi.org/10.3390/v10050248 - 9 May 2018
Cited by 12 | Viewed by 5704
Abstract
Chikungunya fever is an arthropod-borne infection caused by Chikungunya virus (CHIKV). Even though clinical features of Chikungunya fever in the Mexican population have been described before, there is no detailed information. The aim of this study was to perform a full description of [...] Read more.
Chikungunya fever is an arthropod-borne infection caused by Chikungunya virus (CHIKV). Even though clinical features of Chikungunya fever in the Mexican population have been described before, there is no detailed information. The aim of this study was to perform a full description of the clinical features in confirmed Chikungunya-infected patients and describe the molecular epidemiology of CHIKV. We evaluated febrile patients who sought medical assistance in Tapachula, Chiapas, Mexico, from June through July 2015. Infection was confirmed with molecular and serological methods. Viruses were isolated and the E1 gene was sequenced. Phylogeny reconstruction was inferred using maximum-likelihood and maximum clade credibility approaches. We studied 52 patients with confirmed CHIKV infection. They were more likely to have wrist, metacarpophalangeal, and knee arthralgia. Two combinations of clinical features were obtained to differentiate between Chikungunya fever and acute undifferentiated febrile illness. We obtained 10 CHIKV E1 sequences that grouped with the Asian lineage. Seven strains diverged from the formerly reported. Patients infected with the divergent CHIKV strains showed a broader spectrum of clinical manifestations. We defined the complete clinical features of Chikungunya fever in patients from Southeastern Mexico. Our results demonstrate co-circulation of different CHIKV strains in the state of Chiapas. Full article
(This article belongs to the Special Issue 6th Pan-American Dengue Research Network Meeting)
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