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  • strains
  • Changes in the HA of circulating viruses (antigenic drift) require periodic replacement of the vaccine strains during interpandemic periods. (cdc.gov)
  • Furthermore, this characteristic mutation is not conserved among avian influenza viruses but is prevalent among mouse-adapted strains, indicating a host-dependent mutation. (asm.org)
  • Taken together, our results indicate that strong intrinsic barriers to reassortment between seasonal H3N2 and pH1N1 viruses are few but that the reassortants formed are attenuated relative to parental strains. (asm.org)
  • However, influenza viruses evolve under drug selection pressure to generate strains resistant to these drugs. (asm.org)
  • Certain highly virulent influenza strains cause more serious disease and kill more people, while some of the damage is caused by the stronger immune response elicited by such strains, especially in the lung. (medindia.net)
  • The observed response resembled the so-called "cytokine storm" situation that is thought to cause the lung tissue damage associated with virulent influenza strains. (medindia.net)
  • This renders antibody responses ineffective in providing protection against antigenically drifted strains that emerge frequently to cause seasonal influenza outbreaks. (asm.org)
  • However, it relies on highly specialized selection methods to isolate the transfectant viruses from the helper virus, which restricts its use to certain RNA segments of a limited number of viral strains. (asm.org)
  • avian influenza vir
  • To investigate the molecular changes that occur during adaptation of a low-pathogenic avian influenza virus subtype commonly isolated from migratory birds to a mammalian host, we serially passaged the avirulent wild-bird H5N2 strain A/Aquatic bird/Korea/W81/05 (W81) in the lungs of mice. (asm.org)
  • Development and application of a triplex real-time PCR assay for the simultaneous detection of avian influenza virus subtype H5, H7 and H9. (amedeo.com)
  • vitro
  • Although encouraging results have been demonstrated in vitro and in animal models, most oncolytic viruses have failed to impress in the clinical setting. (mdpi.com)
  • Genes
  • PB2∆ induces the expression of IFNβ and IFN-stimulated genes by direct interaction with the cellular adapter protein MAVS, thereby reducing viral replication of IFN-sensitive viruses such as IAV or vesicular stomatitis virus. (sigmaaldrich.com)
  • Although there is broad experimental support for the DRiP hypothesis, careful kinetic analysis of the generation of defined peptide class I complexes has been limited to studies of recombinant vaccinia viruses expressing genes derived from other organisms. (jimmunol.org)
  • Reassortment complements spontaneous mutation in influenza A virus NP and M1 genes to accelerate adaptation to a new host. (nih.gov)
  • mice
  • To our knowledge, this is the first study that the isoleucine residue at position 97 in PA plays a key role in enhanced virulence in mice and is implicated in the adaptation of avian influenza viruses to mammalian hosts. (asm.org)
  • To acquire virulence in mice, influenza A viruses usually must adapt to these hosts over several consecutive generations (serial passages) in the lungs or brain ( 1 , 25 , 30 ). (asm.org)
  • A recombinant influenza A virus expressing an RNA-binding-defective NS1 protein induces high levels of beta interferon and is attenuated in mice. (microbiologyresearch.org)
  • When the researchers used a weaker virus, the Socs4 mutants survived but again showed more severe symptoms than mice with intact SOCS4. (medindia.net)
  • When the researchers analyzed the immune response in the Socs4 mutants they found that the mutant mice responded to influenza virus with production of abnormally high levels of cytokines and chemokines--both small molecules that promote inflammation. (medindia.net)
  • In addition to the aberrant cytokine production, the mutant mice also appeared defective in mobilization of virus-specific killer T cells to the lungs. (medindia.net)
  • Adoptive transfer of memory T cells from immunized mice, but not of memory B cells, protected naïve recipients against lethal heterosubtypic influenza virus challenge. (asm.org)
  • The mechanism for this cross-protection has been studied extensively in mice immunized with live, replicating influenza virus and has been attributed to cross-reactive cytotoxic T (Tc) cells ( 11 , 26 , 37 , 44 , 45 , 56 , 57 ). (asm.org)
  • showed that immunization with sublethal doses of live viruses protected Ig −/− , CD1 −/− , and γδ −/− mice from lethal heterosubtypic challenges ( 8 ). (asm.org)
  • virions
  • The influenza A virus (IAV) genome is divided into eight distinct RNA segments believed to be copackaged into virions with nearly perfect efficiency. (pnas.org)
  • Influenza virus is an unusual pathogen in that it is pleomorphic, capable of forming virions ranging in shape from spherical to filamentous. (springer.com)
  • In the latter model, we also demonstrated the inability of the virus to carry out multiple replication cycles, irrespective of the presence of cleaved HA subunits in the released virions. (deepdyve.com)
  • Most influenza A virions fail to express at least one essential viral protein. (nih.gov)
  • subtype
  • Due to functional constraints, some epitopes, like the immunodominant HLA-A*0201-restricted matrix protein 1 (M1 58-66 ) epitope, are highly conserved between influenza A viruses regardless of their subtype or host species of origin. (asm.org)
  • live influenza virus
  • Therefore, it appears that heterosubtypic immunity induced by live influenza virus is a multifaceted phenomenon that involves not only the Tc-cell response but also other responses. (asm.org)
  • replicate
  • It has been known for many years that viruses have the ability to replicate in and lyse cancer cells. (mdpi.com)
  • The viruses replicate efficiently in their natural hosts but replicate poorly if at all in other species ( 53 ). (asm.org)
  • Taken together, these findings show that kinases produced by host cells can control the ability of viruses to replicate by modifying the viral nucleoproteins. (elifesciences.org)
  • populations
  • We found that each drug increased the frequency of mutations in influenza virus populations and decreased the virus' specific infectivity, indicating a mutagenic mode of action. (asm.org)
  • We were able to drive viral populations to extinction by passaging influenza virus in the presence of each drug, indicating that complete lethal mutagenesis of influenza virus populations can be achieved when a sufficient mutational burden is applied. (asm.org)
  • Population-wide resistance to these mutagenic agents did not arise after serial passage of influenza virus populations in sublethal concentrations of drug. (asm.org)
  • Typically the fitness of antigenically variant viruses is not the same as wild type, and therefore such viruses are not likely to spread in well immunized populations. (virology.ws)
  • Defining the specific factors that govern the evolution and transmission of influenza A virus (IAV) populations is of critical importance for designing more-effective prediction and control strategies. (asm.org)
  • As a result, virus populations that contain more SIPs undergo more-frequent superinfection. (asm.org)
  • Noninfectious CKP are present in excess of PFP in virus populations with full-size NS1 and induce apoptosis that is temporally delayed and morphologically different than that initiated by infectious CKP present in the virus population expressing truncated NS1. (asm.org)
  • Clonogenic assays have been used to quantify the capacity of virus populations to kill cells. (asm.org)
  • Virus populations analyzed in this manner measure the capacity of a single virus particle to kill a single cell, thereby preventing its growth into a visible colony. (asm.org)
  • This report quantifies for the first time the CKP capacity of influenza virus populations. (asm.org)
  • molecular
  • The molecular basis of influenza virus host range restriction and adaptation to a new host species is poorly understood. (asm.org)
  • However, with the advent of culture-independent molecular diagnostic techniques it is now estimated that viruses are detected during half of all COPD exacerbations and are associated with poorer clinical outcomes. (ersjournals.com)
  • Our data suggest a selective role of the actin network in inducing a restriction to influenza virus replication, mostly depending on its molecular organization, the host cell type and virus replication phase. (deepdyve.com)
  • We also include a brief review of the clinical manifestations of influenza and the molecular determinants for virulence. (springer.com)
  • immune
  • AIDS vaccination has a pressing need for more potent vaccination vectors capable of eliciting strong, diversified, and long-lasting cellular immune responses against human immunodeficiency virus (HIV). (semanticscholar.org)
  • The explanation is multifactorial, determined by the complex interactions between the tumor and its microenvironment, the virus, and the host immune response. (mdpi.com)
  • Its attenuation is due to potent stimulation of the innate immune system by the virus. (semanticscholar.org)
  • The immune system and viruses have evolved and continue to evolve in response to each other. (nih.gov)
  • The mission of the Viral Immunology Section is focused on extending our basic understanding of the interaction between the immune system and viruses. (nih.gov)
  • Dr. Bennink obtained his Ph.D. from the University of Pennsylvania for the study of the specificity of virus immune effector T cells. (nih.gov)
  • The innate immune system senses influenza A virus (IAV) through different pathogen-recognition receptors including Toll-like receptor 7 (TLR7). (frontiersin.org)
  • A study published on May 8th in PLOS Pathogens identifies SOCS4 as a key regulator of the immune response against influenza virus. (medindia.net)
  • cytotoxic T-ce
  • This reduced inflammation was associated with enhanced early recruitment of T cells, both CD4 + and CD8 + , and with early influenza virus-specific cytotoxic T-cell responses. (asm.org)
  • Reassortment
  • Reassortment between viruses leading to appearance of avian virus HA and human virus NA on the virion surface often resulted in decreasing the replicative potential of the formed variants because of disturbance of a functional balance between "alien" HA and NA. (springer.com)
  • This type of reassortment, involving highly divergent viruses, brings about large shifts in genotype and phenotype, which can facilitate host species transfers ( 5 ). (asm.org)
  • Reassortment events have contributed to the emergence of every major influenza pandemic of the past century ( 7 ). (asm.org)
  • RNPs
  • The tail loop has been shown biochemically to be important for oligomerization of NP monomers within the RNP ( 10 - 12 ), but structural information on the native RNP has been lacking, and it is unclear how the NPs form the helical filament structures that are characteristic of influenza virus RNPs ( 5 ). (sciencemag.org)
  • To address the plethora of biological questions surrounding the influenza virus RNP, we used cryogenic electron microscopy (cryo-EM) to analyze the structure of recombinant RNPs. (sciencemag.org)
  • lethal mutagenesis
  • We investigated the effectiveness of lethal mutagenesis as a strategy against influenza virus using three nucleoside analogs, ribavirin, 5-azacytidine, and 5-fluorouracil. (asm.org)
  • Together, our data suggest that lethal mutagenesis may be a particularly effective therapeutic approach with a high genetic barrier to resistance for influenza virus. (asm.org)
  • We investigated the effectiveness of lethal mutagenesis against influenza virus using three different drugs. (asm.org)
  • Lethal mutagenesis has been applied to a number of RNA viruses, most commonly with nucleoside (e.g., ribavirin and 5-azacytidine) and base (e.g., 5-fluorouracil) analogs. (asm.org)
  • nucleic acid
  • Although all of the DI genomes studied to date are shorter than the standard viral genome and are deletion mutants, it is possible some DI genome may contain an altered nucleic acid sequence(s) rather than a deletion(s) and become defective as well as interfering. (springer.com)
  • Ada, G. L., Perry, B. T.: Infectivity and nucleic acid content of influenza virus. (springer.com)
  • Ada, G. L., Perry, B. T.: Influenza virus nucleic acid relationship between biological characteristics of the vims particle and properties of the nucleic acid. (springer.com)