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1.
Lakdawala SS Lamirande EW Suguitan AL Wang W Santos CP Vogel L Matsuoka Y Lindsley WG Jin H Subbarao K 《PLoS pathogens》2011,7(12):e1002443
The epidemiological success of pandemic and epidemic influenza A viruses relies on the ability to transmit efficiently from person-to-person via respiratory droplets. Respiratory droplet (RD) transmission of influenza viruses requires efficient replication and release of infectious influenza particles into the air. The 2009 pandemic H1N1 (pH1N1) virus originated by reassortment of a North American triple reassortant swine (TRS) virus with a Eurasian swine virus that contributed the neuraminidase (NA) and M gene segments. Both the TRS and Eurasian swine viruses caused sporadic infections in humans, but failed to spread from person-to-person, unlike the pH1N1 virus. We evaluated the pH1N1 and its precursor viruses in a ferret model to determine the contribution of different viral gene segments on the release of influenza virus particles into the air and on the transmissibility of the pH1N1 virus. We found that the Eurasian-origin gene segments contributed to efficient RD transmission of the pH1N1 virus likely by modulating the release of influenza viral RNA-containing particles into the air. All viruses replicated well in the upper respiratory tract of infected ferrets, suggesting that factors other than viral replication are important for the release of influenza virus particles and transmission. Our studies demonstrate that the release of influenza viral RNA-containing particles into the air correlates with increased NA activity. Additionally, the pleomorphic phenotype of the pH1N1 virus is dependent upon the Eurasian-origin gene segments, suggesting a link between transmission and virus morphology. We have demonstrated that the viruses are released into exhaled air to varying degrees and a constellation of genes influences the transmissibility of the pH1N1 virus. 相似文献
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Suspensions of orthomyxo- and paramyxoviruses are composed of pleomorphic particles ranging from large filaments to small spheres. Influenza and Sendai viruses were separated according to size by gel filtration and the induction of luminol-dependent chemiluminescence (CL) by particles of similar size was studied in suspensions of mouse spleen cells known to contain phagocytes. CL reflects the generation by the cells of reactive oxygen species. CL induction decreased with particle size for both viruses. Compared with small spheres, large influenza filaments were approximately 10 times as efficient in activating cellular light emission while the ratio between large and small Sendai viruses was 3:1. Small Sendai virus particles were also less efficient in lysing red cells and had lower neuraminidase activity. By contrast, with influenza virus, only neuraminidase and not the hemolytic activity decreased with the virus size. When influenza virus filaments were broken into smaller particles by sonication, the capacity to induce chemiluminescence dropped markedly while the hemolytic and hemagglutinating activities increased and neuraminidase activity remained unaltered. These results suggest that the presentation of influenza virus hemagglutinin and neuraminidase glycoproteins in a large particle, leading to extensive receptor crosslinking, may be an important factor in the efficient activation of CL by filamentous influenza virus. We suggest that radical generation as reflected in cellular CL may relate to the toxic in vivo effects that contribute to the pathogenesis of influenza and infections with paramyxoviruses. 相似文献
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《Free radical research》2013,47(1-3):11-22
Suspensions of orthomyxo- and paramyxoviruses are composed of pleomorphic particles ranging from large filaments to small spheres. Influenza and Sendai viruses were separated according to size by gel filtration and the induction of luminol-dependent chemiluminescence (CL) by particles of similar size was studied in suspensions of mouse spleen cells known to contain phagocytes. CL reflects the generation by the cells of reactive oxygen species. CL induction decreased with particle size for both viruses. Compared with small spheres, large influenza filaments were approximately 10 times as efficient in activating cellular light emission while the ratio between large and small Sendai viruses was 3:1. Small Sendai virus particles were also less efficient in lysing red cells and had lower neuraminidase activity. By contrast, with influenza virus, only neuraminidase and not the hemolytic activity decreased with the virus size. When influenza virus filaments were broken into smaller particles by sonication, the capacity to induce chemiluminescence dropped markedly while the hemolytic and hemagglutinating activities increased and neuraminidase activity remained unaltered. These results suggest that the presentation of influenza virus hemagglutinin and neuraminidase glycoproteins in a large particle, leading to extensive receptor crosslinking, may be an important factor in the efficient activation of CL by filamentous influenza virus. We suggest that radical generation as reflected in cellular CL may relate to the toxic in vivo effects that contribute to the pathogenesis of influenza and infections with paramyxoviruses. 相似文献
4.
Kortney M. Gustin Jacqueline M. Katz Terrence M. Tumpey Taronna R. Maines 《Journal of virology》2013,87(14):7864-7873
Influenza viruses pose a major public health burden to communities around the world by causing respiratory infections that can be highly contagious and spread rapidly through the population. Despite extensive research on influenza viruses, the modes of transmission occurring most often among humans are not entirely clear. Contributing to this knowledge gap is the lack of an understanding of the levels of infectious virus present in respirable aerosols exhaled from infected hosts. Here, we used the ferret model to evaluate aerosol shedding patterns and measure the amount of infectious virus present in exhaled respirable aerosols. By comparing these parameters among a panel of human and avian influenza viruses exhibiting diverse respiratory droplet transmission efficiencies, we are able to report that ferrets infected by highly transmissible influenza viruses exhale a greater number of aerosol particles and more infectious virus within respirable aerosols than ferrets infected by influenza viruses that do not readily transmit. Our findings improve our understanding of the ferret transmission model and provide support for the potential for influenza virus aerosol transmission. 相似文献
5.
Luciane P Gaspar Ana C B Silva Andre M O Gomes M?nica S Freitas Ana P D Ano Bom Waleska D Schwarcz Jiri Mestecky Miroslav J Novak Débora Foguel Jerson L Silva 《The Journal of biological chemistry》2002,277(10):8433-8439
Enveloped animal viruses must undergo membrane fusion to deliver their genome into the host cell. We demonstrate that high pressure inactivates two membrane-enveloped viruses, influenza and Sindbis, by trapping the particles in a fusion-intermediate state. The pressure-induced conformational changes in Sindbis and influenza viruses were followed using intrinsic and extrinsic fluorescence spectroscopy, circular dichroism, and fusion, plaque, and hemagglutination assays. Influenza virus subjected to pressure exposes hydrophobic domains as determined by tryptophan fluorescence and by the binding of bis-8-anilino-1-naphthalenesulfonate, a well established marker of the fusogenic state in influenza virus. Pressure also produced an increase in the fusion activity at neutral pH as monitored by fluorescence resonance energy transfer using lipid vesicles labeled with fluorescence probes. Sindbis virus also underwent conformational changes induced by pressure similar to those in influenza virus, and the increase in fusion activity was followed by pyrene excimer fluorescence of the metabolically labeled virus particles. Overall we show that pressure elicits subtle changes in the whole structure of the enveloped viruses triggering a conformational change that is similar to the change triggered by low pH. Our data strengthen the hypothesis that the native conformation of fusion proteins is metastable, and a cycle of pressure leads to a final state, the fusion-active state, of smaller volume. 相似文献
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Annexin II incorporated into influenza virus particles supports virus replication by converting plasminogen into plasmin 总被引:1,自引:0,他引:1
LeBouder F Morello E Rimmelzwaan GF Bosse F Péchoux C Delmas B Riteau B 《Journal of virology》2008,82(14):6820-6828
For influenza viruses to become infectious, the proteolytic cleavage of hemagglutinin (HA) is essential. This usually is mediated by trypsin-like proteases in the respiratory tract. The binding of plasminogen to influenza virus A/WSN/33 leads to the cleavage of HA, a feature determining its pathogenicity and neurotropism in mice. Here, we demonstrate that plasminogen also promotes the replication of other influenza virus strains. The inhibition of the conversion of plasminogen into plasmin blocked influenza virus replication. Evidence is provided that the activation of plasminogen is mediated by the host cellular protein annexin II, which is incorporated into the virus particles. Indeed, the inhibition of plasminogen binding to annexin II by using a competitive inhibitor inhibits plasminogen activation into plasmin. Collectively, these results indicate that the annexin II-mediated activation of plasminogen supports the replication of influenza viruses, which may contribute to their pathogenicity. 相似文献
8.
The influenza A virus M2 cytoplasmic tail is required for infectious virus production and efficient genome packaging
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The M2 integral membrane protein encoded by influenza A virus possesses an ion channel activity that is required for efficient virus entry into host cells. The role of the M2 protein cytoplasmic tail in virus replication was examined by generating influenza A viruses encoding M2 proteins with truncated C termini. Deletion of 28 amino acids (M2Stop70) resulted in a virus that produced fourfold-fewer particles but >1,000-fold-fewer infectious particles than wild-type virus. Expression of the full-length M2 protein in trans restored the replication of the M2 truncated virus. Although the M2Stop70 virus particles were similar to wild-type virus in morphology, the M2Stop70 virions contained reduced amounts of viral nucleoprotein and genomic RNA, indicating a defect in vRNP packaging. The data presented indicate the M2 cytoplasmic tail plays a role in infectious virus production by coordinating the efficient packaging of genome segments into influenza virus particles. 相似文献
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Roethl E Gassner M Krenn BM Romanovskaya-Romanko EA Seper H Romanova J Nakowitsch S Sturlan S Wolschek M Sirotkin A Kiselev O Muster T Egorov A 《Journal of virology》2011,85(21):11139-11145
In general, antibiotics are not rated as substances that inhibit or support influenza virus replication. We describe here the enhancing effect of the polyene antibiotic amphotericin B (AmB) on influenza virus growth in Vero cells. We show that isolation rates of influenza A and B viruses from clinical samples can be dramatically enhanced by adding AmB to the culture medium. We demonstrate that AmB promotes the viral uptake and endocytic processing of the virus particles. This effect is specific for Vero and human nasal epithelial cells and was not observed in Madin-Darby canine kidney cells. The effect of AmB was subtype specific and more prominent for human seasonal influenza strains but absent for H5N1 human viruses. The AmB-enhancing effect seemed to be solely due to the viral hemagglutinin function. Our results indicate that the use of AmB may facilitate influenza virus isolation and production in Vero cells. 相似文献
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Fabian P McDevitt JJ DeHaan WH Fung RO Cowling BJ Chan KH Leung GM Milton DK 《PloS one》2008,3(7):e2691
Background
Recent studies suggest that humans exhale fine particles during tidal breathing but little is known of their composition, particularly during infection.Methodology/Principal Findings
We conducted a study of influenza infected patients to characterize influenza virus and particle concentrations in their exhaled breath. Patients presenting with influenza-like-illness, confirmed influenza A or B virus by rapid test, and onset within 3 days were recruited at three clinics in Hong Kong, China. We collected exhaled breath from each subject onto Teflon filters and measured exhaled particle concentrations using an optical particle counter. Filters were analyzed for influenza A and B viruses by quantitative polymerase chain reaction (qPCR). Twelve out of thirteen rapid test positive patients provided exhaled breath filter samples (7 subjects infected with influenza B virus and 5 subjects infected with influenza A virus). We detected influenza virus RNA in the exhaled breath of 4 (33%) subjects–three (60%) of the five patients infected with influenza A virus and one (14%) of the seven infected with influenza B virus. Exhaled influenza virus RNA generation rates ranged from <3.2 to 20 influenza virus RNA particles per minute. Over 87% of particles exhaled were under 1 µm in diameter.Conclusions
These findings regarding influenza virus RNA suggest that influenza virus may be contained in fine particles generated during tidal breathing, and add to the body of literature suggesting that fine particle aerosols may play a role in influenza transmission. 相似文献13.
Defective interfering (DI) RNAs are highly deleted forms of the infectious genome that are made by most families of RNA viruses. DI RNAs retain replication and packaging signals, are synthesized preferentially over infectious genomes, and are packaged as DI virus particles which can be transmitted to susceptible cells. Their ability to interfere with the replication of infectious virus in cell culture and their potential as antivirals in the clinic have long been known. However, until now, no realistic formulation has been described. In this review, we consider the early evidence of antiviral activity by DI viruses and, using the example of DI influenza A virus, outline developments that have led to the production of a cloned DI RNA that is highly active in preclinical studies not only against different subtypes of influenza A virus but also against heterologous respiratory viruses. These data suggest the timeliness of reassessing the potential of DI viruses as a novel class of antivirals that may have general applicability. 相似文献
14.
A mutant cell line of porcine kidney cells that resists the cytopathic effect of influenza virus has been obtained and characterized. These cells, designated ESK-R, were originally obtained by prolonged cultivation of cells surviving influenza B/Kanagawa/73 virus infection. No infectious virus was recovered from ESK-R cells, and no evidence for the presence of virus antigens in the cells was demonstrated by immunofluorescent staining. ESK-R cells also showed a distinct resistance to various other strains of both types A and B influenza viruses. The growth of mumps, Sendai, or Newcastle disease virus was considerably restricted, but the cell line normally supported the replication of vesicular stomatitis virus. ESK-R cells were found to lack specific receptors for influenza virus as determined by fluorescence-activated cell sorter analyses. The membrane barrier of ESK-R cells was successfully overcome by nonspecific endocytosis of calcium-coprecipitated virus particles followed by production of an appreciable amount of progeny virus. 相似文献
15.
流感病毒基因的密码子偏好性及聚类分析 总被引:1,自引:0,他引:1
流行性感冒病毒是一种造成人类及动物患流行性感冒的RNA病毒,它造成急性上呼吸道感染,并由空气迅速传播,在世界各地常有周期性的大流行。根据该病毒的基因组CDS序列,探讨了基因组序列密码子的使用模式和特性,并进行了病毒间的聚类分析。结果表明:流感病毒的G+C含量均低于A+U含量,偏向使用以A、U结尾的密码子的程度比使用以G、C结尾的较高,CUG、UCA、AGU、AGC、AGA、AGG、GUG、CCA、ACA、GGA、GCA、AUU、UGA、CAU、CAA、AAU、AAA、GAA等18个密码子为流感病毒共有的偏好性密码子,且以A结尾的居多,尤其偏爱AGA、GGA。聚类结果表明首先亚洲流感病毒H2N2和香港流感病毒H2N2聚为一类,亚洲流感病毒H1N1和俄罗斯流感病毒H1N1聚为一类,1997年和2003年~2004年发生的人禽流感聚为一类,说明它们的密码子使用的偏好性相似;而2009年爆发的甲型H1N1流感和任何一个流感的距离都比较远,说明甲型H1N1流感病毒是一种新型的病毒,不同于以往任何一种流感病毒。 相似文献
16.
Visna virus particles inhibit influenza virus hemagglutination in an assay for neuraminic acid-containing viruses. Pretreatment of visna virus with neuraminidase abolished hemagglutination inhibition activity but did not significantly affect attachment, infectivity, or virus-induced cell fusion in sheep choroid plexus cell monolayers. 相似文献
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The infection of viruses to a neighboring cell is considered to be beneficial in terms of evasion from host anti-virus defense systems. There are two pathways for viral infection to "right next door": one is the virus transmission through cell-cell fusion by forming syncytium without production of progeny virions, and the other is mediated by virions without virus diffusion, generally designated cell-to-cell transmission. Influenza viruses are believed to be transmitted as cell-free virus from infected cells to uninfected cells. Here, we demonstrated that influenza virus can utilize cell-to-cell transmission pathway through apical membranes, by handover of virions on the surface of an infected cell to adjacent host cells. Live cell imaging techniques showed that a recombinant influenza virus, in which the neuraminidase gene was replaced with the green fluorescence protein gene, spreads from an infected cell to adjacent cells forming infected cell clusters. This type of virus spreading requires HA activation by protease treatment. The cell-to-cell transmission was also blocked by amantadine, which inhibits the acidification of endosomes required for uncoating of influenza virus particles in endosomes, indicating that functional hemagglutinin and endosome acidification by M2 ion channel were essential for the cell-to-cell influenza virus transmission. Furthermore, in the cell-to-cell transmission of influenza virus, progeny virions could remain associated with the surface of infected cell even after budding, for the progeny virions to be passed on to adjacent uninfected cells. The evidence that cell-to-cell transmission occurs in influenza virus lead to the caution that local infection proceeds even when treated with neuraminidase inhibitors. 相似文献
19.
Location of Ferritin-Labeled Concanavalin A Binding to Influenza Virus and Tumor Cell Surfaces 总被引:1,自引:0,他引:1
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Concanavalin A (Con-A) was linked to ferritin with glutaraldehyde and chromatographed on Sepharose 6B to separate unconjugated Con-A and ferritin from covalently cross-linked molecules. Ehrlich ascites tumor cells were infected with WSA influenza virus, stained at intervals with the ferritin-labeled Con-A and examined by electron microscopy. The surfaces of most mature viruses were specifically stained, providing direct evidence that influenza viruses maturing in this cell type have exposed Con-A receptor sites. The ferritin cores of the staining reagent were found at an average distance of 21.3 nm from the virus membrane and 10.8 nm from the uninfected cell membrane. This finding was interpreted to mean that the population of Con-A receptor sites on influenza virus particles is located at an average distance from the virus membrane twice that of the population of Con-A receptor sites found on uninfected cells. The structural elements of viral membranes can provide a reliable means for evaluating electron microscopy staining reagents, thereby enhancing their usefulness as probes for the study of membrane relationships. 相似文献
20.
Stefan J. Halbherr Terza Brostoff Merve Tippenhauer Samira Locher Marianne Berger Rentsch Gert Zimmer 《PloS one》2013,8(6)
Highly pathogenic avian influenza viruses (HPAIV) of subtype H5N1 not only cause a devastating disease in domestic chickens and turkeys but also pose a continuous threat to public health. In some countries, H5N1 viruses continue to circulate and evolve into new clades and subclades. The rapid evolution of these viruses represents a problem for virus diagnosis and control. In this work, recombinant vesicular stomatitis virus (VSV) vectors expressing HA of subtype H5 were generated. To comply with biosafety issues the G gene was deleted from the VSV genome. The resulting vaccine vector VSV*ΔG(HA) was propagated on helper cells providing the VSV G protein in trans. Vaccination of chickens with a single intramuscular dose of 2×108 infectious replicon particles without adjuvant conferred complete protection from lethal H5N1 infection. Subsequent application of the same vaccine strongly boosted the humoral immune response and completely prevented shedding of challenge virus and transmission to sentinel birds. The vaccine allowed serological differentiation of infected from vaccinated animals (DIVA) by employing a commercially available ELISA. Immunized chickens produced antibodies with neutralizing activity against multiple H5 viruses representing clades 1, 2.2, 2.5, and low-pathogenic avian influenza viruses (classical clade). Studies using chimeric H1/H5 hemagglutinins showed that the neutralizing activity was predominantly directed against the globular head domain. In summary, these results suggest that VSV replicon particles are safe and potent DIVA vaccines that may help to control avian influenza viruses in domestic poultry. 相似文献