| ability of temperature-sensitive mutants of the recombinant influenza s/n (h2n1) virus to induce immunity to parental (h0n1 and h2n2) viruses. | the behavior in mice of two thermosensitive (ts) mutants (denoted ts217 and ts700) of the recombinant influenza virus s/n (h2n1) was studied. the parental thermoresistant (tr) virus and both of the mutants were capable of inducing protection against pneumotropic a/singapore (h2n2) and a/ws (h0n1) challenge viruses. immunity against the singapore virus, with which the s/n virus shared the hemagglutinin, developed earlier than against the ws virus, with which the s/n virus shared the neuraminidase ... | 1976 | 965084 |
| influenza virus: association of mouse-lung virulence with plaque formation in mouse kidney cells. | in genetic recombination experiments with the mouse-lung-adapted human influenza a/engl/1/61 (h2n2) and an avian influenza strain a/rostock/34 (fpv) (hav1n1) which is avirulent for the mouse lung, recombinants in which hemagglutinin and neuraminidase were either segregated (hav1n2; h2n1) or not segregated (hav1n1) were selected. the recombinants were studied for mouse-lung virulence and their ability to propagate in mouse kidney cells, mouse embryo fibroblasts, chick embryo kidney cells and chic ... | 1976 | 1010711 |
| cell-mediated immune response to influenza virus infections in mice. | the local and systemic cell-mediated immune (cmi) responses to influenza virus infection in mice were examined by leukocyte migration inhibition and lymphocyte-mediated cytotoxicity tests. mice were inoculated intranasally with 5 50% lethal doses of the a/wsn (h0n1) strain of influenza virus. cells from the lymph nodes draining the upper and lower respiratory tract were used to measure the local response, and the spleen was the source of cells used for systemic determinations. the local response ... | 1976 | 1248876 |
| class i h-2d-restricted cytotoxic t lymphocytes recognize the neuraminidase glycoprotein of influenza virus subtype n1. | class i major histocompatibility complex-restricted cytotoxic t lymphocytes (ctl) that recognize the neuraminidase (na) glycoprotein of subtype n1 influenza a viruses have been demonstrated in balb/c mice. responses to na were obtained only in protocols that use two in vivo inoculations of virus, including a recombinant vaccinia virus containing the na of subtype n1 influenza virus (na-vac) to prime or boost. restimulation in vitro was also required for ctl recognition of na and strongly depende ... | 1990 | 2304137 |
| [suppressive action of the influenza virus on the bone marrow stem cells of mice]. | the effect of pathogenic and noninfectious influenza viruses with different surface antigens on colony-forming stem cells of (cba x c57bl/6)f1 mice was studied. bone marrow cells were infected with a/pr8/34 (h1n1)/a/krasnodar/101/59 (h2n2) viruses, a recombinant a/pk-6-3 (h2n1) strain thereof, a/khabarovsk/933/77 (h1n1) strain; then they were inoculated intravenously to irradiated (820 rad) syngeneic recipients, and colony-forming units (cfu) were determined in the spleens 9 days after injection ... | 1988 | 2904194 |
| morphological changes in bhk-21 cells infected with s-n (h2n1) influenza virus. | | 1973 | 4129678 |
| nonlinkage of neurovirulence exclusively to viral hemagglutinin or neuraminidase in genetic recombinants of a-nws (hon1) influenza virus. | genetic recombination of the neurovirulent a/nws/cc-p (h0n1) and the non-neurovirulent a/jap.305/57 (h2n2) influenza viruses in which hemagglutinin and neuraminidase were segregated (h0n2, h2n1) were studied for neurovirulence in mice immunosuppressed with cyclophosphamide (cpa) which permitted full expression of virulence. both h0n2 and h2n1 recombinants replicated in the brain (in contrast to the h2n2 parent) and both produced lethal effects in cpa-treated animals. therefore we conclude that a ... | 1973 | 4688703 |
| roles of influenza virus infectivity and glycosylation of viral antigen for recognition of target cells by cytolytic t lymphocytes. | the influenza virus strains a/jap (h2n2) and the recombinant strain a/jap/bel (h2n1) were tested before and after uv-light inactivation for their ability to sensitize target cells for cytotoxic t-cell lysis (ctl). infectious preparations were efficient sensitizers for both specific and cross-reactive ctl, exposure of the cells to even low doses of virus resulting in almost maximum susceptibility. when inactivated, however, a/jap/bel was about 10 times more efficient than a/jap at sensitizing the ... | 1981 | 6971249 |
| cross-protection of mice immunized with different influenza a (h2) strains and challenged with viruses of the same ha subtype. | cross-protection of mice immunized with inactivated preparations of human and avian influenza a (h2) viruses was determined after lethal infection with mouse-adapted (ma) variants of human a/jap x bell/57 (h2n1) and avian a/njers/78 (h2n3) viruses. the ma variants differed from the original strains by acquired virulence for mice and changes in the ha antigenicity. these studies indicated that mice vaccinated with human influenza a (h2) viruses were satisfactorily protected against challenge with ... | 1997 | 9607078 |
| the feasibility of using high resolution genome sequencing of influenza a viruses to detect mixed infections and quasispecies. | the rapidly expanding availability of de novo sequencing technologies can greatly facilitate efforts to monitor the relatively high mutation rates of influenza a viruses and the detection of quasispecies. both the mutation rates and the lineages of influenza a viruses are likely to play an important role in the natural history of these viruses and the emergence of phenotypically and antigenically distinct strains. | 2009 | 19771155 |
| a human cd4+ t cell epitope in the influenza hemagglutinin is cross-reactive to influenza a virus subtypes and to influenza b virus. | the hemagglutinin protein (ha) of the influenza virus family is a major antigen for protective immunity. thus, it is a relevant target for developing vaccines. here, we describe a human cd4(+) t cell epitope in the influenza virus ha that lies in the fusion peptide of the ha. this epitope is well conserved in all 16 subtypes of the ha protein of influenza a virus and the ha protein of influenza b virus. by stimulating peripheral blood mononuclear cells (pbmcs) from a healthy adult donor with pep ... | 2012 | 22718815 |
| isolation of mixed subtypes of influenza a virus from a bald eagle (haliaeetus leucocephalus). | from april 2007 to march 2008, cloacal swabs were obtained from 246 casualty raptors recovered by various wildlife rehabilitation centers in the united states. the swabs were placed in a virus transport medium and transported to the laboratory on ice packs. at the laboratory, the samples were pooled with each pool consisting of five samples. all pools (n = 50) were screened for the presence of avian influenza virus (aiv) using a real time reverse transcription-polymerase chain reaction (rrt-pcr) ... | 2010 | 20667110 |
| ubiquitous reassortments in influenza a viruses. | the influenza a virus is a negative-stranded rna virus composed of eight segmented rna molecules, including polymerases (pb2, pb1, pa), hemagglutinin (ha), nucleoprotein (np), neuraminidase (na), matrix protein (mp), and nonstructure gene (ns). the influenza a viruses are notorious for rapid mutations, frequent reassortments, and possible recombinations. among these evolutionary events, reassortments refer to exchanges of discrete rna segments between co-infected influenza viruses, and they have ... | 2008 | 18942162 |
| postreassortment changes in a model system: ha-na adjustment in an h3n2 avian-human reassortant influenza virus. | in our previous studies we described the postreassortment changes in the hemagglutinin (ha) of h2n1, h3n1, h4n1 and h13n1 influenza a virus reassortants with has derived from avian viruses and low-functional neuraminidase (na) of a human parent virus a/ussr/90/77 (h1n1). the changes involved amino acid substitutions that increased the negative local charge in the vicinity of the receptor-binding pocket and decreased the affinity of ha to sialic acid receptors. in the present report we describe t ... | 2005 | 15789269 |
| intergenic ha-na interactions in influenza a virus: postreassortment substitutions of charged amino acid in the hemagglutinin of different subtypes. | in our previous studies influenza a virus reassortants having neuraminidase (na) gene of a/ussr/90/77 (h1n1) strain and hemagglutinin (ha) genes of h3, h4 and h13 subtypes were shown to produce a low virus yield and to exhibit a strong tendency to virion aggregation. more detailed studies with the use of a h3n1 reassortant and its high-yield non-aggregating variants revealed that na of a/ussr/90/77 strain is inefficient in the removal of the terminal sialic acid residues from the virion componen ... | 2000 | 10725545 |
| [gene analysis and phenotypic characteristic of highly-reproductive reassortants, containing the gene for bird influenza virus subtype h2 hemagglutinin]. | a series of reassortant clones with antigenic formulae h2n1 and h2n3 were produced by genetic reassortment performed with the use of an avian influenza virus, a/pintail duck/primorie/695/76 (h2n3) and a high-yield reassortant strain x-67. preliminary identification of the parent origin of np and ns genes for 5 reassortants was performed by comparison of the mobilities of virus-specific proteins in polyacrylamide gel electrophoresis. the parent origin of genes of internal and nonstructural protei ... | 2000 | 10695039 |
| recombination of human influenza a viruses in nature. | in 1977, a unique event occurred in the epidemiology of influenza when a virus of the influenza a (h1n1) subtype, similar to a virus that had occurred in 1950, reappeared and caused worldwide epidemics but did not replace the prevailing influenza a (h2n2) subtype. consequently, the two viruses co-circulated throughout the world and mixed infection of some individuals with both virus strains was detected, raising the possiblitity that recombination between the two strains might affect the future ... | 1980 | 7366737 |
| fine specificity of the in vitro antibody response to influenza virus by human blood lymphocytes. | the fine specificity of anti-influenza antibody produced in vitro by human pbm stimulated with different strains of influenza virus was examined by competition binding in solid phase enzyme immunoassay. most of the antibody produced in vitro is directed to strain-specific or cross-reactive determinants on the hemagglutinin molecule. the extent of cross-reactivity is dependent on the strain of virus used to stimulate pbm as well as the individual tested and presumably on his previous exposure to ... | 1983 | 6350452 |
| in vitro antibody response to influenza virus. ii. specificity of helper t cell recognizing hemagglutinin. | intraperitoneal immunization of mice with liver influenza virus was shown to induce helper t (th) cells with specificity for the hemagglutinin (ha). the interaction of virus-primed th cells with purified ha was studied independently of b cell reactivity to the same antigen by using the generation of nonspecific help as an index of activation of ha-specific th cells. th cells from mice primed with any of the h3 viruses a/aichi/68 x a/bel/42 (h3n1), a/memphis/102/72 x a/bel/42 (h3n1) or a/port cha ... | 1981 | 6166681 |
| studies on the structure of the haemagglutinin. | the biosynthesis of the haemagglutinin glycoproteins of infectious influenza virus particles involves proteolytic cleavage of the primary translation products and the amino acid sequences at the two sites of processing are presented. in addition, details of the primary structure of the haemagglutinin of a/japan/305/57 (h2n1) are reported and compared with information available for haemagglutinins of other subtypes. | 1980 | 6103550 |