| the analysis of the monoclonal immune response to influenza virus. iii. the relationship between stimulation of virus-primed precursor b cells by heterologous viruses and reactivity of secreted antibodies. | individual splenic precursor b cells from balb/c mice primed with influenza virus pr8[a/pr/8/34 (h0n1)] were stimulated in vitro in the splenic fragment culture system by homologous or various heterologous influenza viruses. the specificity of the stimulated precursor cells was determined by analysis of the antibodies secreted by the ensuing plasma cell clone in a radioimmunoassay (ria). viruses of the h2n2 and h3n2 subtypes were unable to stimulate hemagglutinin (ha)- or neuraminidase (na)-comm ... | 1978 | 305935 |
| reappearance of h1n1 influenza virus in man: evidence for the persistence of the virus in domestic chickens. | serological studies on domestic poultry originating from china and hong kong suggest that the h1n1 virus may have persisted in domestic chickens prior to its reappearance in man in 1977. experimental infection of young, local strains of poultry provided equivocal evidence that 4-day-old chickens could be infected; virus was not recovered from infected 1-month-old chickens. | 1979 | 314358 |
| antigenic drift in influenza a viruses. i. selection and characterization of antigenic variants of a/pr/8/34 (hon1) influenza virus with monoclonal antibodies. | antigenic variants of a/pr/8/34 [hon1] influenza virus were selected after a single passage of the parent virus in embryonated chicken eggs in the presence of monoclonal antibodies to this virus. the monoclonal antibodies were produced by a hybridoma and were specific for an antigenic determinant on the ha molecule of the parent virus. seven antigenic variants were analyzed with 95 monoclonal anti-ha antibodies prepared in vitro in the splenic fragment culture system. three subgroups of antigeni ... | 1978 | 359746 |
| on the antiviral activity of diffusomycin (oxazolomycin). | the effect of the beta-lactone antibiotic diffusomycin (oxazolomycin) was investigated against vaccinia (lister), herpes simplex type 1 (kupka), influenza a (wsn; h1n1), and coxsackie a9 viruses. diffusomycin reduced significantly the plaque formation of enveloped dna and rna viruses by more than 90% in the range of the maximally tolerated dose. as could be shown with vaccinia virus, the antiviral action was not caused by virucidal effect on virions or by interaction with virus adsorption and pe ... | 1992 | 1359768 |
| genetic relatedness of the nucleoprotein (np) of recent swine, turkey, and human influenza a virus (h1n1) isolates. | the sequences of nucleoprotein (np) genes of recent human and turkey isolates of influenza a viruses, which serologically could be correlated to contemporary swine viruses, were determined. these sequences were closely related to the nps of these swine viruses and they formed a separate branch on the phylogenetic tree. while the early swine virus from 1931 resembled the avian strains in consensus amino acids of the np and in its ability to rescue np ts mutants of fowl plague virus in chicken emb ... | 1992 | 1536092 |
| rapid diagnosis of influenza a. comparison with elisa immunocapture and culture. | the directigen flu-a is an enzyme immunoassay for detecting in 15 min the influenza a nucleoproteinic antigen directly from specimens after passive adsorption on a cellulose membrane. the test was assessed using 160 frozen (-20 degrees c) specimens collected during the 1988-1989 a/h1n1 influenza epidemic and the 1989-1990 a/h3n2 epidemic. compared to the elisa immunocapture test, the sensitivity of the commercial test was 87.8% and the specificity was 97.6%. when compared to isolation of viruses ... | 1992 | 1634600 |
| [features of mutated changes of genomic rna of cold-adapted and hr-variants of influenza group a virus, detected by rna:rna hybridization]. | the presence of mutations in the majority of the genes of cold-adapted strains a/leningrad/134/17/57 (h2n2), a/leningrad/134/47/57 (h2n2) and a/pr/8/59/1 (h1n1) of influenza a virus has been demonstrated by the rna-rna hybridization with the subsequent electrophoresis of double-stranded rna in 7.5% polyacrylamide gel. the strains were cultivated 17, 47 and 59 passages in the chicken embryos at 25 degrees c. in the genomes of variants passaged in chicken embryos at optimal temperature of incubati ... | 1990 | 1706066 |
| correlation of amino acid residues in the m1 and m2 proteins of influenza virus with high yielding properties. | the ability of influenza a viruses to replicate to high titer in the allantoic sac of the chicken embryo has been mapped to the matrix protein gene (rna 7). because influenza a/wsn/33 (h1n1) virus grows poorly in this host but contains a matrix protein gene with a sequence similar to sequences from viruses that grow well in eggs, we derived a single gene reassortant containing only the m gene from a/wsn/33 (h1n1) in a background of the other 7 rna segments from a/philippines/2/82 (h3n2) (a low y ... | 1991 | 1867007 |
| avian cells expressing the murine mx1 protein are resistant to influenza virus infection. | the cdna encoding the murine mx1 protein, a mediator of resistance to influenza virus, was inserted into a replication-competent avian retroviral vector in either the sense (referred to as mx+) or the antisense (referred to as mx-) orientation relative to the viral structural genes. both vectors produced virus retaining the mx insert (mx recombinant viruses referred to as mx+ and mx-) following transfection into chicken embryo fibroblasts (cef). mx protein of the appropriate size and nuclear loc ... | 1991 | 1989389 |
| single amino acid substitutions in the hemagglutinin can alter the host range and receptor binding properties of h1 strains of influenza a virus. | we have previously characterized an influenza a (h1n1) virus which has host-dependent growth and receptor binding properties and have shown that a mutation which removes an oligosaccharide from the tip of the hemagglutinin (ha) by changing asn-129 to asp permits this virus to grow to high titer in mdbk cells, (c. m. deom, a. j. caton, and i. t. schulze, proc. natl. acad. sci. usa 83:3771-3775, 1986). we have now isolated monoclonal antibodies specific for the mutant ha and have used escape mutan ... | 1991 | 2033664 |
| agglutination of human o erythrocytes by influenza a(h1n1) viruses freshly isolated from patients. | the hemagglutinin titers of 10 influenza a (h1n1) viruses were examined using the erythrocytes of several species. human o erythrocytes showed the highest agglutination titer to the viruses, whereas chicken erythrocytes showed a low titer. these findings were noted for at least 10 passages by serial dilutions of the viruses in madin-darby canine kidney (mdck) cells. all influenza a(h1n1) viruses, plaque-cloned directly from throat-washing specimens of patients, also agglutinated human o but not ... | 1991 | 2066386 |
| selection of influenza a virus adsorptive mutants by growth in the presence of a mixture of monoclonal antihemagglutinin antibodies. | the influenza virus hemagglutinin contains four major regions that are recognized by antibodies able to neutralize viral infectivity. to investigate the effect of an antibody response directed against each of these sites on viral evolution, influenza virus a/pr/8/34 (h1n1) was grown in allantois-on-shell cultures in the presence of a mixture of monoclonal antihemagglutinin antibodies. this selection mixture contained antibodies (two or three antibodies per antigenic site) whose concentrations we ... | 1986 | 2418215 |
| evolutionary pathways of the pa genes of influenza a viruses. | nucleotide sequences of the pa genes of influenza a viruses, isolated from a variety of host species, were analyzed to determine the evolutionary pathways of these genes and the host specificity of the genes. results of maximum parsimony analysis of the nucleotide sequences indicate at least five lineages for the pa genes. those from human strains represent a single lineage, whereas the avian genes appear to have evolved as two lineages--one comprising genes from many kinds of birds (e.g., chick ... | 1989 | 2800339 |
| allantoic fluid protease activity during influenza virus infection. | neutral protease activity of allantoic fluid from embryonated chicken eggs was quantified during the course of influenza virus infection. antigenic subtypes of influenza a viruses selected for study were h1n1 strains pr/8/34, brazil/8/78, fm/1/47, the h3n2 strain bangkok/1/80 and the h5n9 turkey/ /ontario/66 as well as the sendai strain of parainfluenza type 1 virus. three different types of profiles of allantoic fluid proteases could be readily distinguished after infection of eggs with various ... | 1986 | 2873727 |
| nucleotide sequence of rna segment 7 and the predicted amino sequence of m1 and m2 proteins of fpv/weybridge (h7n7) and wsn (h1n1) influenza viruses. | since the gene products (m1 and m2) of influenza virus rna segment 7 have been implicated in host range restriction, sensitivity to the drug amantadine, virus yield in chicken embryos as well as in virus assembly and morphology, we have determined the nucleotide sequence of this rna segment for an avian [a/fpv/weybridge (h7n7)] and a human [a/wsn/33 (h1n1)] virus and compared it to that of the other influenza a virus strains. the results show that all ten strains of influenza a virus contain an ... | 1988 | 3414185 |
| subtype-specific identification of influenza virus in cell cultures with fitc labelled egg yolk antibodies. | we report on results obtained with a direct immunofluorescence test for subtype-specific identification of influenza virus in detached cells of mdck cultures after inoculation of 281 clinical specimens from patients with influenza-like disease. influenza virus antibodies were produced in eggs from immunized hens and labelled with fitc. in 157 cases cpe was found in mdck cells. a total of 57 cases of influenza a (h3n2), 86 cases of influenza a (h1n1), and 14 cases of influenza b were identified. ... | 1987 | 3547056 |
| the hemagglutinins of the human influenza viruses a and b recognize different receptor microdomains. | a cryptically i-active sialylglycoprotein (glycoprotein 2) isolated from bovine erythrocyte membranes as sendai virus receptor (suzuki, y., suzuki, t. and matsumoto, m. (1983) j. biochem. 93, 1621-1633) contains n-glycolylneuraminic acid (neugc) as its predominate sialic acid and exhibits poor receptor activity for a variety of influenza viruses. enzymatic modification of asialoglycoprotein-2 to contain n-acetylneuraminic acid (neuac) in the neuac alpha 2-3gal and neuac alpha 2-6gal sequences us ... | 1987 | 3663654 |
| [synthesis, cloning and determination of the primary structure of a full-size dna copy of the neuraminidase gene from influenza virus type a subtype h1n1]. | complete nucleotide sequence of the cloned full-length dna copy of the influenza virus a (h1n1) neuraminidase gene has been determined. the predicted amino acid sequence is compared with sequences of neuraminidases from other influenza virus strains. a section of the neuraminidase is found to be homologous to the chicken lysozyme catalytic centre. | 1985 | 4038348 |
| 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 |
| monoclonal antibodies to the hemagglutinin sa antigenic site of a/pr/8/34 influenza virus distinguish biologic mutants of swine influenza virus. | the dimorphic l and h hemagglutinin mutants of a/nj/11/76(h1n1) (swine) influenza virus differ pleiotropically in their replication and virulence characteristics and in their antigenicity. l mutants replicate less well in chicken embryos and madin-darby canine kidney cells and are more infective for swine than are h mutants. l and h mutants are not antigenically distinguishable in cross-neutralization tests with homotypic antisera, but they can be identified with certain heterotypic heterogeneou ... | 1983 | 6194531 |
| the role of wild birds in the spread of influenza viruses. | eggs deposited by different migrating wild bird species in pond farm areas in hungary were examined for yolk antibodies to different variants of human a/h3n2 influenza virus. antibodies to victoria/75 and texas/77 occurred in 17.9 and 32.0% of gull eggs, and 5.6 and 16.4% of common tern eggs, respectively, while antibodies to a/h1n1/77 occurred in roughly similar proportions (10.2 and 13.4%) in the eggs of both species. infection of the gull and tern populations of given areas by human and avian ... | 1980 | 6258400 |
| zoonotic studies on influenza in pigs and birds, india, 1980-81. | five hundred and twenty pig sera collected from pune, maharashtra state, india during 1980 were examined in haemagglutination inhibition (hi) tests to determine the antibody prevalence to nine human influenza virus strains covering the subtypes a(hon1), a(h1n1), a(h2n2), a(h3n2), type b and one swine influenza virus strain a(hsw1n1). this study indicated considerable prevalence of antibodies to the four h3n2 strains isolated from 1973 onwards, particularly to the two recent h3n2 strains, limited ... | 1983 | 6315619 |
| persistent infection with influenza a virus: evolution of virus mutants. | a persistent infection (persistent infection i) of baby hamster kidney (bhk) cells with the wsn (h1n1) strain of influenza a virus was established using a virus stock which contained a high proportion of defective-interfering (di) particles. virus recovered from passage 92 (388 days) of persistent infection i was used to establish a second persistent infection (persistent infection ii) in bhk cells. a number of phenotypic changes were identified in the virus isolated during the first 50 passages ... | 1984 | 6388147 |
| recombinant cold-adapted attenuated influenza a vaccines for use in children: molecular genetic analysis of the cold-adapted donor and recombinants. | a previously described cold-adapted attenuated virus, a/leningrad/134/17/57 (h2n2), was further modified by 30 additional passages in chicken embryos at 25 degrees c. this virus had a distinct temperature-sensitive (ts) phenotype, grew well in chicken embryos at 25 degrees c, and failed to recombine with reference ts mutants of fowl plague virus containing ts lesions in five genes coding for non-glycosylated proteins (genes 1, 2, 5, 7, and 8). recombination of a/leningrad/134/47/57 with wild-typ ... | 1984 | 6724694 |
| recombinant cold-adapted attenuated influenza a vaccines for use in children: reactogenicity and antigenic activity of cold-adapted recombinants and analysis of isolates from the vaccinees. | reactogenicity and antigenic activity of recombinants obtained by crossing cold-adapted donor of attenuation a/leningrad/134/47/57 with wild-type influenza virus strains a/leningrad/322/79(h1n1) and a/bangkok/1/79(h3n2) were studied. the recombinants were areactogenic when administered as an intranasal spray to children aged 3 to 15, including those who lacked or had only low titers of pre-existing anti-hemagglutinin and anti-neuraminidase antibody in their blood. after two administrations of va ... | 1984 | 6724695 |
| reversed single-radial-immunodiffusion test: the method for the assay of the antibody to influenza a nucleoprotein. | the reversed single-radial-immunodiffusion (r-srd) test using the avian-origin influenza a virus, a/chicken/germany "n'/49 (hav2neql) disrupted with 1.0% sarkosyl, was established as the quantitative method for the assay of a type-specific antibody, particularly of an anti-nucleoprotein antibody, in human sera. under the test conditions, human sera produced a definite opalescent zone around the well and the annulus area was found to have a high correlation to the antibody level of type a influen ... | 1981 | 6797098 |
| study of several genetic markers of two recombinants derived from autochthonous influenza virus type a strains. | two recombinants derived from autochthonous influenza virus type a strains were studied as regards neuraminidase activity, the rate of elution from chicken rbc and the sensitivity to nonspecific horse serum inhibitors. neuraminidase activity was lower in the a(h1n1) recombinant and in its collection and wild-type parents belonging to the same subtype than in the a(h3n2) recombinant and parental strains; the elution rate was much higher in the former than in the latter. in contrast to the parenta ... | 1982 | 6959412 |
| peptide mapping of 125i-labelled membrane protein of influenza viruses by reverse-phase high-performance liquid chromatography. | the resolution potential of reverse-phase high-performance liquid chromatography (hplc) for peptide analysis of hydrophobic viral membranes has been investigated, using as model the membrane (m) protein of influenza virus. proteolytic digests of 125i-labelled m protein and cnbr fragments, extracted from radioiodinated whole virus, have been separated on a ubondapak c18 column with an isopropanol or acetonitrile solvent system. peptide mapping of trypsin digests of m protein from a/pr/8/34 (h1n1) ... | 1982 | 7076781 |
| defective interfering influenza viruses and host cells: establishment and maintenance of persistent influenza virus infection in mdbk and hela cells. | wsn (h0n1) influenza virus upon undiluted passages in different species of cells, namely, bovine kidney (mdbk), chicken embryo (cef), and hela cells, produced a varying amount of defective interfering (di) virus which correlated well with the ability of the species of cell to produce infectious virus. however, the nature of the influenza di viral rna produced from a single clonal stock was essentially identical in all three cells types, suggesting that these cells do not exert a great selective ... | 1980 | 7463559 |
| selection of a single amino acid substitution in the hemagglutinin molecule by chicken eggs can render influenza a virus (h3) candidate vaccine ineffective. | this study investigated whether a single amino acid change in the hemagglutinin (ha) molecule influenced the efficacy of formalin-inactivated influenza a (h3n1) vaccine candidates derived from high-growth reassortants between the standard donor of high-yield genes (a/pr/8/34 [h1n1]) and host cell variants generated from the same clinical isolate (a/memphis/7/90 [h3n2]) by passage in embryonated chicken eggs. two clones of the isolate generated by growth in eggs differed from the parent virus (re ... | 1995 | 7609057 |
| the immunogenicity of reassortants of the cold-adapted influenza a master strain a/ann arbor/6/60 is determined by both the genes for cold-adaptation and the haemagglutinin gene. | two surface antigen segregants were prepared by co-infection of chicken embryo kidney cell cultures with reassortants of the cold-adapted influenza a master strain a/ann arbor/6/60-ca (h2n2) possessing the surface antigens of a/queensland/6/72 (h3n2) and a/hong kong/123/77 (h1n1) and other genes that were common to the master strain. the segregants were shown by serological tests to possess h3n1 and h1n2 surface antigens but it was not possible to determine the presence of h1 or n1 genes by sing ... | 1995 | 7646346 |
| host-specific hemagglutination of influenza a (h1n1) virus. | h1n1 strains of influenza a virus isolated during the influenza season of 1991-92 were divided into two groups according to the property of host-specific hemagglutination. group 1 viruses agglutinated human and chicken red blood cells. group 2 viruses agglutinated human but not chicken red blood cells. the viruses of both groups, however, showed the same antigenic structure determined with ferret antisera. the virus clones which were plaque-purified twice from a group 2 virus retained the charac ... | 1993 | 8246828 |
| the haemagglutinins of influenza a (h1n1) viruses in the 'o' or 'd' phases exhibit biological and antigenic differences. | influenza a (h1n1) viruses when initially isolated in mammalian cell cultures (mdck cells) had different agglutination reactions with chicken and guinea-pig erythrocytes compared to the same viruses after passage. on first isolation the virus ha resembled the 'o' phase viruses described originally by burnet and bull and agglutinated mammalian but not avian erythrocytes. after passage, the virus ha resembled a classical 'd' phase virus and agglutinated both avian and mammalian erythrocytes. monoc ... | 1993 | 8348927 |
| a h1 hemagglutinin of a human influenza a virus with a carbohydrate-modulated receptor binding site and an unusual cleavage site. | two receptor binding variants of the influenza virus a/tübingen/12/85 (h1n1) were separated by their different plaque formation in mdck cells. hemagglutination of variant i was restricted to red blood cells of guinea pigs, whereas variant ii also hemagglutinated chicken cells. the variants differed also in their ability to bind to alpha 2,6-linked sialic acid. evidence is presented that this difference is determined by a complex carbohydrate side chain at asparagine131 near the receptor binding ... | 1993 | 8460527 |
| influenza surveillance in pune, india, 1978-90. | continuous surveillance of influenza was carried out in pune between 1978 and 1990. most of the cases were identified during investigation of 16 outbreaks of influenza in pune over this period. the majority of cases were children. ten of the outbreaks occurred during rainy seasons. a total of 290 isolates consisting of several antigenic variants of influenza type a (h3n2), type a (h1n1), and type b viruses were isolated from throat/nasal swabs that were processed in chick embryos and mdck cell c ... | 1993 | 8490980 |
| [the use of the immunoperoxidase test with monoclonal antibodies for detecting influenza a viruses]. | the immunoperoxidase test was used to detect influenza virus in cells of a chorionallanthois shell of infected chicken embryos. application of monoclonal antibodies d8 and a11 in the analysis has permitted detecting reproduction of type a (subtypes h1n1, h2n2, h3n2) viruses, the pga titre of the respective allantois liquids being not lower than 1:16. the matrix protein and hemagglutinin, detection of which underlies this analysis, were found on the cell membrane, in the perinucleus region and as ... | 1995 | 8548071 |
| phenotypic expression of ha-na combinations in human-avian influenza a virus reassortants. | human-avian and human-mammalian influenza a virus reassortant clones with the neuraminidase (na) gene of the a/ussr/90/77 (h1n1) strain and hemagglutinin (ha) genes of h3, h4 and h13 subtypes had been shown in an earlier publication to produce low ha yields in the embryonated chicken eggs. the low ha titers had been shown to be due, at least in part, to the formation of virion clusters at 4 degrees c; the clustering was removed by the treatment with bacterial neuraminidase [rudneva et al., arch. ... | 1996 | 8712926 |
| distribution of antibodies to influenza a virus in chickens in japan. | a serological surveillance was carried out to detect antibody against influenza a virus in chicken sera. a total of 8,850 field samples were collected from 47 prefectures in japan. initially, all the sera were screened by agar gel immunodiffusion and those sera showing positive reaction were investigated for haemagglutination-inhibition (hi) and neuraminidase-inhibition antibodies against influenza viruses. only 6 samples had antibodies; 4 sera had antibodies against human subtype h1n1 virus; wi ... | 1995 | 8720048 |
| studies on the molecular basis for loss of the ability of recent influenza a (h1n1) virus strains to agglutinate chicken erythrocytes. | recent strains of influenza a but not b viruses have lost the ability to agglutinate chicken red blood cells (crbc). the h1n1 viruses isolated in japan during the 1991/92 season could be divided into two groups. group 1 viruses (a/aichi/4/92 and a/aichi/7/92) agglutinated goose red blood cells (grbc) and crbc, while group 2 viruses (a/aichi/24/92 and a/aichi/26/92) did not agglutinate crbc. there were no amino acid differences between them in the haemagglutinin (ha) polypeptide. reassortment exp ... | 1996 | 8887483 |
| a study of influenza a virus in the city of calcutta, india, high lighting the strain prevalence. | a decade wide (from 1981 to the end of 1993) study on incidences of influenza was carried out in the city of calcutta, india, by virus isolation and strain identification. over 3500 patients with acute respiratory infections were examined and 1950 throat swab specimens were inoculated in embryonated chicken eggs. only 339 haemagglutinating agents were isolated, which comprised 233 strains of influenza a virus. one hundred forty six (62.66%) of these strains were identified as h3n2, eighty one as ... | 1996 | 9127483 |
| immunogenicity and reactogenicity of influenza subunit vaccines produced in mdck cells or fertilized chicken eggs. | a tissue culture method using mdck cells grown under serum-free conditions was developed to produce an inactivated influenza subunit vaccine. the first clinical data suggest it to be equal to the conventional egg-derived influenza subunit vaccine. in a double-blind controlled trial, 2 groups (n = 57 each) of adult volunteers were immunized with experimental bivalent influenza subunit vaccine derived from either mdck cells or hens' eggs. each vaccine contained 15 microg of hemagglutinin of influe ... | 1997 | 9240689 |
| amantadine susceptibility in influenza a virus isolates: determination methods and lack of resistance in a canadian sample, 1991-94. | influenza a infections are an important cause of morbidity and mortality in the elderly and patients affected by chronic diseases or immunodeficiencies. treatment and prevention of infection in hospitals and nursing homes often involve the use of amantadine, but resistant viruses may arise. | 1997 | 9248657 |
| analysis of the host-specific haemagglutination of influenza a(h1n1) viruses isolated in the 1995/6 season. | two phenotypes of human influenza a(h1n1) virus are currently circulating in japan. one (group 1) agglutinates both chicken and goose red blood cells (crbc and grbc), the other (group 2) agglutinates grbc but not crbc. in the 1995/6 season, group 2 viruses accounted for 70% of the h1n1 viruses isolated in mdck cells. the 1995/6 viruses were located on two branches of the genetic tree. one branch contained both group 1 and group 2 viruses and the other branch contained only group 2 viruses. group ... | 1997 | 9440436 |
| isolation of influenza a(h3n2) virus with "o"-->"d" phase variation. | we report the isolation of two influenza a(h3n2) virus strains which were unable, in the first passages in mdck cell culture, to agglutinate chicken erythrocytes, though reacting with guinea pig and turkey red blood cells. this observation demonstrates that the occurrence of this phenomenon is not exclusive to influenza a(h1n1) viruses, as previously reported. in order to investigate the molecular basis of this phenomenon, we analysed the nucleotide sequence of the ha-1 region, presumed to be in ... | 1997 | 9498014 |
| postreassortment changes in influenza a virus hemagglutinin restoring ha-na functional match. | an important function of influenza virus neuraminidase (na) is the removal of sialic acid residues from virion components in order to prevent the aggregation of virus particles. in previous communications we have reported that reassortant viruses containing the na gene of a/ussr/90/77 (h1n1) virus and ha genes of h3, h4, h10, or h13 subtypes had a tendency to virion aggregation at 4 degrees c and that the virion clusters irreversibly dissociated after the treatment with bacterial neuraminidase. ... | 1998 | 9601502 |
| effects of host-dependent glycosylation of hemagglutinin on receptor-binding properties on h1n1 human influenza a virus grown in mdck cells and in embryonated eggs. | there is growing evidence that the receptor-binding characteristics of influenza viruses are affected by the host-dependent glycosylation of viral hemagglutinin (ha). to better understand these effects, we propagated two variants of the human influenza virus ussr/90/77 (which differed by the mutation asn131 reversible asp131 in the glycosylation sequon of their ha) in either embryonated chicken eggs or mdck cell. those variants were then compared for their ability to bind soluble receptor analog ... | 1998 | 9705910 |
| comparison of the ability of viral protein-expressing plasmid dnas to protect against influenza. | the ability of plasmid dna encoding various influenza viral proteins from the a/pr/8/34 (h1n1) virus to protect against influenza was compared in balb/c mice. the plasmid dna encoded hemagglutinin (ha), neuraminidase (na), matrix protein (m1), nucleoprotein (np) or nonstructural protein (ns1) in a chicken beta-actin-based expression vector (pcaggs). each dna was inoculated twice 3 weeks apart at a dose of 1 microgram per mouse by particle-mediated dna transfer to the epidermis (gene gun). seven ... | 1998 | 9711802 |
| m protein correlates with the receptor-binding specificity of haemagglutinin protein of reassortant influenza a (h1n1) virus. | from the reassortment experiments between a/aichi/4/92 and a/wsn/33 (wsn) (h1n1) viruses, two different phenotype viruses which contained the haemagglutinin (ha) gene from a/aichi/4/92 virus and the neuraminidase (na) gene from wsn virus were obtained. pw13 and pw15 viruses agglutinated chicken red blood cells (crbc), while pw10 and pw70 viruses did not. however, the expressed ha proteins of these viruses did not adsorb crbc. the difference in gene constellation between pw13, pw15 and pw10, pw70 ... | 1998 | 9780048 |
| effects of egg-adaptation on the receptor-binding properties of human influenza a and b viruses. | propagation of human influenza viruses in embryonated chicken eggs (ce) results in the selection of variants with amino acid substitutions near the receptor-binding site of the hemagglutinin (ha) molecule. to evaluate the mechanisms by which these substitutions enable human virus growth in ce, we studied the binding of 10 human influenza a (h1n1, h3n2) and b strains, isolated and propagated solely in mdck cells, and of their egg-adapted counterparts to preparations of cellular membranes, ganglio ... | 1999 | 10366560 |
| genetic analysis of mouse-adapted influenza a virus identifies roles for the na, pb1, and pb2 genes in virulence. | adaptation of the prototype a/fm/1/47 h1n1 strain to mice resulted in selection of the a/fm/1/47-ma variant with increased virulence. earlier analysis identified mutations in the ha and m1 genes that increase virulence in the mouse. complete sequence analysis identified mutations in the pb1, pb2, ha, na, and m1 genes. reassortants were produced between the parental fm and fm-ma strains to obtain viruses that differ due to combinations of mutant genes. to assess the relationship between virulence ... | 1999 | 10426210 |
| selection of receptor-binding variants of human influenza a and b viruses in baby hamster kidney cells. | cultivation of human influenza viruses in the allantoic cavity of embryonated chicken eggs leads to a selection of receptor-binding variants with amino acid substitutions on the globular head of the hemagglutinin (ha) molecule. such selection can be avoided by growing the human viruses in madin darby canine kidney (mdck) cells. in the present study, we tested whether baby hamster kidney (bhk) cells select receptor-binding mutants of human influenza viruses. after isolating h1n1, h3n2, and type b ... | 1999 | 10489338 |
| generation and characterization of reassortant influenza a viruses propagated in serum-free cultured mdck-sf1 cells. | the replacement of embryonated chicken eggs by tissue culture cells for the production of influenza vaccines is likely to take place in the near future. vaccines have already been produced in madin darby canine kidney (mdck) cells (brands et al, in this issue) and extensively tested in phase iii trials in humans (palache et al, in this issue) and it seems a matter of time before such vaccines will become available. for this reason, the generation of high-growth reassortants of influenza a virus ... | 1999 | 10494961 |
| selection of influenza virus mutants in experimentally infected volunteers treated with oseltamivir. | volunteers experimentally infected with influenza a/texas/36/91 (h1n1) virus and treated with the neuraminidase (na) inhibitor oseltamivir were monitored for the emergence of drug-resistant variants. two (4%) of 54 resistant viruses were detected by na inhibition assay among last-day isolates recovered from 54 drug recipients. they bore a substitution his274tyr in the na. hemagglutinin (ha) variants detected in the placebo group differed from the egg-adapted inoculum virus by virtue of amino aci ... | 2001 | 11170976 |
| [properties of influenza a and b, isolated from chick embryos and in mdck cell culture]. | mdck culture was used along with the traditional chicken embryonated eggs (cee) for improving the efficiency of isolation of epidemic influenza a and b viruses from clinical material. the number of influenza viruses isolated in both systems in epidemic seasons of 1997-1998 and 1998-1999 was as follows: 1 in mdck and 21 in cee for influenza a(h1n1), 56 and 7, respectively, for influenza a(h3n2), and 4 and 2 strains, respectively, for influenza b viruses. influenza a viruses were heterogeneous by ... | 2001 | 11233284 |
| binding of influenza type a viruses to group b streptococcus and haemagglutination by virus-bound bacteria. | we studied the bindings of human influenza a type viruses to group b streptococcus (gbs), types ia, ii, iii and iv, of sialic acid (sa)alpha2-3 linkage, using a/pr/8/34(h1n1) and a/memphis/1/71(h3n2). the viruses were found to bind to all types of gbs, with the exception of pr/8/34 for gbsii, and to elute from gbsia, iii and iv at 37 degrees c, except gbsii. electron microscopy confirmed these behaviours of the influenza viruses. the virus-binding capability of gbs types seemed to depend on the ... | 2000 | 11270858 |
| [study on the origin of influenza a(h1n2) virus ha and na genes]. | to determine the origins of the ha and na genes of new subtype (h1n2) of influenza a virus. | 2000 | 11503022 |
| hyperattenuated recombinant influenza a virus nonstructural-protein-encoding vectors induce human immunodeficiency virus type 1 nef-specific systemic and mucosal immune responses in mice. | we have generated recombinant influenza a viruses belonging to the h1n1 and h3n2 virus subtypes containing an insertion of the 137 c-terminal amino acid residues of the human immunodeficiency virus type 1 (hiv-1) nef protein into the influenza a virus nonstructural-protein (ns1) reading frame. these viral vectors were found to be genetically stable and capable of growing efficiently in embryonated chicken eggs and tissue culture cells but did not replicate in the murine respiratory tract. despit ... | 2001 | 11533153 |
| isolation from turkey breeder hens of a reassortant h1n2 influenza virus with swine, human, and avian lineage genes. | type a influenza viruses can infect a wide range of birds and mammals, but influenza in a particular species is usually considered to be species specific. however, infection of turkeys with swine h1n1 viruses has been documented on several occasions. this report documents the isolation of an h1n2 influenza virus from a turkey breeder flock with a sudden drop in egg production. sequence analysis of the virus showed that it was a complex reassortant virus with a mix of swine-, human-, and avian-or ... | 2002 | 11922322 |
| comparison of embryonated chicken eggs with mdck cell culture for the isolation of swine influenza virus. | embryonated chicken eggs (ece) and the madin-darby canine kidney (mdck) cell line were compared for isolation of swine influenza virus (siv) from nasal swabs and tissue samples. samples originated from 30 pigs experimentally inoculated with 2 x 106 to 2 x 10(7) embryo infectious dose 50% (eid50)/ml of swine influenza strain a/swine/indiana/1726/88 (h1n1). the results were analyzed with mcnemar's chi-squared test for symmetry. the results indicated that more samples were siv-positive with ece tha ... | 2002 | 11989733 |
| influenza activity in china: 1998-1999. | during 1989-1999, influenza a h3n2 and h1n1 subtypes and b type viruses were still co-circulating in human population in china, while influenza a (h3n2) virus was predominant strain. the two antigenically and genetically distinguishable strains of influenza b virus were also still co-circulating in men in southern china. the antigenic analysis indicated that most of the h3n2 viruses were a/panama/2007/99 (h3n2)-like strain, the most of the h1n1 viruses were antigenically similar to a/beijing/262 ... | 2002 | 12110253 |
| eight-plasmid system for rapid generation of influenza virus vaccines. | the antigenic variation of influenza a virus hemagglutinin (ha) and neuraminidase (na) glycoproteins requires frequent changes in vaccine formulation. the classical method of creating influenza virus seed strains for vaccine production is to generate 6 + 2 reassortants that contain six genes from a high-yield virus, such as a/pr/8/34 (h1n1) and the ha and na genes of the circulating strains. the techniques currently used are time-consuming because of the selection process required to isolate the ... | 2002 | 12163268 |
| [the feature of influenza virus activity and genetic characterization of ha1 gene of influenza a h3n2 viruses isolated from 1994-1997 in shenzhen]. | to understand the feature of influenza virus activity and genetic characterization of ha1 gene of influenza a h3n2 viruses isolated in recently years in shenzhen. | 1999 | 12569759 |
| the influenza virus gene pool in a poultry market in south central china. | we surveyed influenza activity in a live poultry market in central china for 16 months, isolating viruses from 1% of 6360 fecal samples. we obtained multiple h3n6, h9n2, h2n9, h3n3, and h4n6 isolates and single h1n1 and h3n2 isolates. two distinct h3 molecules were identified; other hemagglutinin subtypes were phylogenetically homogeneous. the h3n6 viruses (9 genotypes) and h9n2 viruses (4 genotypes) were genetically heterogeneous, whereas the h2n9, h3n3 and h4n6 viruses had single genotypes. th ... | 2003 | 12573572 |
| distinct host range of influenza h3n2 virus isolates in vero and mdck cells is determined by cell specific glycosylation pattern. | influenza a viruses were isolated in vero, mdck cells and chicken embryos. in contrast to mdck-derived variants all h3n2 isolates obtained in vero cells neither agglutinated chicken erythrocytes nor grew in chicken eggs. these host range differences of h3n2 vero and mdck isolates were noticed even in the absence of amino acid substitutions in the ha1 molecule. evaluation of ha glycosylation pattern by treatment with endoglycosidases h and f revealed that vero-variants contained more oligosacchar ... | 2003 | 12667817 |
| baculovirus induces an innate immune response and confers protection from lethal influenza virus infection in mice. | a recombinant baculovirus expressing the hemagglutinin gene of the influenza virus, a/pr/8/34 (h1n1), under the control of the chicken beta-actin promoter, was constructed. to determine the induction of protective immunity in vivo, mice were inoculated with the recombinant baculovirus by intramuscular, intradermal, i.p., and intranasal routes and then were challenged with a lethal dose of the influenza virus. intramuscular or i.p. immunization with the recombinant baculovirus elicited higher tit ... | 2003 | 12874198 |
| receptor-binding properties of modern human influenza viruses primarily isolated in vero and mdck cells and chicken embryonated eggs. | to study the receptor specificity of modern human influenza h1n1 and h3n2 viruses, the analogs of natural receptors, namely sialyloligosaccharides conjugated with high molecular weight (about 1500 kda) polyacrylamide as biotinylated and label-free probes, have been used. viruses isolated from clinical specimens were grown in african green monkey kidney (vero) or madin-darby canine kidney (mdck) cells and chicken embryonated eggs. all vero-derived viruses had hemagglutinin (ha) sequences indistin ... | 2003 | 12954214 |
| generation and characterization of a cold-adapted influenza a h9n2 reassortant as a live pandemic influenza virus vaccine candidate. | h9n2 subtype influenza a viruses have been identified in avian species worldwide and were isolated from humans in 1999, raising concerns about their pandemic potential and prompting the development of candidate vaccines to protect humans against this subtype of influenza a virus. reassortant h1n1 and h3n2 human influenza a viruses with the internal genes of the influenza a/ann arbor/6/60 (h2n2) (aa) cold-adapted (ca) virus have proven to be attenuated and safe as live virus vaccines in humans. u ... | 2003 | 14505926 |
| preparation of a standardized, efficacious agricultural h5n3 vaccine by reverse genetics. | options for the control of emerging and reemerging h5n1 influenza viruses include improvements in biosecurity and the use of inactivated vaccines. commercially available h5n2 influenza vaccine prevents disease signs and reduces virus load but does not completely prevent virus shedding after challenge with h5n1 virus. by using reverse genetics, we prepared an h5n3 vaccine whose hemagglutinin is 99.6% homologous to that of a/ck/hk/86.3/02 (h5n1). we used the internal genes of a/pr/8/34 and the h5 ... | 2003 | 14554086 |
| the quest of influenza a viruses for new hosts. | there is increasing evidence that stable lineages of influenza viruses are being established in chickens. h9n2 viruses are established in chickens in eurasia, and there are increasing reports of h3n2, h6n1, and h6n2 influenza viruses in chickens both in asia and north america. surveillance in a live poultry market in nanchang, south central china, reveals that influenza viruses were isolated form 1% of fecal samples taken from healthy poultry over the course of 16 months. the highest isolation r ... | 2003 | 14575076 |
| generation and characterization of an h9n2 cold-adapted reassortant as a vaccine candidate. | h9n2 subtype avian influenza viruses have been identified in avian species worldwide, and infections in pigs were confirmed in hong kong in 1998. subsequently, h9n2 viruses were isolated from two children in hong kong in 1999, and five human infections were reported from china, raising the possibility that h9n2 viruses pose a potential pandemic threat for humans. these events prompted us to develop a vaccine candidate to protect humans against this subtype of influenza a viruses. reassortant h1n ... | 2003 | 14575127 |
| pathogenicity and immunogenicity of influenza viruses with genes from the 1918 pandemic virus. | the 1918 influenza a h1n1 virus caused the worst pandemic of influenza ever recorded. to better understand the pathogenesis and immunity to the 1918 pandemic virus, we generated recombinant influenza viruses possessing two to five genes of the 1918 influenza virus. recombinant influenza viruses possessing the hemagglutinin (ha), neuraminidase (na), matrix (m), nonstructural (ns), and nucleoprotein (np) genes or any recombinant virus possessing both the ha and na genes of the 1918 influenza virus ... | 2004 | 14963236 |
| evidence of the concurrent circulation of h1n2, h1n1 and h3n2 influenza a viruses in densely populated pig areas in spain. | this paper reports on a serological and virological survey for swine influenza virus (siv) in densely populated pig areas in spain. the survey was undertaken to examine whether the h1n2 siv subtype circulates in pigs in these areas, as in other european regions. six hundred sow sera from 100 unvaccinated breeding herds across northern and eastern spain were examined using haemagglutination inhibition (hi) tests against h1n1, h3n2 and h1n2 siv subtypes. additionally, 225 lung samples from pigs wi ... | 2006 | 15914047 |
| characterization of the reconstructed 1918 spanish influenza pandemic virus. | the pandemic influenza virus of 1918-1919 killed an estimated 20 to 50 million people worldwide. with the recent availability of the complete 1918 influenza virus coding sequence, we used reverse genetics to generate an influenza virus bearing all eight gene segments of the pandemic virus to study the properties associated with its extraordinary virulence. in stark contrast to contemporary human influenza h1n1 viruses, the 1918 pandemic virus had the ability to replicate in the absence of trypsi ... | 2005 | 16210530 |
| [the deletion of nucleotides of ns gene from 263 to 277 of h5n1 increases viral virulence in chicken]. | since 2000, more and more ns fragment of h5n1 subtype influenza a virus had a unique deletion of nuleotides from 263 to 277. in order to investigate the biological significance of the mutation, four recombinants, rwsn-848, rwsn-m848, rwsn-248 and rwsn-m248, were generated via eight-plasmid reverse genetic system. these reassortants had the same inner gene and outer gene derived from a/wsn/33(h1n1) and a/d/sd/04(h5n1), respectively. but their ns genes were different. rwsn-m248 and rwsn-848 were i ... | 2006 | 16736596 |
| differential expression of chemokines and their receptors in adult and neonatal macrophages infected with human or avian influenza viruses. | in 1997, avian influenza virus h5n1 was transmitted directly from chicken to human and resulted in a severe disease that had a higher mortality rate in adults than in children. the characteristic mononuclear leukocyte infiltration in the lung and the high inflammatory response in h5n1 infection prompted us to compare the chemokine responses between influenza virus-infected adult and neonatal monocyte-derived macrophages (mdms). the effects of avian influenza virus a/hong kong/483/97 (h5n1) (h5n1 ... | 2006 | 16741883 |
| amantadine resistance among porcine h1n1, h1n2, and h3n2 influenza a viruses isolated in germany between 1981 and 2001. | this study was designed to gain insight into amantadine susceptibility of porcine influenza a viruses isolated in germany between 1981 and 2001. the 12 studied h1n1, h1n2, and h3n2 porcine influenza virus strains were isolated in chicken eggs and passaged once in mdck cells. plaque reduction assays were applied to examine virus susceptibility to amantadine. genotyping was used to confirm drug resistance. in the results of these antiviral studies, only 3 of the 12 isolates were shown to be amanta ... | 2006 | 16809934 |
| [application of single radial hemolysis technique for diagnosis of influenza a (h5n1)]. | to understand the optimal condition of single radial hemolysis (srh) for diagnosis of avian influenza a (h5n1) virus in order that srh could be performed in general laboratories. | 2006 | 16816850 |
| reassortment and modification of hemagglutinin cleavage motif of avian/wsn influenza viruses generated by reverse genetics that correlate with attenuation. | avian influenza associated with h9n2 and h5n1 subtypes of avian influenza viruses (aivs) has raised great concerns in china. to study this problem, reverse genetics has been employed. three reassortants, rgh9n2, rgh5n1 and rgh5n2, were prepared and compared. their hemagglutinin (ha) and neuraminidase (na) genes originated from chinese aiv isolates of h9n2 or h5n1 subtype, while the rest of their genes were derived from a/wsn/33(h1n1) virus (wsn). in the h5 ha reassortants, the multibasic cleavag ... | 2006 | 17177609 |
| effect of gene constellation and postreassortment amino acid change on the phenotypic features of h5 influenza virus reassortants. | reassortants between a low-pathogenic avian influenza virus strain a/duck/primorie/2621/2001 (h5n2) and a high-yield human influenza virus strain a/puerto rico/8/34 (h1n1) were generated, genotyped and analyzed with respect to their yield in embryonated chicken eggs, pathogenicity for mice, and immunogenicity. a reassortant having ha and na genes from a/duck/primorie/2621/2001 virus and 6 genes from a/puerto rico/8/34 virus (6:2 reassortant) replicated efficiently in embryonated chicken eggs, th ... | 2007 | 17294090 |
| properties of h7n7 influenza a virus strain sc35m lacking interferon antagonist ns1 in mice and chickens. | non-structural protein ns1 of influenza a virus counteracts the host immune response by blocking the synthesis of type i interferon (ifn). as deletion of the complete ns1 gene has to date been reported only in the human h1n1 strain a/pr/8/34, it remained unclear whether ns1 is a non-essential virulence factor in other influenza a virus strains as well. in this report, the properties of ns1-deficient mutants derived from strain sc35m (h7n7) are described. a mutant of sc35m that completely lacks t ... | 2007 | 17412966 |
| epitope mapping of the hemagglutinin molecule of a highly pathogenic h5n1 influenza virus by using monoclonal antibodies. | we mapped the hemagglutinin (ha) antigenic epitopes of a highly pathogenic h5n1 influenza virus on the three-dimensional ha structure by characterizing escape mutants of a recombinant virus containing a/vietnam/1203/04 (h5n1) deltaha and neuraminidase genes in the genetic background of a/puerto rico/8/34 (h1n1) virus. the mutants were selected with a panel of eight anti-ha monoclonal antibodies (mabs), seven to a/vietnam/1203/04 (h5n1) virus and one to a/chicken/pennsylvania/8125/83 (h5n2) virus ... | 2007 | 17881439 |
| [tetravaccine--new fundamental approach to prevention of influenza pandemic]. | according to opinion of who's experts, development and use of tetravaccine, which contains both interdemic and pandemic (h5n1) serotypes of influenza viruses, is one of the most promising approaches to control possible influenza pandemic. results of recently obtained data from clinical trials allowed experts from who to make a conclusion that protective immunity against avian influenza virus can be achieved after 2-doses immunization, when the immune system will be primed to hemagglutinin after ... | 2007 | 17882832 |
| development and evaluation of an influenza virus subtype h7n2 vaccine candidate for pandemic preparedness. | influenza virus of the h7n2 subtype has been introduced into noncommercial poultry in the united states, and this probably resulted in incidents of transmission of h7n2 virus to humans, documented in 2002 and 2003. this virus could be considered a potential threat to public health if it acquired person-to-person transmissibility. a favored approach for global pandemic preparedness includes development of prepandemic vaccines for any potential pandemic virus. to this end, we created a high-growth ... | 2007 | 17913860 |
| chicken lung lectin is a functional c-type lectin and inhibits haemagglutination by influenza a virus. | many proteins of the calcium-dependent (c-type) lectin family have been shown to play an important role in innate immunity. they can bind to a broad range of carbohydrates, which enables them to interact with ligands present on the surface of micro-organisms. we previously reported the finding of a new putative chicken lectin, which was predominantly localized to the respiratory tract, and thus termed chicken lung lectin (cll). in order to investigate the biochemical and biophysical properties o ... | 2008 | 18261862 |
| virulence of h5n1 avian influenza virus enhanced by a 15-nucleotide deletion in the viral nonstructural gene. | more and more h5n1 subtype avian influenza viruses possessing a 15-nucleotide (15-nt) deletion in the viral nonstructural protein (ns) gene from position 263 to 277 have emerged since 2000. in order to investigate the biological significance of this deletion, two pairs of h5n1 reassortants designated as rwsn-sd versus rwsn-msd and rwsn-yz versus rwsn-myz were generated by reverse genetics technique. these recombinant viruses shared the same inner genes of pb1, pb2, pa, np, and m from strain a/ws ... | 2008 | 18317917 |
| [optimization of the gene composition of influenza h5 virus hemagglutinin-containing reassortants and their efficacy in immune cross-protection experiments]. | the reassortant described in the authors' previous paper contained 6 genes originating from the high-yield virus a/puerto rico/8/34 (h1n1) and the genes of hemagglutinin (ha) and neuraminidase (na) of the low-pathogenic avian influenza a/duck/primorie/2621/2001 (h5n2) (6:2 reassortant). the reassortant was used for the backcrossing with the parent avian virus in order to optimize the gene composition. genotyping of the highest-yield second-generation reassortment indicated that it had obtained t ... | 2008 | 18318131 |
| development of eurasian h7n7/pr8 high growth reassortant virus for clinical evaluation as an inactivated pandemic influenza vaccine. | avian-to-human transmission of the high pathogenicity (hp) h7n7 subtype avian influenza viruses in the netherlands during 2003 caused zoonotic infections in 89 people, including a case of acute fatal respiratory distress syndrome. public health emergency preparedness against h7n7 avian influenza viruses with pandemic potential includes the development of vaccine candidate viruses. in order to develop a high growth reassortant vaccine candidate virus, low pathogenicity (lp) a/mallard/netherlands/ ... | 2008 | 18336962 |
| deviation from the random distribution pattern of influenza a virus gene segments in reassortants produced under non-selective conditions. | high-frequency reassortment of gene segments is characteristic for influenza viruses, and it is considered to be of significance for the origin of pandemic influenza. in order to analyze whether the segregation of genes in the reassortants is random, or it deviates from the random pattern, we inoculated embryonated chicken eggs simultaneously with two influenza viruses, a/wsn/33 (h1n1) and a/duck/ czechoslovakia/56 (h4n6), at a high multiplicity of infection. the virus yield was used for plaque ... | 2008 | 18414973 |
| generation and evaluation of the trivalent inactivated reassortant vaccine using human, avian, and swine influenza a viruses. | reassortant technology was used to obtain three interspecific reassortant influenza viruses using three influenza viruses of a/puerto rico/8/34(h1n1), a/swine/hebei/1/2005(h3n2) and a/chicken/guangdong/126/2002(h9n2). the high-growth reassortant strains were h9/pr8, h3/h9n2 and h1/h9n2 that contained hemagglutinin (ha) and neuraminidase (na) genes from the inactivated parental viruses and the other 6 internal genes from the live parental viruses. the trivalent formalin-inactivated vaccine, conta ... | 2008 | 18448208 |
| mdck-siat1 cells show improved isolation rates for recent human influenza viruses compared to conventional mdck cells. | the ability to isolate and propagate influenza virus is an essential tool for the yearly surveillance of circulating virus strains and to ensure accurate clinical diagnosis for appropriate treatment. the suitability of mdck-siat1 cells, engineered to express increased levels of alpha-2,6-linked sialic acid receptors, as an alternative to conventional mdck cells for isolation of circulating influenza virus was assessed. a greater number of influenza a (h1n1 and h3n2) and b viruses from stored hum ... | 2008 | 18480230 |
| asparagine 631 variants of the chicken mx protein do not inhibit influenza virus replication in primary chicken embryo fibroblasts or in vitro surrogate assays. | whether chicken mx inhibits influenza virus replication is an important question with regard to strategies aimed at enhancing influenza resistance in domestic flocks. the asn631 polymorphism of the chicken mx protein found in the shamo (shk) chicken line was previously reported to be crucial for the antiviral activity of this highly polymorphic chicken gene. our aims were to determine whether cells from commercial chicken lines containing asn631 alleles were resistant to influenza virus infectio ... | 2008 | 18508886 |
| domestic pigs have low susceptibility to h5n1 highly pathogenic avian influenza viruses. | genetic reassortment of h5n1 highly pathogenic avian influenza viruses (hpai) with currently circulating human influenza a strains is one possibility that could lead to efficient human-to-human transmissibility. domestic pigs which are susceptible to infection with both human and avian influenza a viruses are one of the natural hosts where such reassortment events could occur. virological, histological and serological features of h5n1 virus infection in pigs were characterized in this study. two ... | 2008 | 18617994 |
| an improved embryonated chicken egg model for the evaluation of antiviral drugs against influenza a virus. | influenza is a serious global public health problem and an economic burden. with the continual emergence of new influenza a virus strains, new antiviral drugs are needed urgently. in this study, an improved embryonated chicken egg model for evaluating antiviral activity against influenza a virus was developed. in the model, the influenza a virus was injected into the allantoic cavity and ribavirin was injected into the albumen of the egg. the levels of influenza a virus in the allantoic fluid wa ... | 2008 | 18652846 |
| seroprevalence and risk factors for influenza a viruses in pigs in peninsular malaysia. | following a series of h5n1 cases in chickens and birds in a few states in malaysia, there was much interest in the influenza a viruses subtypes that circulate among the local pig populations. pigs may act as a mixing vessel for avian and mammal influenza viruses, resulting in new reassorted viruses. this study investigated the presence of antibodies against influenza h1n1 and h3n2 viruses in pigs from peninsular malaysia using herdcheck swine influenza h1n1 and h3n2 antibody test kits. at the sa ... | 2008 | 18667027 |
| [the rescue of h1n1 subtype swine influenza virus]. | the swine influenza virus (siv) strain a/swine/tianjin/01/2004(h1n1) (a/s/tj/04) was rescued successfully by an eight-plasmid rescue system. the cdnas of siv 8 gene segments were synthesized by rt-pcr and cloned into the rna polymerase i/ii bidirection expression vector phw2000 independently, resulting in 8 recombinant plasmids. the 8 recombinant plasmids were cotransfected into cos-1 cell, 30 h later tpck-trypsin was added to 0.5 microg/ml. the cos-1 cell and supernatant were harvested 48 h aft ... | 2008 | 18724708 |
| [epidemic strains influenza viruses a and b in the 2005-2006 season in russia]. | investigations indicated that the epidemic upsurge of influenza morbidity in the 2005-2006 season in russia was caused by the active circulation of influenza viruses a and b. the center for ecology and epidemiology of influenza, d. i. ivanovsky institute of virology, russian academy of medical sciences, studied 182 epidemic strains. a hundred and thirteen influenza viruses a(h3n2) were similar to the reference a/california/07/2004 or were its antigenic variants. thirteen influenza virus a(h1n1) ... | 2008 | 18756810 |
| [influenza vaccine]. | the efficacy of seasonal influenza vaccines is not always high. however, this is not due to the vaccine itself, rather due to the viral frequent antigenic changes. instead of the current chicken embryonated egg-based strategy for vaccine production, the use of the cell culture-based one may increase its productivity as well as efficacy. in addition, pre-pandemic h5n1 vaccines are now being stockpiled worldwide, although their total vaccine doses are limited due to their low productivity and immu ... | 2008 | 18939506 |
| post-reassortment amino acid change in the hemagglutinin of a human-avian influenza h5n1 reassortant virus alters its antigenic specificity. | it was shown earlier that the reassortant influenza virus having hemagglutinin (ha) gene of a/duck/primorie/2621/2001 (h5n2) virus and 7 genes of a/puerto rico/8/34 (h1n1) virus produced low yields in embryonated chicken eggs. we found that a variant reassortant selected by serial passages in eggs produced higher yields than the initial reassortant. the variant reassortant had an amino acid substitution in the hemagglutinin n244d (h3 numbering). in this report we demonstrated that the post-reass ... | 2008 | 18999893 |
| the human h5n1 influenza a virus polymerase complex is active in vitro over a broad range of temperatures, in contrast to the wsn complex, and this property can be attributed to the pb2 subunit. | influenza a virus (iav) replicates in the upper respiratory tract of humans at 33 degrees c and in the intestinal tract of birds at close to 41 degrees c. the viral rna polymerase complex comprises three subunits (pa, pb1 and pb2) and plays an important role in host adaptation. we therefore developed an in vitro system to examine the temperature sensitivity of iav rna polymerase complexes from different origins. complexes were prepared from human lung epithelial cells (a549) using a novel adenov ... | 2008 | 19008377 |
| pb2 protein of a highly pathogenic avian influenza virus strain a/chicken/yamaguchi/7/2004 (h5n1) determines its replication potential in pigs. | it has been shown that not all but most of the avian influenza viruses replicate in the upper respiratory tract of pigs (h. kida et al., j. gen. virol. 75:2183-2188, 1994). it was shown that a/chicken/yamaguchi/7/2004 (h5n1) [ck/yamaguchi/04 (h5n1)] did not replicate in pigs (n. isoda et al., arch. virol. 151:1267-1279, 2006). in the present study, the genetic basis for this host range restriction was determined using reassortant viruses generated between ck/yamaguchi/04 (h5n1) and a/swine/hokka ... | 2009 | 19052090 |