characterization and immunological properties of influenza a virus nucleoprotein (np): cell-associated np isolated from infected cells or viral np expressed by vaccinia recombinant virus do not confer protection.a nucleoprotein (np) preparation purified from the chorioallantoic membrane of chicken eggs infected with fowl plague virus (a/fpv/rostock/34, h7n1) yielded, in addition to the commonly known 56k protein, a 42k component that could not be detected in virus particles. after testing with a series of np-specific monoclonal antibodies it was found that some reacted with both proteins and others were bound only by the 56k protein. among both types of np-specific monoclonal antibodies only a limited n ...19901693165
amantadine selection of a mutant influenza virus containing an acid-stable hemagglutinin glycoprotein: evidence for virus-specific regulation of the ph of glycoprotein transport vesicles.mutants of influenza rostock virus (h7n1 subtype) were selected for resistance to amantadine hydrochloride at concentrations of the antiviral drug known to affect the function of the virus m2 transmembrane protein. sequence analysis revealed that three mutants had no changes in m2 but contained a lysine to isoleucine substitution in the hemagglutinin (ha) membrane glycoprotein at position 58 of ha2. the mutant viruses were found to fuse membranes at a ph value 0.7 lower than wild type and to exh ...19911763066
immunologic response to the influenza virus neuraminidase is influenced by prior experience with the associated viral hemagglutinin. i. studies in human vaccinees.analysis of an earlier study of h3n2 and h7n2 inactivated influenza vaccines in schoolchildren demonstrated a greater viral neuraminidase (na) immunogenicity of the vaccine containing the h7 hemagglutinin (ha) antigen to which they had not been primed, despite the lesser na antigen content of that vaccine. thus, prior experience with the influenza viral ha appeared to have a negative influence on immune response to na, the associated external glycoprotein, presumably on the basis of intermolecul ...19873571981
a reassortant between influenza a viruses (h7n2) synthesizing an enzymatically inactive neuraminidase at 40 degrees which is not incorporated into infectious particles.cells infected with a reassortant (113/ho, h7n2) between a/fowl plague/rostock/34 (fpv, h7n1) and a/hong kong/1/68 (h3n2) carrying rna segments 1 and 6 of the hong kong virus and the residual genes of fpv, synthesized at 40 degrees a neuraminidase (na) which is enzymatically not active and which is not incorporated into infectious particles. at 40 degrees na accumulates in the rough endoplasmic reticulum. it contains mainly carbohydrate side chains of the mannose type, and fucose is only scarcel ...19863952990
inhibition of replication of avian influenza viruses by the neuraminidase inhibitor 4-guanidino-2,4-dideoxy-2,3-dehydro-n-acetylneuraminic acid.the sialidase inhibitor 4-guanidino-2,4-dideoxy-2,3-dehydro-n-acetylneuraminic acid (4-guanidino-neu5ac2en), designed with computer assistance and knowledge of the crystal structure of influenza virus neuraminidase, has shown antiviral effects in animal models of human influenza (m. von itzstein et al., nature, 363, 418-423, 1993). here we demonstrate that the compound efficiently inhibits the enzyme activity of all nine subtypes of avian influenza a neuraminidase in vitro. when administered int ...19957571401
possible waterborne transmission and maintenance of influenza viruses in domestic ducks.two duck farms in hong kong were examined monthly for 1 year for the occurrence and persistence of influenza viruses within the duck communities. the predominant virus in one community was h3n2, a virus antigenically related to the pandemic hong kong strain. this virus was isolated monthly throughout the year from feces or pond water or both, indicating a cycle of waterborne transmission. viruses of the same antigenic combination were isolated 1 and 2 years after the last sampling occasion, impl ...19827055370
sequence of the neuraminidase gene of an avian influenza a virus (a/parrot/ulster/73, h7n1).the complete sequence of the neuraminidase (na) gene of the influenza a strain a/parrot/ ulster /73 ( h7n1 ) has been determined after reverse transcribing and cloning it into the pbr322 plasmid, followed by subcloning into m13 vectors and sequencing with dideoxynucleotide chain terminators. the gene consists of 1458 nucleotides and codes for a protein of 469 amino acids. the neuraminidase has seven potential glycosylation sites. according to the molecular weight as determined by electrophoretic ...19846328743
further studies on the role of neuraminidase and the mechanism of low ph dependence in influenza virus-induced membrane fusion.the role of neuraminidase and the mechanism of low ph dependence in influenza virus-induced membrane fusion have been studied further using fowl plague virus (fpv, h7n1). two specific anti-fpv neuraminidase antisera obtained from chickens immunized with recombinant virus strains inhibited viral neuraminidase activity without influencing its haemagglutinating activity. these sera totally inhibited the fpv-induced fusion of erythrocytes and partially reduced haemolysis. but both fusion and haemoly ...19853968541
nucleotide sequence analysis of the nucleoprotein gene of an avian and a human influenza virus strain identifies two classes of nucleoproteins.the nucleotide sequences of rna segment 5 of an avian influenza a virus, a/mallard/ny/6750/78 (h2n2), and a human influenza a virus, a/udorn/307/72 (h3n2), were determined and the deduced amino acid sequences of the nucleoprotein (np) of these viruses were compared to two other avian and two other human influenza a np sequences. the results indicated that there are separate classes of avian and human influenza a np genes that can be distinguished on the basis of sites containing amino acids spec ...19863788059
studies on the temperature sensitivity of influenza a virus reassortants nonpathogenic for chicken.influenza a virus reassortants which are nonpathogenic for chickens are like mammalian influenza a viruses in that they are temperature sensitive for growth at 41 degrees c. we have investigated the mechanism of this temperature sensitivity using reassortants between the two highly pathogenic strains a/fpv/rostock/34 (fpv, h7n1) and a/turkey/england/63 (te, h7n3). these reassortants show a strict correlation between the pathogenicity for chickens and the constellation of the genes coding for the ...19863751286
quantitative relationships between an influenza virus and neutralizing this quantitative study of the interaction of influenza virus with neutralizing antibody we have determined the maximum number of antibody molecules which can bind to the haemagglutinin (ha) of native influenza a/fpv/rostock/34 (h7n1) particles in aqueous suspension and the minimum number which is required to cause neutralization. using radiolabelled immunoglobulins approximately one igg molecule, whether of monoclonal or polyclonal origin, binds per ha spike under conditions of antibody satu ...19873617501
[change in the influenza virus upon multiplication in the presence of high concentrations of remantadine].it was established that classical fowl plague virus rostock (h7n1) propagated in culture to which 10-25 micrograms/ml of remantadine had been added differed from the original fpv and its remantadine-resistant variant by markedly reduced infectious and hemagglutinating activity and, to a lesser extent, neuraminidase activity, lower amounts of m protein and hemagglutinin, incomplete cleavage of hemagglutinin, and significant loss of spikes on the virion surface.19892728406
the critical cut-off temperature of avian influenza viruses.we have measured the pathogenicity for 6-week-old chicks of infection by h7 avian influenza viruses. one virus, strain s3 from a/fpv/rostock/34(h7n1) showed a temperature sensitive phenotype at 41.5 degrees c and reduced pathogenicity. by analysis of reassortants made between virus s3 and a/fpv/dobson/27(h7n7), a fully pathogenic virus, two conclusions arise. (1) the critical cut-off temperature for avian influenza virus in 6-week-old chicks is 41.5 degrees. (2) rna segment 1 of virus s3 is resp ...19902077784
structure and assembly of hemagglutinin mutants of fowl plague virus with impaired surface transport.five temperature-sensitive mutants of influenza virus a/fpv/rostock/34 (h7n1), ts206, ts293, ts478, ts482, and ts651, displaying correct hemagglutinin (ha) insertion into the apical plasma membrane of mdck cells at the permissive temperature but defective transport to the cell surface at the restrictive temperature, have been investigated. nucleotide sequence analysis of the ha gene of the mutants and their revertants demonstrated that with each mutant a single amino acid change is responsible f ...19921738202
carbohydrate masking of an antigenic epitope of influenza virus haemagglutinin independent of oligosaccharide size.comparison of the haemagglutinins (ha) of the pathogenic avian influenza viruses a/fpv/dutch/27 (h7n7) and a/fpv/rostock/34 (h7n1) revealed 94.7% nucleotide and 93.8% amino acid sequence homologies. six of the seven n-glycosidic oligosaccharides of the rostock ha are at the same positions as the six carbohydrates of the dutch strain. the additional oligosaccharide side chain of the rostock strain, which is of the complex type, is attached to asparagine149 in antigenic epitope b. the accessibilit ...19921379858
inhibition of influenza virus protein synthesis by a plant preparation from geranium sanguineum l.a polyphenolic complex (pc) with antiviral properties has been isolated from the bulgarian medicinal plant geranium sanguineum l. a study was undertaken to investigate the effect of pc on virus-specific protein synthesis in influenza virus-infected cells. the expression of viral glycoproteins on the surface of chick embryo fibroblasts infected with virus a/fpv, strain rostock (h7n1) was suppressed. virus protein synthesis was selectively inhibited as shown by sds polyacrylamide gel electrophores ...19957572469
carbohydrates of influenza virus. v. oligosaccharides attached to individual glycosylation sites of the hemagglutinin of fowl plague virus.the carbohydrate side chains of the hemagglutinin of fowl plague virus (a/fpv/rostock/34 (h7n1] have been localized by a procedure involving fragmentation of the polypeptide with cyanogen bromide and various proteases. the positions of the fragments were determined by radioactive labeling of the sugars and of specific amino acids. side chains of the complex type i are attached to asparagine residues 12, 28, 123, 149, and 478. a mannose-rich (type ii) side chain is linked to asparagine 406. aspar ...19846422625
sequence of the nucleoprotein gene of influenza a/parrot/ulster/73.the nucleotide sequence of the nucleoprotein (np) gene of the avian influenza a virus strain a/parrot/ulster/73 (h7n1) has been determined. the gene (rna segment 5) consists of 1565 bases. the only large open reading frame of the complementary rna codes for a protein of 498 amino acids. a comparison of its sequence with that of three other influenza virus nps shows that the np of the parrot ulster strain, although closely related to the np of the other avian strain (a/fpv/rostock/34), is definit ...19854024728
interplay between lipids and viral glycoproteins during hemolysis and fusion by influenza virus.since mixtures of lipids alone are known to elicit membrane fusion without participation of fusion proteins, the role of viral lipids in the so-called virus-induced hemolysis and cell fusion has been investigated, using as a model the fowl plague virus (influenza a/fpv/rostock/h7n1). the experiments were planned in a way that allowed quantitative modification of viral lipids without changing envelope glycoproteins. under the conditions employed, cholesterol oxidase of nocardia erythropolis and p ...19863759942
one defective interfering particle per cell prevents influenza virus-mediated cytopathology: an efficient assay system.the titre of defective interfering (di) influenza virus measured by an assay based on the inhibition of cytopathology caused by a/wsn (h1n1) influenza virus in mdck cells was 320,000-fold greater than titres measured by inhibition of infectious centre formation. interference was less in other types of cell. by electron microscopy, we have shown that the ratio between physical particles and di units in preparations of the di virus was approximately unity, which suggested that one or few di partic ...19883385408
location of influenza virus m, np and ns1 proteins in microinjected cells.when microinjected as cloned dna, the nucleoprotein (np) of influenza virus a/nt/60/68 (h3n2) accumulated in the nuclei of xenopus laevis oocytes, and cultured cells of rodent and primate origin. this accumulation appeared to be specific and a property of the np itself (or conceivably np in association with unknown cellular constituents) since no other influenza virus components were present in dna-injected cells. in the oocyte nucleus, clonally derived np achieved an eightfold concentration ove ...19852932535
morphological studies of the neutralization of influenza virus by igm.quantitative relationships between neutralization, aggregation and attachment to monolayers of chick embryo fibroblast (cef) cells have been studied using a constant amount of influenza a/fowl plague virus/rostock/34 (h7n1) and varying amounts of purified mouse polyclonal igm directed against the haemagglutinin, the major viral neutralization antigen. there are two major types of interaction. (i) at low concentrations of igm there is aggregation of virus, but no neutralization provided that the ...19902230737
assessment of the ability of ratite-origin influenza viruses to infect and produce disease in rheas and chickens.pathobiologic characteristics were determined for three mildly pathogenic (mp) ratite-origin avian influenza viruses (aivs). ratite-origin aivs produced respiratory disease in rheas, and virus was reisolated from oropharyngeal and cloacal swabs on days 2-6 postinoculation. inoculation of two ratite-origin aivs in the upper respiratory tract of chickens resulted in viral infections, but the mean chicken infectious dose (cid50) for a/emu/texas/39924/93 (h5n2) (emu/texas) virus was 500-fold lower t ...19968790896
on the penetration mechanism of influenza viruses.the envelopes of influenza viruses contain in addition to lipids also two glycoproteins, the hemagglutinin and the neuraminidase, that are responsible for the adsorption, receptor splitting, penetration and budding processes of these viruses. in this article, hypotheses presented in the past with regard to the virus penetration are reconsidered. based on results obtained with the fowl plague virus (influenza a/fpv/rostock/34, h7n1) and mdck-cells, we conclude that a fusion between the viral enve ...19911930099
[preparative isolation of basic structural proteins of the influenza virus].the schemes for preparative electrophoretic isolation and purification of major proteins from influenza virus are described. the viral envelope protein, hemagglutinin, two of its subunits, internal m and np proteins of influenza viruses a/fpv/rostock (h7n1), a/pr/8/34 (h1n1) and x-31 (h3n2) were obtained in preparative amounts and characterized by amino acid and n-terminus analyses.19921406760
n-glycans attached to the stem domain of haemagglutinin efficiently regulate influenza a virus replication.the haemagglutinin (ha) protein of fowl plague virus a/fpv/rostock/34 (h7n1) contains three n-linked oligosaccharide side chains in its stem domain. these stem glycans, which are attached to the asn residues at positions 12, 28 and 478, are highly conserved throughout all ha protein sequences analysed to date. in a previous study, in which mutant ha proteins lacking individual stem glycosylation sites had been expressed from an sv-40 vector, it was shown that these glycans maintain the ha protei ...200211842255
presence of avian influenza virus (aiv) subtypes h5n2 and h7n1 in emus (dromaius novaehollandiae) and rheas (rhea americana): virus isolation and serologic findings.avian influenza virus (aiv) subtypes h5n2 and h7n1 were isolated from emus (dromaius novaehollandiae) and rheas (rhea americana) in texas and north carolina. all the rheas and emus had a history of respiratory disease except one emu, which was clinically normal. the isolates were not pathogenic for chickens and turkeys under the conditions of the experiment. humoral antibodies to all known hemagglutinin (h) subtypes except h10, h13, and h14 and to all nine neuraminidase (n) subtypes were found i ...19957794192
characterization of a cold-sensitive (cs) recombinant between two influenza a strains.recombinants between fowl plague virus (fpv, h7n1) and the hong kong (h3n2) or singapore (h2n2) influenza virus strains carrying the hemagglutinin of fpv and the neuraminidase of the human strains form only very tiny plaques at 33 degrees, but normal plaques at 37 degrees. one recombinant (113/ho) has been studied in more detail. it multiplies only very slowly at 33 degrees, the nonpermissive temperature. adsorption and penetration are normal at 33 degrees, but synthesis of protein is impeded. t ...19836636541
susceptibility of pigeons to avian influenza.susceptibility to infection with avian influenza virus (aiv) was studied in pigeons inoculated via oculonasal (experiment 1) or intravenous (experiment 2) route. chickens were included as susceptible hosts in both experiments. two subtypes each of the highly pathogenic aiv (hpaiv; hp ck/pa h5n2 and hp ck/australia h7n7) and non-pathogenic aiv (npaiv; np ck/pa h5n2 and np emu/tx h7n1) at a dose of 10(5) embryo infective dose per bird were used as inoculum. the pigeons inoculated with hp ck/pa h5n ...19968883790
carbohydrates of influenza virus. structural elucidation of the individual glycans of the fpv hemagglutinin by two-dimensional 1h n.m.r. and methylation analysis.the structures of the oligosaccharides of the hemagglutinin of fowl plague virus [influenza a/fpv/rostock/34 (h7n1)] have been elucidated by one- and two-dimensional 1h n.m.r. spectroscopy at 500 mhz and by microscale methylation analysis. n-glycosidic oligosaccharides of the oligomannosidic (om) and of the n-acetyllactosaminic type have been found, the latter type comprising biantennary structures, without (a) or with (e) bisecting n-acetylglucosamine, and triantennary (c) structures. analysis ...19854054103
the specific inhibition of influenza a virus maturation by amantadine: an electron microscopic examination.amantadine specifically inhibits the release of virus particles from cells infected with the rostock (h7n1) strain of influenza a virus, apparently as a consequence of a membrane protein m2-mediated conversion of haemagglutinin (ha) to its low ph conformation. electron microscopic observations, together with immunogold labelling, showed that amantadine action does not alter the distribution of ha on the cell surface nor does it prevent the formation of budding virus particles. it was not possibl ...19911990063
targeted infection of endothelial cells by avian influenza virus a/fpv/rostock/34 (h7n1) in chicken embryos.the tissue tropism and spread of infection of the highly pathogenic avian influenza virus a/fpv/rostock/34 (h7n1) (fpv) were analyzed in 11-day-old chicken embryos. as shown by in situ hybridization, the virus caused generalized infection that was strictly confined to endothelial cells in all organs. studies with reassortants of fpv and the apathogenic avian strain a/chick/germany/n/49 (h10n7) revealed that endotheliotropism was linked to fpv hemagglutinin (ha). to further analyze the factors de ...200010933711
chemical cross-linking of proteins of the influenza virion. 2. acid-induced irreversible conformational changes in ha1 and ha2.purified influenza virus (a/fpv/rostock/34;h7n1) was exposed briefly to ph 5 before returning to an alkaline ph. virus was then reacted with one of three chemical cross-linking reagents [dimethyl suberimidate (dms), tartryl diazide (tda), or formaldehyde which span 11, 6, and 2a, respectively]. cross-linked polypeptides were analysed by sds-polyacrylamide gel electrophoresis under reducing conditions and identified with monospecific antisera against ha1, ha2, np and m1. acidification resulted in ...19892604546
chemical crosslinking of proteins of the influenza virion. 1. interrelationships.purified influenza virus (a/fpv/rostock/34; h7n1) was reacted with one of three chemical crosslinking reagents [dimethylsuberimidate (dms), tartryl diazide (tda) and formaldehyde] under conditions designed to give a ladder of crosslinked polypeptides (putative homo- and heteropolymers) when analysed by sds-polyacrylamide gel electrophoresis under reducing conditions. the different virion polypeptides were identified by western blotting with monospecific antisera against ha1, ha2, np, and m1. whe ...19892604545
avian influenza epidemic in italy due to serovar h7n1.beginning at the end of march 1999, a syndrome characterized by severe depression, anorexia, fever, and respiratory and enteric symptoms appeared in flocks of turkeys and, to a lesser extent, of chickens in the densely populated poultry-rearing regions of northeast italy. the disease was characterized by sinusitis, tracheitis, peritonitis, and pancreatitis. the mortality varied between 5% and 90%. the disease was diagnosed as low pathogenic avian influenza, h7n1 serotype. after a summer period o ...200111332492
inhibition of release of lentivirus particles with incorporated human influenza virus haemagglutinin by binding to sialic acid-containing cellular receptors.mutants of the haemagglutinin (ha) gene of human influenza virus a/aichi/2/68 (h3n2) encoding ha proteins that are proteolytically cleaved intracellularly, defective in binding to cellular receptors or defective for acylation within the cytoplasmic c terminus have been generated. here, the properties of these mutated ha molecules are described and their incorporation into the lipid membrane of released human immunodeficiency virus (hiv)-like particles is analysed. it is demonstrated that, when p ...200111562541
[antiviral activity of 2'-deoxy-2'-fluoroguanosine against influenza and herpes simplex viruses in cultured cells].high antiviral activity of 2'-deoxy-2'fluoroguanosine (2'-d-2'-fg) was observed in chicken embryo cells infected with fpv/rostock/34 (h7n1) influenza virus and herpes simplex virus (hsv) type i (strain 1c). 50% inhibitory concentration (ic50) of 2'-d-2'-fg was 1.44 microm for fpv and 0.093 microm for hsv. ic50 of remantadine hydrochloride, ribavirin (fpv), and acycloguanosine (hsv) were < 0.46, 14.4, and 0.08 microm, respectively. anti-hsv activity was confirmed in vero cells: ic50 < 0.34 microm ...200111715709
clinical, gross, and microscopic findings in different avian species naturally infected during the h7n1 low- and high-pathogenicity avian influenza epidemics in italy during 1999 and 2000.from the end of march to the beginning of december 1999, an epidemic of low-pathogenicity avian influenza (lpai), caused by a h7n1 type a influenza virus, affected the intensively reared poultry population of northeastern italy. a total of 199 flocks were diagnosed with influenza infection. the highest number affected flocks were in meat turkeys (164), with only a limited number of turkey breeder, chicken (breeders, broilers, and table egg layers), and guinea fowl flocks infected. following the ...200314575075
neutralization of influenza virus by low concentrations of hemagglutinin-specific polymeric immunoglobulin a inhibits viral fusion activity, but activation of the ribonucleoprotein is also inhibited.high concentrations of hemagglutinin-specific neutralizing polymeric monoclonal immunoglobulin a (iga) inhibit attachment of the majority of type a influenza virus virions to cell monolayers and tracheal epithelium (h. p. taylor and n. j. dimmock, j. exp. med. 161:198-209, 1985; m. c. outlaw and n. j. dimmock, j. gen. virol. 71:69-76, 1990). a minority of virions attaches but is not infectious. here, we report that a different mechanism operates when influenza virus a/puerto rico/8/34 (h1n1) is ...19921583731
chemical and enzymatic synthesis and antiviral properties of 2'-deoxy-2'-fluoroguanosine.chemical and enzymatic methods were employed for the synthesis of the title compound, 2'f-guo 7. high antiviral activity of 2'f-guo was established in chick embryo cells infected with influenza virus fpv/rostock/34 (h7n1) and herpes simplex virus (hsv) type i (1c strain).199910432666
the 1999-2000 avian influenza (h7n1) epidemic in italy: veterinary and human health implications.from the end of march to the beginning of december 1999, 199 outbreaks of low pathogenicity avian influenza (lpai) were diagnosed in the veneto and lombardia regions, which are located in the northern part of italy. the virus responsible for the epidemic was characterized as a type a influenza virus of the h7n1 subtype of low pathogenicity. on the 17th of december, highly pathogenic avian influenza (hpai) was diagnosed in a meat turkey flock in which 100% mortality was observed in 72 h. the infe ...200212062787
interdependence of hemagglutinin glycosylation and neuraminidase as regulators of influenza virus growth: a study by reverse genetics.the hemagglutinin (ha) of fowl plague virus a/fpv/rostock/34 (h7n1) carries two n-linked oligosaccharides attached to asn123 and asn149 in close vicinity to the receptor-binding pocket. in previous studies in which ha mutants lacking either one (mutants g1 and g2) or both (mutant g1,2) glycosylation sites had been expressed from a simian virus 40 vector, we showed that these glycans regulate receptor binding affinity (m. ohuchi, r. ohuchi, a. feldmann, and h. d. klenk, j. virol. 71:8377-8384, 19 ...200010864641
low-pathogenicity avian influenza (lpai) in italy (2000-01): epidemiology and 1999-2000, italy was affected by the most severe avian influenza (ai) epidemic that has ever occurred in europe. the epidemic was caused by a type a influenza virus of the h7n1 subtype, which originated from the mutation of a low-pathogenicity (lp) ai virus of the same subtype. from august to november 2000, 4 months after the eradication of the highly pathogenic (hp) ai virus, the lpai strain re-emerged and infected 55 poultry farms mainly located in the southern area of verona province (vene ...200314575102
tight binding of influenza virus hemagglutinin to its receptor interferes with fusion pore dilation.deletion of oligosaccharide side chains near the receptor binding site of influenza virus a/ussr/90/77 (h1n1) hemagglutinin (ha) enhanced the binding of ha to erythrocyte receptors, as was also observed with a/fpv/rostock/34 (h7n1). correlated with the enhancement of binding activity, the cell fusion activity of ha was reduced. a mutant ha in which three oligosaccharide side chains were deleted showed the highest level of binding and the lowest level of fusion among the has tested. the cell fusi ...200212438566
standardization of an inactivated h17n1 avian influenza vaccine and efficacy against a/chicken/italy/13474/99 high-pathogenicity virus infection.the minimum requirements for assessing the immunogenicity of an experimental avian influenza (ai) vaccine prepared from inactivated a/turkey/italy/2676/99 (h7n1) low-pathogenicity (lp) ai (lpai) virus were determined in chickens of different ages. a correlation between the amount of hemagglutinin (ha) per dose of vaccine and the protection against clinical signs of disease and infection by a/chicken/italy/13474/99 highly pathogenic (hp) ai (hpai) virus was established. depending on the vaccinati ...200314575107
acylation of the influenza hemagglutinin modulates fusion activity.the influenza virus hemagglutinin (ha) contains three highly conserved cysteine residues at positions 551, 559, and 562 close to the carboxyl-terminus of the ha2 subunit which serve as palmitylation sites. wild-type ha of influenza virus a/fpv/rostock/34 (h7n1) and ha permutated by exchange of the acylated cysteine to serine residues were expressed in cv-1 cells by a sv40 vector system. since density of immunostained ha on the cell surface measured by flow cytometric analysis did not differ betw ...19989721237
avian influenza attributable to serovar h7n1 in light layers in march 1999 a syndrome characterized by depression, anorexia, fever, and respiratory and enteric signs appeared in many flocks of turkeys and, to a lesser extent, chickens in the densely populated poultry-rearing regions of northeastern italy. initially the disease was characterized by sinusitis, tracheitis, peritonitis, and pancreatitis. the responsible agent was identified as low-pathogenicity (lp) avian influenza (ai) of h7n1 subtype. concerning the light layers, the mortality was variable, ...200314575137
strategies to improve protection against low-pathogenicity h7 avian influenza virus infection using dna vaccines.eukaryotic expression plasmids encoding either the avian influenza hemagglutinin or matrix genes (pcmv-ha and pcmv-m, respectively) were constructed. the viral genes were derived from a low-pathogenicity h7n1 strain, a/chicken/italy/1067/99, isolated during the 1999-2001 epizootic in italy. the plasmid was administered to 4-to-5-wk-old specific-pathogen-free chickens by several different injection methods. for the initial studies comparing methods of vaccine injection, results were compared base ...200314575138
influenza virus variants with reduced susceptibility to inhibition by a polyphenol extract from geranium sanguineum l.a polyphenol extract obtained from the bulgarian medicinal plant geranium sanguineum l. (pc) inhibited influenza virus reproduction in vitro, in ovo and in vivo. the inhibitory activity of the plant preparation was proved to be selective and specific. two variants of the virus a/chicken/germany/34, strain rostock (h7n1) (a/rostock) with reduced drug sensitivity were selected by following passages in chicken embryo fibroblast (cef) cells in the presence of inhibitory concentrations of the substan ...200312622254
development and preliminary validation of an ad hoc n1-n3 discriminatory test for the control of avian influenza in italy.the development of a discriminatory test, based on the differentiation between n1 and n3 antibodies, to be used in the framework of a vaccination program, based on vaccination with a heterologous h7n3 inactivated vaccine against the italian h7n1 field virus, is reported. the indirect immunofluorescence antibody (iifa) assay was based on the expression of the n1 protein in a baculovirus system. highfive insect cells were transfected with the recombinant virus and used as an antigen in the iifa te ...200314575111
n1 neuraminidase of influenza virus a/fpv/rostock/34 has haemadsorbing activity.the neuraminidase (na) gene of influenza virus a/fpv/rostock/34 virus (h7n1) was cloned and expressed in sf9 cells using a baculovirus vector. the expression product had the expected molecular mass and showed neuraminidase activity. na expressed in sf9 cells also showed haemagglutinating activity as indicated by its ability to induce haemadsorption of chicken red blood cells. haemadsorption depended on the presence of neuraminic acid on the erythrocytes, but was not blocked by 2-deoxy-2,3-dehydr ...19959049377
igg neutralization of type a influenza viruses and the inhibition of the endosomal fusion stage of the infectious pathway in bhk cells.we have used three strains of type a influenza virus (a/fowl plaque virus/rostock/34: h7n1; a/pr/8/34: h1n1; a/x31: h3n2) labeled with the fluorescent probe octadecyl rhodamine b chloride (r18) to study how neutralizing monoclonal igg, specific for the haemagglutinin, affects the interaction of virus with bhk-21 cells. r18 labels viral lipid and self-quenches in the virion; dilution of r18 by fusion of viral and cellular membranes or by dissolution in detergent activates fluorescence. igg neutra ...19938337821
report on avian influenza in the eastern hemisphere during 1997-2002.since the fourth international symposium on avian influenza (ai) there has been considerable ai activity in the eastern hemisphere. the higher profile of ai resulting from the human infections with h5n1 and h9n2 viruses in hong kong, in 1997 and 1999, respectively, resulted in increased reporting and active surveillance. there have been three reported incidents of high-pathogenicity (hp) ai: h5n2 in northeastern italy in 1997 (eight outbreaks); h5n1 in hong kong in 1997 recurring in 2001 and 200 ...200314575066
changes in the haemagglutinin and the neuraminidase genes prior to the emergence of highly pathogenic h7n1 avian influenza viruses in italy.outbreaks of avian influenza due to an h7n1 virus of low pathogenicity occurred in domestic poultry in northern italy from march 1999 until december 1999 when a highly pathogenic avian influenza (hpai) virus emerged. nucleotide sequences were determined for the ha1 and the stalk region of the neuraminidase (na) for viruses from the outbreaks. the hpai viruses have an unusual multibasic haemagglutinin (ha) cleavage site motif, peipkgsrvrrglf. phylogenetic analysis showed that the hpai viruses aro ...200111448033
avian influenza in italy 1997-2001.from 1997 to 2001, italy has been affected by two epidemics of high-pathogenicity avian influenza. the first epidemic was caused by a virus of the h5n2 subtype and was limited to eight premises in backyard and semi-intensive flocks. the prompt identification of the disease was followed by the implementation of european union (eu) directive 92/40/eec and resulted in the eradication of infection without serious consequences to the poultry industry. the 1999-00 epidemic was caused by a virus of the ...200314575074
field experiences in the control of avian influenza outbreaks in densely populated poultry areas.from 1997 to 2003, italy has been affected by two epidemics of highly pathogenic avian influenza (hpai) and by several outbreaks of low pathogenic avian influenza (lpai). in 1999-2000 a severe hpai epidemic affected the country, causing 413 outbreaks: a total of about 16 million birds died or were stamped out. from august 2000 to march 2001, a h7n1 lpai strain infected 78 poultry farms. the last affected flock was stamped out on the 26th of march 2001. in october 2002, another lpai virus of the ...200415742627
detection of influenza a virus by rt-pcr and standard methods in experimental infection of ducks.cloacal swabs collected from mallard ducks (anas platyrhynchos) experimentally infected with a h7n1 avian influenza strain were examined by reverse transcription polymerase chain reaction to detect the influenza a virus. reverse transcription polymerase chain reaction was compared with standard methods: inoculation of embryonated chicken eggs and inoculation of three established cell lines: newborn swine kidney cells, newborn pig trachea cells and madine darby canine kidney cells. reverse transc ...200515782624
in vitro anti-influenza virus activity of the pavine alkaloid (-)-thalimonine isolated from thalictrum simplex l.the pavine alkaloid (-)-thalimonine (thl), isolated from the mongolian plant thalictrum simplex inhibited markedly the reproduction of influenza virus a/germany/27, str. weybridge (h7n7) and a/germany/34, str. rostock (h7n1) in cell cultures of chicken embryo fibroblasts. in a number of assays at a non-toxic concentration range of 0.1-6.4 microm the alkaloid inhibited viral reproduction in a selective and specific way (selectivity index = 640, 106.6, respectively). expression of viral glycoprote ...200312856918
analysis of the 1999-2000 highly pathogenic avian influenza (h7n1) epidemic in the main poultry-production area in northern italy.we evaluated the effects of risk factors and control policies following the highly pathogenic avian influenza (hpai) epidemic that struck northern italy's poultry industry in the winter of 1999-2000. the epidemic was caused by a type-a influenza virus of the h7n1 subtype, that originated from a low-pathogenic ai virus which spread among poultry farms in northeastern italy in 1999 and eventually became virulent by mutation. most infected premises (ip) were located in the regions of lombardy and v ...200616243405
disifin (sodium tosylchloramide) and toll-like receptors (tlrs): evolving importance in health and diseases.disifin has emerged as a unique and very effective agent used in disinfection of wounds, disinfection of surfaces, materials and water, and other substances contaminated with almost every type of pathogenic microorganism ranging from viruses, bacteria, fungi and yeast, and, very possibly, protozoan parasites, as well. the major active component of disifin is tosylchloramide sodium (chloramine t). however, the mechanism by which disifin suppresses the activities of pathogenic microbial agents rem ...200717876621
protection of chickens against highly lethal h5n1 and h7n1 avian influenza viruses with a recombinant fowlpox virus co-expressing h5 haemagglutinin and n1 neuraminidase genes.inactivated whole avian influenza virus (aiv) vaccine provides protection against homologous haemagglutinin (ha) subtype virus, but poor protection against a heterologous ha virus. moreover, it induces chickens to produce antibodies to cross-reactive antigens, especially nucleoprotein, which is limits aiv serological surveillance. in this study, a recombinant fowlpox virus co-expressing ha (h5 subtype) and na (ni subtype)genes of aiv was evaluated for its ability to protect chickens against intr ...200312745375
development of a diva (differentiating infected from vaccinated animals) strategy using a vaccine containing a heterologous neuraminidase for the control of avian influenza.the present paper reports of the development and validation of a control strategy for avian influenza infections in poultry. the "diva" (differentiating infected from vaccinated animals) strategy is based on the use of an inactivated oil emulsion vaccine containing the same haemagglutinin (h) subtype as the challenge virus, but a different neuraminidase (n). the possibility of using the heterologous n subtype, to differentiate between vaccinated and naturally infected birds, was investigated thr ...200312745380
serological analysis of serum samples from humans exposed to avian h7 influenza viruses in italy between 1999 and 2003.we evaluated the potential for avian-to-human transmission of low pathogenic avian influenza (lpai) and highly pathogenic avian influenza (hpai) h7n1 and lpai h7n3 viruses that were responsible for several outbreaks of influenza in poultry in italy between 1999 and 2003. a serological survey of poultry workers was conducted by use of a combination of methods. evidence of anti-h7 antibodies was observed in 3.8% of serum samples collected from poultry workers during the period in 2003 when lpai h7 ...200516170747
[genetic characterization of an avian influenza a (h5n1) virus isolated from a sick goose in china].genetic analysis of viral ha gene showed that there were 22 nucleotide differences in ha gene between goose and human h5n1 viruses. the sequence analysis of amino acid on viral protein molecules indicated that there were 7 and 9 position differences between goose and human, chicken h5n1 viruses, respectively. all the three viruses share multiple basic amino acids (r-e-r-r-r-k-k-r) at the cleavage site between ha1 and ha2 domain, that is associated with highly pathogenic h5 avian viruses. except ...199812526344
vaccination policy applied for the control of avian influenza in italy.this paper describes the measures applied to control the re-emergence of the low pathogenicity avian influenza virus of the h7n1 subtype which followed the devastating hpai epidemic in italy between 1999 and 2000. to control the lpai virus and to develop a novel control strategy, a "diva" (differentiating infected from vaccinated animals) strategy was developed and combined to a strict territorial control programme. the "diva" strategy was based on the use of an inactivated oil emulsion vaccine ...200314677691
experimental challenge model with low pathogenic h7n1 avian influenza virus to assess protection against infection by these viruses. 200314965143
increased resistance of vaccinated turkeys to experimental infection with an h7n3 low-pathogenicity avian influenza virus.a trial was performed to establish whether turkeys vaccinated against avian influenza with a vaccine containing a strain with a heterologous neuraminidase to the challenge virus required a higher infectious dose to develop infection than naïve birds. birds were vaccinated with a commercially available, inactivated oil emulsion product containing the strain a/ty/italy/99/(h7n1) and challenged with different dilutions of a lpai isolate a/ty/italy/8000/02(h7n3) obtained during the 2002 to 2003 ital ...200415276982
quantification of the effect of vaccination on transmission of avian influenza (h7n7) in chickens.recent outbreaks of highly pathogenic avian influenza (hpai) viruses in poultry and their threatening zoonotic consequences emphasize the need for effective control measures. although vaccination of poultry against avian influenza provides a potentially attractive control measure, little is known about the effect of vaccination on epidemiologically relevant parameters, such as transmissibility and the infectious period. we used transmission experiments to study the effect of vaccination on the t ...200516330777
ecology and epidemiology of avian influenza in ostriches.avian influenza is important because of its potential devastating effect on poultry health and trade. the ostrich industry of south africa has not escaped the consequences of control and export restrictions resulting from notifiable virus infections. ostrich farmers first observed a syndrome of green urine in the early and mid 1980s. an h7n1 subtype, causing high mortality in young ostriches but with a low pathogenicity index for chickens, was first isolated in 1991. the first highly pathogenic ...200616447494
a retrospective description of a highly pathogenic avian influenza a virus (h7n1/carduelis/germany/72) in a free-living siskin (carduelis spinus linnaeus, 1758) and its accidental transmission to yellow canaries (serinus canaria linnaeus, 1758).a haemagglutinating virus was isolated in summer 1972 from a single free-living siskin (carduelis spinus linnaeus, 1758) in embryonated chicken eggs. additional cases of morbidity or mortality were not observed in the area were the sick siskin was found. the virus was characterized as an avian influenza a virus of the subtype h7n1 and designated h7n1/carduelis/germany/72. the virus induced following experimental inoculation of chicken embryos a high rate mortality (mean death time approximately ...200515714871
control of avian influenza in italy: from stamping out to emergency and prophylactic vaccination.since 1997, north-eastern italy has been repeatedly challenged by avian influenza (ai) infections caused by viruses of the h5 and h7 subtypes. the penetration of such infections in the industrial circuit in densely populated poultry areas (dppas) resulted in massive spread, and early attempts to control ai only by stamping-out and restriction policies resulted in death or culling of millions of birds. the re-emergence or the introduction of ai viruses in the same dppa resulted in the development ...200616447501
h5n1 chicken influenza viruses display a high binding affinity for neu5acalpha2-3galbeta1-4(6-hso3)glcnac-containing characterize differences in the receptor-binding specificity of h5n1 chicken viruses and viruses of aquatic birds, we used a panel of synthetic polyacrylamide (paa)-based sialylglycopolymers that carried identical terminal neu5acalpha2-3gal fragments but varied by the structure of the next saccharide residues. a majority of duck viruses irrespective of their ha subtype, bound with the highest affinity to trisaccharide neu5acalpha2-3galbeta1-3glcnac, suggesting that these viruses preferentiall ...200415302215
molecular characterization of low pathogenicity h7n3 avian influenza viruses isolated in italy.the complete coding regions of the surface glycoproteins, nucleoprotein (np), polymerase 2 (pb2), and matrix (m) of a/turkey/214845/02 and a/turkey/220158/99 (h7n3) low pathogenicity avian influenza (lpai) viruses isolated in october 2002 in italy were amplified and sequenced to determine the epidemiologic relationships with an a/turkey/italy/4603/99 (h7n1/4603/99) lpai virus isolated during the 1999-2001 epizootic in italy. the hemagglutinin (ha) of h7n3 viruses showed 97.8% nucleotide similari ...200415283425
origin of highly pathogenic h5n1 avian influenza virus in china and genetic characterization of donor and recipient viruses.genetic analysis of all eight genes of two nanchang avian influenza viruses, a/duck/nanchang/1681/92 (h3n8-1681) and a/duck/nanchang/1904/92 (h7n1-1904), isolated from jiangxi province, china, in 1992, showed that six internal genes of h3n8-1681 virus and five internal (except ns gene) genes of h7n1-1904 virus were closely similar to a/goose/guangdong/1/96 (h5n1) virus, the first highly pathogenic avian influenza (hpai) virus of subtype h5n1 isolated in asia. the neuraminidase (na) gene of gs/gd ...200717947535
development of an antigen-capture elisa for detection of h7 subtype avian influenza from experimentally infected chickens.emergence of highly pathogenic avian influenza h7n1 was due to mutation of low pathogenic avian influenza h7n1 strain, which caused outbreaks in italy between 1999 and 2000, and resulted in complete mortality of infected poultry. this outbreak places increased importance on the early detection of h7n1 aiv. here we describe the development of a detection method for h7n1 virus from infected chickens using a specific antigen-capture-elisa (ac-elisa). a panel of mabs was developed against the surfac ...200817950911
development of vaccine strains of h5 and h7 influenza establish vaccine strains of h5 and h7 influenza viruses, a/duck/hokkaido/vac-1/04 (h5n1) [vac-1/04 (h5n1)], a/duck/hokkaido/vac-3/07 (h5n1) [vac-3/07 (h5n1)], and a/duck/hokkaido/ vac-2/04 (h7n7) [vac-2/04 (h7n7)] were generated from non-pathogenic avian influenza viruses isolated from migratory ducks. vac-1/04 (h5n1) and vac-3/07 (h5n1) were generated by genetic reassortment between h5n2 or h5n3 virus as an ha gene provider and h7n1 or h6n1 viruses as an na gene provider. vac-2/04 (h7n7) wa ...200818318111
a vaccine prepared from a non-pathogenic h7n7 virus isolated from natural reservoir conferred protective immunity against the challenge with lethal dose of highly pathogenic avian influenza virus in chickens.during 2001-2004, 41 h7 influenza viruses (2 h7n1 and 39 h7n7 strains) were isolated from fecal samples of migratory ducks that flew from siberia in the autumn of each year to japan and mongolia. a phylogenetic analysis of the hemagglutinin (ha) genes of the nine representative isolates revealed that they belonged to the eurasian lineage and the deduced amino acid sequence at the cleavage site of the has represented apathogenic profiles. one of the h7 isolates a/duck/mongolia/736/02 (h7n7) was c ...200818346824
progressive truncation of the non-structural 1 gene of h7n1 avian influenza viruses following extensive circulation in order to support eradication efforts of avian influenza (ai) infections in poultry, the implementation of "diva" vaccination strategies, enabling the differentiation of infected from vaccinated animals have been recommended by international organisations. a system, based on the detection of antibodies to the non-structural 1 (ns1) protein of ai has been proposed but the success of such a system lies in the conservation of the ns1 protein among different ai isolates. with this in mind, the ns1 ...200616464514
avian influenza a viruses in birds of the order psittaciformes: reports on virus isolations, transmission experiments and vaccinations and initial studies on innocuity and efficacy of oseltamivir in ovo.birds of the order psittaciformes are - besides chickens, turkeys and other birds - also susceptible to infection with avian influenza a viruses (aiv) and succumb following severe disease within one week. published data prove that various parakeets, amazons, cockatoos, african grey parrots and budgerigars (genera barnardius, psittacula, cacatua, eolophus, amazona, myiopsitta, psittacus and melopsittacus) were found dead following natural infections. natural infections of highly pathogenic avian ...200717724934
conventional inactivated bivalent h5/h7 vaccine prevents viral localization in muscles of turkeys infected experimentally with low pathogenic avian influenza and highly pathogenic avian influenza h7n1 isolates.highly pathogenic avian influenza (hpai) viruses cause viraemia and systemic infections with virus replication in internal organs and muscles; in contrast, low pathogenicity avian influenza (lpai) viruses produce mild infections with low mortality rates and local virus replication. there is little available information on the ability of lpai viruses to cause viraemia or on the presence of avian influenza viruses in general in the muscles of infected turkeys. the aim of the present study was to d ...200818622857
characterization of an avian influenza virus of subtype h7n2 isolated from chickens in northern h7n2 avian influenza virus was isolated from chickens during routine surveillance in northern china in 2002. to understand the origin of this virus, we completely sequenced its genome. the pb1, pa, ha, and m genes of this virus were highly homologous with those of the wild bird virus a/africa starling/eng-q/983/79 (h7n1). the np and ns genes were closely related to those of two other wild bird viruses isolated 30 years ago. the closest relatives of the pb2 and na genes of the virus were those ...200616791426
importance of a prime-boost dna/protein vaccination to protect chickens against low-pathogenic h7 avian influenza infection.control of h5/h7 low-pathogenic avian influenza (lpai) virus circulation is a major issue regarding animal and public health consequences. to improve vaccines and to prevent vaccinated poultry from becoming infected and from shedding wild viruses, we initiated studies targeting prevention of h7 infection through dna vaccines encoding h7 and m1 viral proteins from an italian h7n1 lpai virus isolated from poultry in 1999. more recently, we expressed recombinant h7 and m1 proteins in the baculoviru ...200717494616
efficacy of inactivated vaccines against h5n1 avian influenza infection in ducks.the current asian h5n1 highly pathogenic avian influenza virus has spread over much of asia and into europe and africa. as well as affecting village and commercial chicken operations in many south east asian countries, it differs from past h5 avian influenza viruses in that it causes morbidity and mortalities in other domesticated birds, such as ducks and turkeys and in wild water birds. effective vaccines that can prevent infection, as well as disease, and be used in a variety of avian species ...200717028058
development and use of fowlpox vectored vaccines for avian influenza.the avian influenza (ai) vaccine designated trovac-aiv h5 (trovac-h5) contains a live recombinant fowlpox rec. (fp) recombinant (recfp), expressing the hemagglutinin (ha) gene of an ai h5 subtype isolate. this recombinant vaccine was granted a license in the united states for emergency use in 1998 and full registration in mexico, guatemala, and el salvador where over 2 billion doses have been administered. one injection of trovac-h5 protects chickens against ai-induced mortality and morbidity fo ...200617135511
evaluation of chicken-origin (df-1) and quail-origin (qt-6) fibroblast cell lines for replication of avian influenza viruses.avian influenza viruses (aivs) are isolated routinely and propagated in specific pathogen free embryonated chicken eggs (ece) and mammalian origin madin-darby canine kidney (mdck) cell line. continuous avian cell lines offer advantages for propagation of aivs over mdck cells because they maintain species specificity, and lower recurring costs compared to ece. in this study, the characteristics of two avian fibroblast cell lines were evaluated, df-1 (chicken-origin) and qt-6 (quail-origin), and t ...200818638503
detection of influenza a type-specific antibodies in chicken and turkey sera by enzyme linked immunosorbent elisa test for detection of influenza a virus type-specific antibodies in chicken and turkey sera is described. antigen was prepared from infected allantoic fluids using an h7n1 virus. virus particles were disrupted using sodium deoxycholate to release internal antigens and tests were standardised by testing batches of sera from influenza-free birds. a negative antigen was included in the test and was shown to be effective in eliminating the non-specific increase in absorbance values observed ...198918679876
influenza virus circulation in wild aquatic birds in italy during h5n2 and h7n1 poultry epidemic periods (1998 to 2000).two epidemics of avian influenza due to h5 and h7 highly pathogenic viruses occurred in poultry in italy in 1997/98 and 1999/2000, respectively. the circulation of these serotypes in wild aquatic birds was investigated examining 638 cloacal swabs and 621 sera collected from 150 gulls, 162 coots, and 326 ducks trapped in italian wetlands from 1998 to 2000. seroprevalences against influenza a viruses, detected by a double-antibody sandwich-blocking enzyme-linked immunosorbent assay (elisa), were 1 ...200516537162
proteinase inhibitors from streptomyces with antiviral extensive screening study for the production of proteolytic inhibitors has been carried out on 75 streptomyces strains. it was found that 18 of the strains and/or their variants (24%) produced proteinaceous substances, which belonged to the group of typical serine protease inhibitors. 23 samples were tested for inhibitory activity on the replication of influenza virus a/germany/34, strain rostock (h7n1) (a/rostock) in chicken embryonic fibroblast (cef) cells. eleven of the tested samples (52. ...200617139614
transmission parameters of highly pathogenic avian influenza (h7n1) among industrial poultry farms in northern italy in 1999-2000.we estimated between-farm transmission parameters of the highly pathogenic avian-influenza (hpai) epidemic that struck the poultry industry of northern italy (including turkeys, layer hens, broilers, gamebirds, and waterfowl) from december 1999 through april 2000. we estimated the average number of susceptible farms that were infected with hpai virus by each infectious farm during a day (beta) with a generalised linear model (glm). the hpai's reproductive ratios (r(h); the average number of new ...200717531332
the use of vaccination to combat multiple introductions of notifiable avian influenza viruses of the h5 and h7 subtypes between 2000 and 2006 in italy.since 1999, italy has been challenged by several epidemics of notifiable avian influenza (nai) of the h5 and h7 subtypes, occurring in the densely populated poultry areas of northern part of the country. vaccination with a conventional vaccine containing a seed strain with a different neuraminidase subtype to the field virus was used to complement biosecurity and restriction measures as part of an overall eradication strategy. this vaccination technique, known as the "diva-differentiating infect ...200717418460
virologic findings in selected free-range mule duck farms at high risk for avian influenza infection.prevalence of avian influenza infection in free-range mule ducks (a cross between muscovy [cairina moschata domesticus] and pekin ducks [anas platyrhychos domesticus]) is a matter of concern and deserves particular attention. thus, cloacal swabs were collected blindly from 30 targeted mule flocks at 4, 8, and 12 wk of age between october 2004 and january 2005. they were stored until selection. on the basis of a positive h5 antibody detection at 12 wk of age with the use of four h5 antigens, the ...200717494595
spatial analysis of the 1999-2000 highly pathogenic avian influenza (h7n1) epidemic in northern italy.the effect of proximity on infected premises was evaluated during the highly pathogenic avian influenza (hpai) epidemic that struck northern italy in 1999-2000 by quantifying the spatial and temporal clustering of cases. the epidemic was caused by an h7n1 subtype of type a influenza virus that originated from a low-pathogenic ai virus that spread among poultry farms in northeastern italy in 1999 and eventually became virulent by mutation. more than 90% of 413 infected premises were located in lo ...200717494598
induction of neutralising antibodies by virus-like particles harbouring surface proteins from highly pathogenic h5n1 and h7n1 influenza viruses.there is an urgent need to develop novel approaches to vaccination against the emerging, highly pathogenic avian influenza viruses. here, we engineered influenza viral-like particles (flu-vlps) derived from retroviral core particles that mimic the properties of the viral surface of two highly pathogenic influenza viruses of either h7n1 or h5n1 antigenic subtype. we demonstrate that, upon recovery of viral rnas from a field strain, one can easily generate expression vectors that encode the ha, na ...200616948862
antigenic and genetic analysis of h5 influenza viruses isolated from water birds for the purpose of vaccine order to prepare h5n1 influenza virus vaccine, the hemagglutinins (has) of 14 h5 virus isolates from water birds in asia were antigenically and genetically analyzed. phylogenetic analysis of the h5 ha genes revealed that 13 isolates belong to eurasian and the other one to north american lineages. each of the deduced amino acid sequences of the has indicated a non-pathogenic profile. antigenic analysis using a panel of monoclonal antibodies recognizing six different epitopes on the ha of a/duc ...200818932020
[site-directed modification of caspase cleavage site regions in avian influenza virus proteins].a reverse genetics approach was applied to generate variants of avian influenza virus a/fpv/ro/34 (h7n1) containing mutations in the caspase cleavage sites of np and m2 proteins. mutation gly16 --> asp in avian virus np made this protein (npgd) sensitive to caspases, like human virus np, and permitted its cleavage in infected cells. mutant recombinant virus npgd was able to replicate and stably carried gly --> asp mutation during passages in cultured cells, chicken eggs, and chickens. this varia ...200819172901
h7n1 avian influenza in italy (1999 to 2000) in intensively reared chickens and turkeys.from the end of march to the beginning of december 1999, an epidemic of low pathogenicity avian influenza (lpai) affected the industrial poultry population of northern italy. the virus responsible for the epidemic was subtyped as h7n1 with an intravenous pathogenicity index (ivpi) of 0.0, and a deduced amino acid sequence of the region coding for the cleavage site of the haemagglutinin molecule typical of low pathogenicity viruses. the circulation of the virus in a susceptible population for sev ...200019184849
highly pathogenic avian influenza (h7n1) in ostriches (struthio camelus).the clinical, virological and pathological findings observed in a natural outbreak of highly pathogenic avian influenza in intensively farmed ostriches (struthio camelus) are reported. clinical signs characterized by anorexia, depression, nervous and enteric signs were observed in young birds, which resulted in death of 30% of the affected birds. virus isolation performed in accordance with the guidelines listed in european union directive 92/40/eec yielded an influenza a virus of the h7n1 subty ...200019184863
mortality in muscovy ducks (cairina moschata) and domestic geese (anser anser var. domestica) associated with natural infection with a highly pathogenic avian influenza virus of h7n1 subtype.among the 413 outbreaks of highly pathogenic avian influenza (hpai) caused by a virus of the h7n1 subtype, which occurred in italy during 1999 and 2000, an outbreak diagnosed in a backyard flock was characterized by mortality and nervous signs in ducks and geese. dead geese (anser anser var. domestica) and muscovy ducks (cairina moschata) were submitted to the laboratory for bacteriological, virological, histological and immunohistochemical investigations. routine bacteriological tests resulted ...200119184894
risk factors for highly pathogenic h7n1 avian influenza virus infection in poultry during the 1999-2000 epidemic in 1999-2000, italian poultry production was disrupted by an h7n1 virus subtype epidemic of highly pathogenic avian influenza (hpai). the objectives of the present study were to identify risk factors for infection on poultry farms located in regions that had the highest number of outbreaks (veneto and lombardia) and the impact of pre-emptive culling as a complementary measure for eradicating infection. a cox regression model that included spatial factors, such as the g index, was used. the resul ...200918684649
a recombinant vesicular stomatitis virus replicon vaccine protects chickens from highly pathogenic avian influenza virus (h7n1).highly pathogenic avian influenza viruses (hpaiv) of subtypes h5 and h7 cause fatal disease in poultry (fowl plague) but also have zoonotic potential. currently commercially available vaccines often do not provide sufficient protection and do not allow easy discrimination between vaccinated and infected birds. therefore, vaccination of domestic poultry against h5 and h7 hpaiv is not allowed in many countries, or is only possible after special permission has been provided. we generated a recombin ...200919135116
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