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genetic drift of equine 2 influenza a virus (h3n8), 1963-1988: analysis by oligonucleotide mapping.comparative analysis by rna oligonucleotide fingerprints of total genomic rna as well as the individual rna segments of equine 2 influenza a virus strains from 1963, 1968, 1979, 1984, 1987 and 1988 revealed genetic diversity. strains from the epizootic outbreak during 1978-1979 showed minor differences among their genomes. the swedish isolates from 1979 up to 1988 showed increasing genomic heterogeneity indicating genetic drift.19902353444
production of monoclonal antibodies against equine influenza: application to a comparative study of various strains of the virus.monoclonal antibodies (mo abs) were prepared against influenza/a/equine/prague/1/56 (h7n7) and influenza/a/equine/miami/1/63 (h3n8) reference strains of equine influenza virus. these monoclonals were tested against the 2 reference strains, 8 field strains of equine influenza virus, 3 human influenza viruses possessing the h3 hemagglutinin, and one virus of human origin possessing the h1 hemagglutinin. two antibodies were obtained in one fusion against the prague/1/56 strain and reacted only with ...19892817730
amino acid sequences of haemagglutinins of influenza viruses of the h3 subtype isolated from horses.the amino acid sequence of the haemagglutinin of a/equine/miami/63 (h3n8), the prototype influenza virus of the h3 subtype from horses, is deduced from the nucleotide sequence of virus rna and compared with the sequences of haemagglutinins of viruses of this subtype isolated from humans [x-31 (h3n2)] and from birds [a/duck/ukraine/63 (h3n8)] and with the sequence of the haemagglutinin of a/equine/fontainebleau/79 (h3n8) a virus isolated from a recent outbreak of equine influenza. the amino acid ...19853973560
isolation of influenza a viruses from migratory waterfowls in san-in district, western japan in winters of 1980-1982.in the two winters of 1980-1982, we surveyed migratory waterfowl of some species staying in san-in district, western japan for influenza virus at a few stations. from november 1980 to april 1981, only two strains of influenza virus, h13n1 and h11n6 subtypes, were isolated from 465 fecal samples from pintails but none from 255 samples from whistling swans nor from 625 black-tailed gulls. from november 1981 to march 1982, 17 viruses were isolated from 1156 fecal samples. fourteen viruses, 10 h7n3, ...19873673333
[properties of reassortants of human and avian influenza viruses. reproduction in mdck cells at suboptimum temperatures].a series of reassortants has been constructed by crossing of uv-inactivated avian influenza virus of h3n8 subtype and live human influenza virus of h1n1 subtype, adapted to growth in continuous canine kidney cell line (mdck). the analysis of rna duplexes has shown that the reassortants contain ha gene of avian influenza virus whereas the other genes belong to human parent virus. the reassortants were efficiently reproduced in mdck cells at low temperature (limiting for the avian parent virus). t ...19883405232
difference in growth behavior of human, swine, equine, and avian influenza viruses at a high temperature.growth characteristics of a wide range of influenza a viruses from different mammals and bird species were examined in an established line of canine kidney (mdck) cells at an ordinary (37 degrees c) and a high temperature (42 degrees c). although all viruses employed in the present study possessed a capability of replicating at 37 degrees c, virus growth at 42 degrees c showed considerable variation and reflected differences in the natural hosts of the isolates. all reference strains and isolate ...19883401117
influenza virus iscoms: antibody response in animals.a monovalent experimental iscom vaccine has been prepared with the envelope glycoproteins haemagglutinin and neuraminidase of the equine virus strain a/solvalla/79 (h3n8). in vaccination trials on balb/c mice the iscom vaccine induced more than ten times higher serum antibody titres measured in elisa than a corresponding experimental micelle vaccine. similarly, in guinea-pigs the iscoms induced about tenfold higher haemagglutination inhibition (hi) and neuraminidase inhibition (ni) titres than a ...19883354258
comparison of the virologic and immunologic responses of volunteers to live avian-human influenza a h3n2 reassortant virus vaccines derived from two different avian influenza virus donors.we compared the abilities of the six internal rna segments of two avian influenza viruses, a/mallard/alberta/88/76 (h3n8) and a/mallard/ny/6750/78 (h2n2), to confer attenuation on wild-type human influenza a/bethesda/1/85 (h3n2) virus in seronegative adult volunteers. live avian-human influenza a reassortant virus vaccines derived from either avian virus parent were comparable in the following properties: safety, infectivity, immunogenicity, and genetic stability. since the avian influenza a/mal ...19892913033
development of an enzyme-linked immunosorbent assay (elisa) for the detection of specific antibodies against an h7n7 and an h3n8 equine influenza virus.this paper describes a solid-phase microtitre plate enzyme-linked immunosorbent assay (elisa) for the detection of antibodies to equine influenza viruses. using egg-grown influenza viruses as the antigens attached to the solid phase, cross-reactions were observed between an h7n7 equine virus (designated a1) and an h3n8 equine influenza virus (designated a2) when untreated antisera were tested. absorption of antisera with egg-grown a/porcine/shope/1/33 influenza virus eliminated cross-reactive an ...19846512260
detection of influenza nucleoprotein antigen in nasal secretions from horses infected with a/equine influenza (h3n8) viruses.an antigen capture indirect enzyme linked immunosorbent assay (elisa) was developed to detect influenza nucleoprotein antigen in nasal secretions from horses infected with a/equine/h3n8 viruses. results from this assay were compared with conventional virus isolation in embryonated hens eggs.19882840448
protection against experimental infection with influenza virus a/equine/miami/63 (h3n8) provided by inactivated whole virus vaccines containing homologous virus.thirty-one ponies immunized with inactivated virus vaccine containing a/equine/miami/63 (h3n8) virus and six seronegative ponies were experimentally challenged with the homologous virus strain. all 6 unvaccinated ponies and 11 out of 31 vaccinated ponies became infected. a clear relationship between pre-challenge antibody, measured by single radial haemolysis (srh), and protection was demonstrated as judged by virus excretion, febrile responses and antibody responses. those ponies with srh antib ...19882837409
duration of circulating antibody and immunity following infection with equine influenza virus.the duration of immunity as measured by virological, serological and clinical responses following infection with influenza a/equine/newmarket/79 (h3n8) was assessed in repeated challenge experiments in which ponies were infected by exposure to aerosols of infectious virus. previous infection stimulated complete clinical protection which persisted for at least 32 weeks as demonstrated by the absence of febrile responses and coughing in two groups of ponies infected 16 weeks or 32 weeks after the ...19882835850
cell mediated immune responses in ponies following infection with equine influenza virus (h3n8): the influence of induction culture conditions on the properties of cytotoxic effector cells.cytotoxic cell precursors and/or cytotoxic memory cells were demonstrated in the peripheral blood of ponies after aerosol infection with influenza a/equine/newmarket/79 (h3n8). in order to reveal their cytotoxic potential, peripheral blood mononuclear cells required a secondary antigenic stimulation. in vitro induced cytotoxic cells showed activity against influenza infected target cells in a 3-4 h 51cr-release assay. the reactivity of cytotoxic cells was markedly influenced by the conditions of ...19892552651
isolation of a/equi-2 virus during 1987 equine influenza epidemic in india.processing of nasal materials from clinical cases during the 1987 influenza epidemic in northern and central india resulted in the isolation of two haemagglutinating agents; one each from donkeys and horses at bhiwani in haryana state and ludhiana in punjab state, respectively. these were typed as influenza a/equi-2 viruses by haemagglutination inhibition test. the two isolates were designated as a/equi-2/bhiwani/1/87 and a/equi-2/ludhiana/1/87. the bhiwani/87 isolate was confirmed to have h3n8 ...19892550218
origin of the hemagglutinin on a/equine/johannesburg/86 (h3n8): the first known equine influenza outbreak in south africa.a severe influenza outbreak occurred in horses in south africa in 1986. the causative agent was identified as an influenza virus [a/equine/johannesburg/86 (h3n8)]. antigenic analyses of the hemagglutinin (ha) with ferret antisera and monoclonal antibodies showed that the eq/johannesburg/86 virus is similar to recent equine h3 viruses. the nucleotide sequence analysis on the ha genes of eq/johannesburg/86 and other equine h3 influenza viruses, together with the epidemiological data, clearly demon ...19892548457
antibody isotype responses in the serum and respiratory tract to primary and secondary infections with equine influenza virus (h3n8).serum antibody (iggab, igm and iga) responses to primary and secondary infection with influenza a/equine/newmarket/79 (h3n8) by nebulised aerosol were compared with local (nasopharyngeal and tracheal) antibody responses in ponies. circulating iggab antibody was of long duration after primary infection, whereas igm responses were short-lived after both primary and secondary infections. the antigenic stimulation of secondary infection with equine influenza was sufficient to induce elevations of se ...19892546319
antigenic and genetic conservation of h3 influenza virus in wild ducks.the hemagglutinins of h3 influenza viruses isolated from migratory ducks on the pacific flyway in japan during the period 1977 to 1985 were analyzed antigenically and genetically. antigenic analysis using monoclonal antibodies to the hemagglutinins of a/aichi/2/68 (h3n2) and a/duck/hokkaido/8/80 (h3n8) viruses showed that antigenic drift occurred extensively in human strains, whereas the hemagglutinins of duck viruses were highly conserved. it was also found that the hemagglutinins of duck virus ...19872440178
palmitoylation of the influenza a virus m2 protein.the m2 proteins of a variety of influenza a viruses of different subtypes were shown to possess associated palmitate. susceptibility to removal by reduction or treatment with hydroxylamine is consistent with attachment via a thioester linkage to cysteine. the absence of the acyl group from the m2 proteins of several equine viruses of the h3n8 subtype correlates with the replacement of cysteine 50 with phenylalanine and points to this as the site of palmitate attachment.19902219738
rapid diagnosis of equine influenza.during an epizootic of equine influenza in norway caused by influenza a/equine (h3n8) virus the efficacy of rapid virus diagnosis by the indirect immunofluorescence technique was evaluated. the antiserum used in the test was a polyclonal influenza a virus antiserum with reactivity directed mainly against the common nucleoprotein and matrix protein. this antiserum possessed sufficient reactivity for the detection of virus-infected exfoliated nasopharyngeal cells. nasopharyngeal smear samples from ...19902164275
experimental infection of ponies with equine influenza (h3n8) viruses by intranasal inoculation or exposure to aerosols.infection of seronegative welsh mountain ponies was established by intranasal instillation or exposure to nebulised aerosol of egg grown h3n8 viruses. pyrexia and coughing were noted following intranasal instillation and high titres of virus were recovered from the nasopharynx. exposure to aerosol resulted in more severe clinical signs characterised by high temperatures, dyspnoea, anorexia and coughing; lower levels of virus were recovered from the nasopharynx. the severity of clinical signs and ...19902156688
outbreak of equine influenza among horses in hong kong during 1992.equine-2 influenza virus a (h3n8) infection occurred among vaccinated thoroughbred horses in hong kong during november and december 1992. the outbreak was unique in that it occurred among a large population stabled under intensive conditions. it resulted in the postponement of seven race meetings over a period of 32 days. the outbreak originated after the importation of horses 25 to 32 days before any clinical signs were reported. vaccination did not prevent 75 per cent of the population from be ...19957660556
aetiologic study on an influenza-like epidemic in horses in china.about thirty thousands horses were affected and hundreds of them died in an epidemic caused by equine 2 influenza virus (h3n8) in china. the estimated morbidity and mortality accounted for 81% and 2%, respectively. the viral protein and rna electrophoresis patterns revealed that the new isolates were antigenically different from the prototype strain influenza a/eq/miami/1/63(h3n8). therefore, the representative strain of the equine 2 subtype of influenza a virus recommended for producing referen ...19911681717
first recovery of a/equine/fontainebleau/1/79 influenza viruses in italy.in italy epizootics of equine influenza often occur, but no virus isolation has been reported since 1971. this paper describes the antigenic and biochemical characterization of two equine influenza viruses isolated in italy from 1985 to 1989. the virus isolates were shown to differ antigenically from earlier strains of the same subtype, a/equine/miami/1/63 (h3n8). monoclonal antibody analysis showed that the haemagglutinins of these strains were serologically indistinguishable from a/equine/font ...19911660798
the production of equine monoclonal immunoglobulins by horse-mouse heterohybridomas.studies were carried out to determine the optimum conditions for the production of equine monoclonal antibodies (mabs). lymphocytes from ponies immunised with influenza a equine 2 virus, isolate a/equine/newmarket/79 (h3n8) were fused with mouse myeloma (nso) cells and with horse-mouse heterohybridomas made aminopterin-sensitive by selective growth in 8-azaguanine. although all fusions initially resulted in heterohybridoma colonies that secreted equine immunoglobulin, many of these were unable t ...19921632074
interference of maternal antibodies with the immune response of foals after vaccination against equine influenza.the purpose of the study was twofold. first, using two groups of 22 foals each, we investigated the extent to which maternal antibodies interfere with the humoral response against equine influenza. the foals were born to mares that had been vaccinated twice yearly against influenza since 1982. foals of group i were vaccinated three times at early ages (12, 16, and 32 weeks of age), and foals of group ii were likewise vaccinated but a later ages (24, 28, and 44 weeks of age). after the first and ...19921574831
evolutionary pattern of the h 3 haemagglutinin of equine influenza viruses: multiple evolutionary lineages and frozen replication.the nucleotide and deduced amino acid sequences of the haemagglutinin genes coding for the ha 1 domain of h3n8 equine influenza viruses isolated over wide regions of the world were analyzed in detail to determine their evolutionary relationships. we have constructed a phylogenetic model tree by the neighbour-joining method using nucleotide sequences of 15 haemagglutinin genes, including those of five viruses determined in the present study. this gene tree revealed the existence of two major evol ...19921550498
comparative study and grouping of nonstructural (ns1) proteins of influenza a viruses by the method of oligopeptide mapping.oligopeptide mapping of 35s-methionine labeled non-structural (ns1) proteins of 23 influenza. a virus strains showed the presence of both common and variable oligopeptides. analysis of the oligopeptide maps revealed at least four groups of ns1 proteins. the first group includes ns1 proteins of several human h1n1 influenza viruses (that were designated as h0n1 according to the old classification). the second group is composed of ns1 proteins of h1n1 and h2n2 viruses. the third group includes ns1 ...19836229233
characterization of a new avian-like influenza a virus from horses in china.in march 1989 a severe outbreak of respiratory disease occurred in horses in the jilin and heilongjiang provinces of northeast china that caused up to 20% mortality in some herds. an influenza virus of the h3n8 subtype was isolated from the infected animals and was antigenically and molecularly distinguishable from the equine 2 (h3n8) viruses currently circulating in the world. the reference strain a/equine/jilin/1/89 (h3n8) was most closely related to avian h3n8 influenza viruses. sequence comp ...19921314452
maternal antibodies against equine influenza virus in foals and their interference with vaccination.foals that were born to mares vaccinated twice a year against influenza had moderate to high haemagglutination-inhibition antibody titers at 24 hours after birth. the foals were vaccinated at six and ten weeks of age, and again at three to five months after birth. four months after the third vaccination no antibodies against a/h7n7 and a/h3n8 influenza viruses were detected in these foals. thus, maternal antibodies probably prevented the development of antibodies against equine influenza virus a ...19911656657
contact infection of mink with 5 subtypes of avian influenza virus. brief report.avian influenza viruses of h3n8, h11n4, h7n7, h8n4, and h5n3 infected mink by contact.19836314940
studies with inactivated equine influenza vaccine. 2. protection against experimental infection with influenza virus a/equine/newmarket/79 (h3n8).forty ponies immunized with inactivated virus vaccine containing a/equine/miami/63 (h3n8) virus and six unvaccinated, seronegative ponies were experimentally challenged with a representative of recent equine h3n8 virus isolates, a/equine/newmarket/79. all unvaccinated ponies became infected as judged by virus excretion, febrile responses and antibody responses, but only two of the vaccinated ponies were fully protected. pre-challenge antibody levels to a/newmarket/79 virus detected by single rad ...19836306098
analysis of antigenic variation in equine 2 influenza a viruses.influenza outbreaks involving viruses of the h3n8 subtype (equine 2) often occur in vaccinated horses. for this reason, a series of influenza viruses of the h3n8 subtype were examined to determine if antigenic variation could be detected in isolates during the period 1963-81. antigenic analyses with post-infection ferret sera and monoclonal antibodies showed that the haemagglutinins of recent isolates were antigenically distinguishable from the prototype a/eq/miami/1/63 and that antigenically di ...19836601538
[antigenic drift of a strain of influenza equi virus isolated in france during the winter of 1978-1979].a strain of influenza equi virus isolated during winter 1978-1979 has been compared with influenza a/equine/miami/1/63 (h3n8) strain by cross reactions performed by radial haemolysis (rh) and hemagglutination inhibition (hai) test. specific antisera were prepared on hens and guinea-pigs. results differed according to the species on which the sera were prepared and the two methods of titration of the antibodies. hens sera were unable to differenciate by hai the newly-isolated strain influenza a/e ...19836614786
studies with inactivated equine influenza vaccine. 1. serological responses of ponies to graded doses of vaccine.serological responses to three bivalent aqueous equine influenza vaccines of different potency and an adjuvanted bivalent vaccine containing inactivated a/equine/prague/56 (h7n7) and a/equine/miami/63 (h3n8) viruses, were examined in seronegative ponies. potencies of the vaccines, measured by single-radial-diffusion tests, ranged from 4 to 56 micrograms of haemagglutinin (ha) antigen activity/virus strain per dose. serological responses to vaccination were examined by haemagglutination-inhibitio ...19836345659
human-avian influenza virus reassortants: effect of reassortment pattern on multi-cycle reproduction in mdck cells.human-avian influenza reassortants possessing the ha gene of the avian parent virus were tested for their ability to replicate in mdck cells at 37 degrees c and 31 degrees c. both avian parent viruses, a/duck/ukraine/1/63 (h3n8) and a/duck/hoshimin/014/78 (h5n3) induced an efficient multi-cycle infection at 37 degrees c, but replicated poorly at 31 degrees c, whereas the human parent virus, mdck-adapted variant of a/ussr/90/77 (h1n1) strain, replicated efficiently at both temperatures. the reass ...19883214268
[isolation of monoclonal antibodies to influenza viruses].monoclonal antibodies to influenza a/duck/ukraine/1/63 (h3n8) have been produced. comparative studies of the antigenic characteristics of hemagglutinin of different influenza virus strains isolated from humans, birds, and water were carried out. a high strain specificity of the antibodies produced was shown.19836845713
studies of a recombinant which inherited the haemagglutinin from the human influenza virus a/hong kong/1/68 (h3n2) and other genes from influenza virus a/duck/ukraine/1/63 (h3n8).a recombinant (r3/3) has been obtained which inherited the gene coding for the haemagglutinin from human influenza virus a/hong kong/1/68 (h3n2), and seven other genes from influenza virus a/duck/ukraine/1/63 (h3n8). the recombinant r3/3 had properties, a ts+ phenotype and a capability of reproducing in chick embryos, similar to those of the duck influenza virus, but, in contrast to this parent, had lost its ability to reproduce in organ cultures of colon of ducks and chickens as well as in mono ...19846693854
isolation of influenza a viruses from birds in great britain during 1980 and 1981.during 1980 and 1981 influenza a viruses of subtypes h3n2, h3n8, h4n1, h4n6, h6n2, h6n8, h7n7, h11n8 and h11n9 were isolated from birds in great britain, usually as a result of investigations of disease or death. however, all viruses were shown to be of low virulence for chickens in pathogenicity index tests. there was one occurrence of influenza virus infection of turkeys (h6n8) but viruses were frequently obtained from domestic ducks. other viruses were isolated from exotic birds in zoos or bi ...19826815876
the standardization of inactivated equine influenza vaccines by single-radial immunodiffusion.single-radial-immunodiffusion (srd) assays were used for measuring the haemagglutinin (ha) antigen content of equine influenza vaccines containing the virus strains a/equine/prague/56 (h7n7) and a/equine/miami/63 (h3n8). three bivalent aqueous vaccines and one bivalent adjuvanted vaccine were standardized by srd to contain graded amounts of ha antigen activity. the srd reaction was influenza subtype specific and was not influenced by the presence of adjuvant in vaccine.19836408096
seroepidemiological and molecular evidence for the presence of two h3n8 equine influenza viruses in china in 1993-94.in may 1993, a severe epidemic of respiratory disease began in horses in inner mongolia and spread throughout horses in china. the disease affected mules and donkeys as well as horses but did not spread to other species, including humans. the severity of the disease raised the question of whether the outbreak might have been caused by the new avian-like influenza viruses detected in horses in china in 1989 or by current variants ofa/equine/miami/1/63 (h3n8) (equine-2) or by a reassortant between ...19957636481
perpetuation of influenza a viruses in alaskan waterfowl reservoirs.to provide information on the mechanism of perpetuation of influenza viruses among waterfowl reservoirs in nature, virological surveillance was carried out in alaska during their breeding season in summer from 1991 to 1994. influenza viruses were isolated mainly from fecal samples of dabbling ducks in their nesting places in central alaska. the numbers of subtypes of 108 influenza virus isolates were 1 h2n3, 37 h3n8, 55 h4n6, 1 h7n3, 1 h8n2, 1 h10n2, 11 h10n7, and h10n9. influenza viruses were a ...19957646350
duration of protective efficacy of equine influenza immunostimulating complex/tetanus vaccines.seven previously untreated five-month-old new forest ponies received two doses of equine influenza immunostimulating complex vaccines, one with and one without an immunopurified tetanus toxoid component, given by deep intramuscular injection six weeks apart, followed by a booster dose without tetanus toxoid five months later. fifteen months after the third dose of vaccine, the ponies were challenged by exposure to an aerosol of influenza a/equine 2/sussex/89 (h3n8), a virus isolated from a recen ...19948160328
efficacy of equine influenza vaccines for protection against a/equine/jilin/89 (h3n8)--a new equine influenza virus.a new h3n8 equine influenza virus [a/equine/jilin/1/89 (eq/jilin)] appeared in northeastern china in 1989 and caused high mortality in horses; the available evidence indicates that it has not yet spread outside this region of the world. serological analysis with postinfection ferret sera in haemagglutination inhibition (hi) tests confirmed that eq/jilin is antigenically distinct from h3n8 equine influenza viruses isolated between 1963 and 1991 and also showed that a current equine influenza viru ...19938212831
[role of certain factors in intracellular oligomerization of influenza virus nucleoproteins].oligomerization of influenza virus nucleoprotein (np) depends on the virus strain. np monomers of viruses a/duck/ukraine/63 (h3n8) and a/seal/massachusets/1/80/ (h7n7) are oligomerized completely. the a/ussr/90/77 virus (h1n1) np is characterized by just partial oligomerization, similarly as a reassortant containing surface protein genes of virus a/duck/ukraine and internal protein genes of a/ussr/90 virus. hence, it is probable that np gene controls the type of np oligomerization. np oligomeriz ...19989559532
reverse genetics system for generation of an influenza a virus mutant containing a deletion of the carboxyl-terminal residue of m2 protein.we established a reverse genetics system for the m gene of influenza a virus, using amantadine resistance as a selection criterion. transfection of an artificial m ribonucleoprotein complex of a/puerto rico/8/34 (h1n1), a naturally occurring amantadine-resistant virus, and superinfection with amantadine-sensitive a/equine/miami/1/63 (h3n8), followed by cultivation in the presence of the drug, led to the generation of a transfectant virus with the a/puerto rico/8/34 (h1n1) m gene. with this syste ...19957535862
[pathogenicity of equine influenza viruses in chickens].in the present paper the pathogenicity of equine subtype a/equi 1 (h7n7) and a/equi 2 (h3n8) for chicks was studied. strains previously isolated in brazil, representatives of both subtypes, were used. eight experiments were performed for a/equi 2, using 89 chicks (4 to 18-day old). six hundred thirty three samples of cloacal material were collected from 01 to 15 days pos-infection (p.i.) and inoculated in 11-day old chick embryos for recuperation of virus. twelve samples showed positive results. ...19938303046
evolution of h3n8 equine influenza virus from 1963 to 1991.the antigenic properties of h3n8 influenza viruses isolated from outbreaks of equine influenza in sweden between 1979 and 1991 have been studied in hemagglutination inhibition tests with polyclonal and monoclonal antisera, and antigenic drift of the virus has been demonstrated. to clarify the basis of the antigenic drift, amino acid sequences of the globular head regions (ha1) of the hemagglutinin membrane glycoproteins of virus strains from 1979, 1984, 1988 and 1990 have been deduced from the n ...19947545975
production of monoclonal antibodies against equine influenza a/equi-2 (h3n8) indian isolate.seven hybrid cell lines of mouse myeloma cell line nso and spleen cells of balb/c mice producing monoclonal antibodies (mabs) against equine influenza a/equi-2/ludhiana/87 (h3n8) virus were developed. these mabs were purified, isotyped and characterised by enzyme linked immunosorbent assay (elisa), fluorescent antibody test (fat), haemagglutination inhibition (hi) and virus neutralization (vn) tests. the titres of ascitic fluids induced by hybridomas as estimated by elisa ranged from 1:25,600 to ...19938276447
the ecology of influenza viruses: a who memorandum.influenza a viruses continue to be isolated from man, pigs, horses, and a wide range of avian species, especially ducks. the recent isolation of an influenza a virus from seals has added an additional mammal to the list of natural hosts for these viruses. in contrast, influenza b viruses have been isolated only from man.the haemagglutinin of a virus isolated from gulls in the united states of america could not be identified with reference antisera and may constitute a new haemagglutinin subtype. ...19816978194
antibody responses of japanese horses to influenza viruses in the past few years.a total of 305 horse sera collected in the hidaka district of hokkaido in the years 1988-90 were tested for the presence of hemagglutination-inhibition (hi) antibodies to a/equine/newmarket/1/77 (h7n7), a/equine/tokyo/2/71 (h3n8) and a/equine/kentucky/1/81 (h3n8, kentucky) strains of equine influenza (ei) virus. antibodies to the 3 strains were detected in hardly of the 45 sera from 2-years-old horses which were collected before vaccination. many of the 51 horses, after vaccination with inactiva ...19938461424
the outbreak of equine influenza (h3n8) in the united kingdom in 1989: diagnostic use of an antigen capture elisa.in july 1989 influenza a/equine-2 (h3n8) was isolated from a nasopharyngeal swab taken from a non-thoroughbred horse exhibiting acute clinical respiratory disease. this was the first isolation of equine influenza virus in the united kingdom since 1981. subsequent investigations of acute respiratory disease in horses indicated that the infection was dispersed throughout the uk. however, unlike the previous epidemic of 1979, the first horses from which the virus was isolated had been vaccinated. t ...19938310627
equine influenza virus from the 1991 swedish epizootic shows major genetic and antigenic divergence from the prototype virus.the antigenic properties of h3n8 equine influenza virus from the swedish epizootic of 1991 differ from those of a/eq 2/fontainebleau/79 (representative of the swedish vaccine strain) in hemagglutination inhibition tests. the amino acid sequence of the hemagglutinin (ha) of an isolate from the 1991 outbreak was deduced from the nucleotide sequence and comparison was made to the a/eq 2/fontainebleau/79 strain. twenty-three amino acid substitutions were found, 10 mapping onto areas of the ha known ...19937688488
effect of influenza a/equine/h3n8 virus isolate variation on the measurement of equine antibody responses.this study has tested the effect of using homologous or heterologous equine influenza a virus isolates to evaluate serum antibody levels to influenza a virus in vaccinated and naturally-infected horses. in addition, the potential effect of antigenic selection of virus variants in egg versus tissue culture propagation systems was studied. serum antibody levels in samples from horses recently infected with a local influenza a virus isolate (a/equine 2/saskatoon/1/90) or recently vaccinated with a ...19938387870
pathogenic studies and antigenic and sequence comparisons of a/equine/alaska/1/91 (h3n8) influenza virus.an influenza virus, a/equine/alaska/1/91 (h3n8), was isolated from horses from alaska with an acute respiratory infection. pathogenic and serologic studies revealed that this virus is similar to previously isolated equine h3n8 influenza viruses. antigenic analyses utilizing hemagglutination inhibition and neuraminidase inhibition assays indicated an antigenic drift from the prototype equine h3n8 influenza virus, a/equine/miami/1/63. partial sequence analysis of the a/equine/alaska influenza viru ...19938466986
influence of host species on the evolution of the nonstructural (ns) gene of influenza a viruses.the matrix (m) and nonstructural (ns) genes of influenza a viruses each encode two overlapping proteins. in the m gene, evolution of one protein affects that of the other. to determine whether or not this evolutionary influence operating between the two m proteins also occurs in the ns gene, we sequenced the ns genes of 36 influenza a viruses isolated from a broad spectrum of animal species (wild and domestic birds, horses, pigs, humans, and sea mammals) and analyzed them phylogenetically, toget ...19989725667
diagnosis of equine influenza by the polymerase chain reaction.influenza a is a common respiratory infection of horses, and rapid diagnosis is important for its detection and control. sensitive detection of influenza currently requires viral culture and is not always feasible. the polymerase chain reaction (pcr) was used to detect dna produced by reverse transcription of equine influenza in stored nasal secretions, vaccines, and allantoic fluids. primers directed at a target of 212 bp on conserved segment 7 (matrix gene) of human influenza a/bangkok/1/79(h3 ...19948011780
defective interfering type a equine influenza virus (h3n8) protects mice from morbidity and mortality caused by homologous and heterologous subtypes of influenza a virus.intranasal administration of defective interfering a/equine/newmarket/7339/79 (h3n8) influenza virus (di eqv) protected mice from otherwise lethal intranasal infection with homologous virus (eqv) or with the heterologous subtypes a/wsn (h1n1) or a/pr/8/34 (h1n1). such protected mice showed little or no sign of clinical disease. disease with only low mortality resulting from a 'low' dose of wsn was completely prevented with a 100-fold lower dose of di eqv (4 haemagglutinating units/ml or 12 ng vi ...19947996140
antigenic and molecular characterization of host cell-mediated variants of equine h3n8 influenza viruses.antigenic differences between three of six equine influenza virus (h3n8) mdck cell- and egg-derived pairs have been demonstrated using monoclonal and polyclonal antibodies. sequencing of the haemagglutinin (ha) genes revealed amino acid changes in four of the six virus pairs. these data contrast with those for human isolates of influenza virus in that it was predominantly tissue culture-isolated equine virus and not egg-derived virus which displayed heterogeneity. some of the molecular changes i ...19948126465
antigenicity and immunogenicity of equine influenza vaccines containing a carbomer adjuvant.equine influenza vaccines containing inactivated whole virus and carbomer adjuvant stimulated higher levels and longer lasting antibody to haemagglutinin in ponies than vaccines of equivalent antigenic content containing aluminium phosphate adjuvants. five months after the third dose of vaccine containing carbomer adjuvant, ponies were protected against clinical disease induced by an aerosol of virulent influenza virus (a/equine/newmarket/79, h3n8). in contrast ponies which received vaccine cont ...19948150017
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. ...19989601502
molecular mechanisms of serum resistance of human influenza h3n2 virus and their involvement in virus adaptation in a new host.h3n2 human influenza viruses that are resistant to horse, pig, or rabbit serum possess unique amino acid mutations in their hemagglutinin (ha) protein. to determine the molecular mechanisms of this resistance, we characterized the receptor-binding properties of these mutants by measuring their affinity for total serum protein inhibitors and for soluble receptor analogs. pig serum-resistant variants displayed a markedly decreased affinity for total pig serum sialylglycoproteins (which contain pre ...19989658077
genetic and antigenic analysis of the influenza virus responsible for the 1992 hong kong equine influenza epizootic.an outbreak of influenza occurred among thoroughbred racehorses in hong kong in november-december 1992, with morbidity of 37%. all horses involved had been vaccinated against equine-1 and equine-2 influenza viruses but not against the virus responsible for the 1989 equine influenza outbreak in northern china (influenza a/equine/jilin/89, subtype h3n8). therefore the source and nature of the virus causing the hong kong outbreak was investigated. virus isolated from a horse infected during the out ...19947941336
antigenicity and immunogenicity of experimental equine influenza iscom vaccines.a comparison of the antigenicity and immunogenicity of iscom vaccines prepared from equine influenza viruses h3n8 and h7n7 was made with inactivated whole-virus vaccines containing equivalent amounts of virus haemagglutinin. iscoms stimulated superior antibody responses in terms of both amount and duration. as with conventional whole-virus vaccines, the levels of antibody to virus haemagglutinin induced by iscoms correlated with protection.19947975864
heterologous protection of mice from a lethal human h1n1 influenza a virus infection by h3n8 equine defective interfering virus: comparison of defective rna sequences isolated from the di inoculum and mouse lung.we have examined the rnas involved in the heterologous protection of adult mice from otherwise lethal intranasal infection with mouse-adapted human a/wsn (h1n1) by defective interfering (di) equine a/equine/newmarket/7339/79 (h3n8: eqv) influenza virus, as well as the rnas involved in the protection of wsn- or eqv-infected mice by their homologous di viruses. the aim of this study was to describe the types of defective rnas present in protected mice in order to guide the design of potentially pr ...19989721233
characterisation of equine influenza isolates from the 1987 epizootic in india by nucleotide sequencing of the ha1 gene.two a/equi-2 (h3n8) isolates were obtained during the 1987 indian equine influenza epizootic. the sequence of the ludhiana/87 ha1 gene revealed that this isolate was very similar to recent european and north american isolates of equine influenza. in contrast, the bhiwani/87 ha1 gene was nearly identical to the miami/63 prototype h3 sequence. these results support the antigenic analysis previously carried out on these isolates using monoclonal antibodies. however, the finding that bhiwani/87 is s ...19938385602
observations on the relationship in chickens between the virulence of some avian influenza viruses and their pathogenicity for various organs.comparative histological and immunocytochemical studies were conducted on formalin-fixed tissues from chickens infected with avian influenza viruses of varying virulence. results showed a distinct pattern of disease that depended on the virulence of the virus and the susceptibility of the birds. at 3 days post-intranasal inoculation with a highly virulent h7n7 virus, all 6-to-8-week-old specific-pathogen-free (spf) birds were affected, and all developed pancreatic necrosis and encephalitis assoc ...19958561728
single radial immunodiffusion potency test for standardization of indigenous equine influenza vaccine.single radial immunodiffusion (srd) assays were used for measuring the haemagglutinin antigen contents of equine influenza vaccine prepared from an indian virus isolate. a/equine-2/ludhiana/1/87 (h3n8). five different preparations of the vaccine were standardized by srd to prepare 913 doses, each containing 20 micrograms ha/ml-1 dose-1. this test also showed influenza virus subtype specificity as no cross reaction was observed between subtype 1 (h7n7) and subtype 2 (h3n8) viruses.19938112772
the role of antigenically different virus neuraminidases as structures implicated in receptor-binding processes.influenza a viruses exhibit segmented nucleic acid coding for eight different proteins, two of them as glycoproteins exposed on their lipoprotein envelopes, hemagglutinin (ha) and neuraminidase (na). hemagglutinin exhibits receptor-binding activity while neuraminidase develops sialidase cleavage activity which acts on cell receptors. influenza a strains responsible for human, avian, equine and porcine respiratory infections all over the world present antigenically different hemagglutinin (h1 to ...19958547843
phylogenetic analyses of the matrix and non-structural genes of equine influenza viruses.matrix (m) and nonstructural (ns) genes of thirteen equine h3n8 and h7n7 influenza viruses were sequenced and analyzed from an evolutionary point of view. the m and ns genes of h3n8 viruses isolated between 1989 and 1993 evolved into two minor branch clusters, including isolates from europe and the american continent, respectively. it was noteworthy to reveal that the nucleotide sequences of the m and ns genes of an earlier american strain showed highest homology to those of recent european viru ...19989739336
antigenic and genetic analysis of equine influenza viruses from tropical africa in 1991.a detailed analysis of equine (h3n8) influenza viruses isolated in nigeria during early 1991 has been undertaken. antigenic analysis and the complete nucleotide sequence of the ha gene of three nigerian equine influenza viruses a/eq/ibadan/4/91, a/eq/ibadan/6/91 and a/eq/ibadan/9/91 are presented and limited sequence analysis of each of the genes encoding the internal polypeptides of the virus has been carried out. these results establish that, despite the geographical location from which these ...19968870635
[complete oligomerization of the nucleoprotein and various strains of influenza virus].previously we demonstrated that in the course of intracellular reproduction of wsn influenza virus strain, part of monomeric nucleoprotein (np) undergo polymerization into dimers and trimers, which dissociate into monomers after boiling. further studies showed that different strains of influenza virus are characterized by different degree of np-oligomerization. specifically, duck/ ukraine/63 (h3n8) and seal massacuhsets 1/80 (h7n7) np monomers are completely transformed into oligomers. as a resu ...19968999311
the relationship between single radial hemolysis, hemagglutination inhibition, and virus neutralization assays used to detect antibodies specific for equine influenza viruses.antibodies specific for equine influenza viruses are usually quantified using single radial hemolysis (srh), hemagglutination inhibition (hi) or virus neutralization (vn). neutralizing antibodies are thought to provide optimum protection to challenged animals. the purpose of this study was to determine the extent to which srh and hi assays detect antibodies which neutralize equine influenza viruses. acute and convalescent sera from 41 horses were analyzed using vn, srh, and hi assays. these hors ...19957653031
equine influenza vaccine efficacy: the significance of antigenic variation.to investigate the level of cross-protection induced by equine influenza h3n8 vaccines derived from different lineages, two studies have been carried out with ponies vaccinated with 'american-like' and 'european-like' vaccines and experimentally challenged with a european-like strain. the results demonstrated that equine influenza vaccines clearly protect against challenge with homologous virus if serum antibody titres are sufficiently high. on the other hand, protection is incomplete even when ...200010799789
infectious agents in acute respiratory disease in horses in ontario.a study of acute respiratory disease in horses in ontario was undertaken to determine the identity of current causative infectious agents. a nasopharyngeal swab was designed and utilized to maximize isolation of viruses, mycoplasma, and pathogenic bacteria. serum samples were collected for parallel determination of antibody titers to equine influenza virus type a subtype 1 (h7n7) and subtype 2 (h3n8), equine rhinovirus types 1 and 2, equine herpesvirus type 1, mycoplasma equirhinius, and mycopla ...19979087920
immunogenicity and efficacy of baculovirus-expressed and dna-based equine influenza virus hemagglutinin vaccines in mice.two fundamentally different approaches to vaccination of balb/c mice with the hemagglutinin (ha) of a/equine/kentucky/1/81 (h3n8) (eq/ky) were evaluated, that is, administration of ha protein vs administration of ha-encoding dna. each vaccine was tested for its immunogenicity and ability to provide protection from homologous virus challenge. ha protein was synthesized in vitro by infection of sf21 insect cells with a recombinant baculovirus. intranasal administration of this vaccine induced viru ...19979269061
study of the duration and distribution of equine influenza virus subtype 2 (h3n8) antigens in experimentally infected ponies in vivo.the purpose of this experiment was to study the duration and distribution of equine influenza virus in actively infected ponies over a 3 wk period. pony foals (6-8 mo old) were infected experimentally by nebulizing equine influenza subtype-2 virus ultrasonically through a face mask. successful infection was clinically apparent as each of the foals (n = 6) had a febrile response, a deep hacking cough and mucopurulent nasal discharge for 7 to 10 d. the virus was isolated from nasopharyngeal swabs ...19979114962
comparison of hamster and pony challenge models for evaluation of effect of antigenic drift on cross protection afforded by equine influenza vaccines.vaccination and challenge studies in ponies are the most relevant experimental system for predicting whether strains included in equine influenza vaccines are relevant, but they are difficult to perform.200312875323
protection against a lethal avian influenza a virus in a mammalian system.the question of how best to protect the human population against a potential influenza pandemic has been raised by the recent outbreak caused by an avian h5n1 virus in hong kong. the likely strategy would be to vaccinate with a less virulent, laboratory-adapted h5n1 strain isolated previously from birds. little attention has been given, however, to dissecting the consequences of sequential exposure to serologically related influenza a viruses using contemporary immunology techniques. such experi ...19999882351
approximately 150 nucleotides from the 5' end of an influenza a segment 1 defective virion rna are needed for genome stability during passage of defective virus in infected cells.defective influenza a virus rnas analyzed in two studies so far possess at least 80-90 nucleotides from the 5' end of the virion rna segment and more typically around 200 nucleotides, whereas the 3' sequence could be as short as 25 nucleotides (p. a. jennings et al., cell 34, 619-627; 1983; s. d. duhaut and n. j. dimmock, virology 247, 241-253, 1998). to determine the biological significance of the highly conserved 5' sequence, we constructed plasmids that expressed a naturally occurring defecti ...200010998328
influenza surveillance in birds in italian wetlands (1992-1998): is there a host restricted circulation of influenza viruses in sympatric ducks and coots?we report the results of a 6-year serological and virological monitoring performed in ducks and coots in italy, in order to assess the degree of influenza a virus circulation in these birds during wintering. a total of 1039 sera collected from 1992 to 1998 was screened by a double antibody sandwich blocking elisa (np-elisa): seroprevalence of antibodies to influenza a viruses was significantly higher in ducks compared to coots (52.2% vs. 7.1%, respectively). the hemagglutination-inhibition (hi) ...200415036528
the circumstances surrounding the outbreak and spread of equine influenza in south africa.equine-2 influenza a virus (h3n8) infection first occurred among naïve horses in south africa in december 1986. the virus was introduced following the importation of six horses from the united states of america. while the release of in-contact horses from quarantine three days after the arrival of these six horses played a role in the rapid spread of the disease in south africa, other outbreaks of disease were associated with viral introduction by personnel or contaminated instruments. the contr ...199910190213
effect of moderate exercise on the severity of clinical signs associated with influenza virus infection in horses.the purpose of this experiment was to determine if exercising horses, infected with influenza virus, exacerbates the severity of clinical disease. eight horses were trained on a treadmill for 42 days and then challenged with aerosolised influenza a/equine/kentucky/91 (h3n8). following challenge, 4 horses (exercise group) continued training for 28 days, while the other 4 horses (nonexercise group) were confined to their stalls. all horses developed clinical signs within 36 h of challenge (fever, ...19989844967
strain-specific differences in the effect of influenza a virus neuraminidase on vector-expressed hemagglutinin.in order to evaluate the efficiency of the removal of sialic acid residues from the influenza virus hemagglutinin by the viral neuraminidase in the course of the virus replication cycle, cv-1 cells expressing the hemagglutinin of h7 subtype from an sv40-based vector were superinfected with influenza virus strain a/duck/ukraine/63 (h3n8) or a/ussr/90/77 (h1n1). vector-expressed hemagglutinin was immunoprecipitated from cell lysates and analyzed by polyacrylamide gel electrophoresis. the data indi ...199910365168
efficacy of a commercial vaccine for preventing disease caused by influenza virus infection in horses.to evaluate efficacy of a commercial vaccine for prevention of infectious upper respiratory tract disease (iurd) caused by equine influenza virus.199910397067
a pcr based method for the identification of equine influenza virus from clinical samples.in this paper we describe the development of a nested rt-pcr assay for the rapid diagnosis and characterisation of influenza virus directly from clinical specimens. viral rna is extracted from nasal swabs by the guanidine thiocyanate extraction method, and subsequently reverse transcribed. the complementary dna is then used as template in a nested pcr reaction. primers designed for use in this assay are specific for three templates; (1) the nucleoprotein (np) gene, (2) the haemagglutinin gene of ...199910418871
cocirculation of two distinct lineages of equine influenza virus subtype h3n8.direct amplification and sequencing of the hemagglutinin (ha) genes of equine influenza virus subtype h3n8 was undertaken in order to characterize strains of this virus circulating in sweden. the majority of viruses from outbreaks during 1997 analyzed belonged to the american lineage of h3 equine influenza, and one strain was shown to belong to the european lineage. furthermore, it was shown that recent american-lineage strains are mutated at amino acid position 190 of the ha during serial passa ...199910449491
cultures of equine respiratory epithelial cells and organ explants as tools for the study of equine influenza virus infection.equine nasal turbinate epithelial cells and tracheal rafts were maintained with sustained viability in culture. both types of culture supported productive replication of equine influenza virus (equine-2, subtype h3n8) and cell death occurred through apoptosis following viral infection. thus, primary respiratory epithelial cell and organ cultures of equine origin may be valuable as alternatives to the intact animal for studying the virus-host interaction of equine respiratory viruses including in ...200111765925
plasma glutamine status in the equine at rest, during exercise and following viral challenge.the variation over 24 h of plasma glutamine concentration in nonexercising horses was studied in 3 thoroughbreds (tb) fed at 1600 h and 0700 h. this indicated a small but regular change associated with feeding. starting at a mean of 482 mumol/l at 1600 h the concentration increased to 522 mumol/l at 2000 h, falling to 476 mumol/l at 1600 h and increasing again to 525 mumol/l at 2000 h. 'normal' values were established in 19 part-bred tb horses, lacking clinical signs or remarkable pathology and ...199910659329
identification of two antigenically and genetically distinct lineages of h3n8 equine influenza virus in sweden.four swedish strains of equine h3n8 influenza virus isolated from outbreaks during the last 4 years were characterized. antigenic typing using monoclonal antibodies raised against a variety of h3n8 strains showed that the viruses are heterogeneous, the 1993 isolate being closely related to the 1991 swedish isolate tab/91 and the other three isolates from 1994 and 1996 being more closely related to each other. this pattern is reflected in the phylogenetic data calculated from nucleotide sequencin ...19989528819
characterization of the influenza a virus gene pool in avian species in southern china: was h6n1 a derivative or a precursor of h5n1?in 1997, an h5n1 influenza virus outbreak occurred in chickens in hong kong, and the virus was transmitted directly to humans. because there is limited information about the avian influenza virus reservoir in that region, we genetically characterized virus strains isolated in hong kong during the 1997 outbreak. we sequenced the gene segments of a heterogeneous group of viruses of seven different serotypes (h3n8, h4n8, h6n1, h6n9, h11n1, h11n9, and h11n8) isolated from various bird species. the p ...200010864640
investigations on the ability of clenbuterol hydrochloride to reduce clinical signs and inflammation associated with equine influenza a infection.twenty-four quarter horse and quarter horse-cross yearlings were experimentally infected with influenza a virus (influenza a/equine/saskatoon/90 [h3n8]) by nebulisation. in a double blind controlled trial the horses were randomly assigned to 3 groups of 8 animals. group 1 received a placebo, (carrier syrup), group 2 the labelled dose and group 3 twice the labelled dose of clenbuterol hydrochloride. all treatments were given per os b.i.d. for 10 days and started on the day of infection. the horse ...199910213429
replacement of internal protein genes, with the exception of the matrix, in equine 1 viruses by equine 2 influenza virus genes during evolution in nature.to establish the evolutionary association between the equine 1 h7 ha and m genes, phylogenetic analyses of the six internal gene segments of equine 1 influenza viruses (h7n7 subtype) were performed using partial nucleotide sequences. the results demonstrated that five internal genes (pbi, pb2, pa, np and ns) of equine 1 viruses isolated after 1964 were replaced by those of equine 2 h3n8 viruses. however, the m gene was maintained during the evolution of these equine 1 viruses. these findings sug ...199910487248
defective influenza a virus generated entirely from plasmids: its rna is expressed in infected mouse lung and modulates disease.naturally produced defective influenza virus has antiviral activity and, in sufficient amount, can protect mice from lethal influenza, irrespective of the virus subtype causing the disease. however, such defective virus preparations contain many undefined defective rna sequences, and it is thus not possible to establish dose-response relationships. to address this situation, we have transfected dna encoding a cloned defective rna into vero cells along with the 17 a/wsn (h1n1) plasmids required f ...200312565156
direct sequencing of the ha gene of clinical equine h3n8 influenza virus and comparison with laboratory derived viruses.equine influenza viruses propagated in the laboratory in alternate hosts such as embryonated hens' eggs or mammalian cell culture have been analysed by ha sequencing and antigenically and their sequence compared to the original virus present in clinical material. in contrast to clinically derived human influenza virus which generally grows in mdck cells without change, the data for equine influenza virus were less clear in that variants of equine virus were derived in both eggs and cells. the st ...19989645196
diverged evolution of recent equine-2 influenza (h3n8) viruses in the western hemisphere.we reported previously that equine-2 influenza a virus (h3n8) had evolved into two genetically and antigenically distinct "eurasian" and "american" lineages. phylogenetic analysis, using the ha1 gene of more recent american isolates, indicated a further divergence of these viruses into three evolution lineages: a south american lineage, a kentucky lineage, and a florida lineage. these multiple evolution pathways were not due to geographic barriers, as viruses from different lineages co-circulate ...200111504416
the involvement of a stress-activated pathway in equine influenza virus-mediated apoptosis.we have shown elsewhere that equine-2 influenza virus (eiv; subtype h3n8) induced pronounced cell death in infected cells through apoptosis as demonstrated by dna fragmentation assay and a combined tunel and immunostaining scheme. in this study, we investigated the mechanism of eiv-mediated cytotoxicity on a permissive mammalian epithelial cell line, madin-darby canine kidney (mdck) cells. eiv infection increased the cellular levels of oxidative stress and c-jun/ap-1 protein (which is known to b ...200111504555
defective segment 1 rnas that interfere with production of infectious influenza a virus require at least 150 nucleotides of 5' sequence: evidence from a plasmid-driven system.the presence of at least 80-90 and more typically around 200 nucleotides (nt) at the 5' end of the virion-sense rna in all naturally occurring defective influenza a virus rnas suggests that this is essential sequence, whereas the 3'-end sequence may be as short as 25 nt. the stability of defective rna on serial passage with infectious helper virus also depends on the length of 5'-end sequence. here, we have studied the influence of 5'-end sequences of a panel of six defective segment 1 rnas from ...200211807233
an epizootic of equine influenza in upper egypt in 2000.this study describes an epizootic of respiratory tract disease caused by influenza virus infection in a large population of equines in luxor and aswan, upper egypt, during the winter of 2000. the epizootic started in january and the infection rate reached its peak in february before gradually decreasing until the end of april, 2000. horses, donkeys and mules of all ages and both sexes were affected. free movement of the infected equines and direct contact between the animals at markets facilitat ...200415861887
efficacy and duration of immunity of a combined equine influenza and equine herpesvirus vaccine against challenge with an american-like equine influenza virus (a/equi-2/kentucky/95).it has been recommended that modern equine influenza vaccines should contain an a/equi-1 strain and a/equi-2 strains of the american and european-like subtype. we describe here the efficacy of a modern updated inactivated equine influenza-herpesvirus combination vaccine against challenge with a recent american-like isolate of equine influenza (a/equine-2/kentucky/95 (h3n8). the vaccine contains inactivated influenza strains a-equine-1/prague'56, a-equine-2/newmarket-1/'93 (american lineage) and ...200414975389
[extracellular immunoreactive nucleoprotein of influenza virus not related to the virion].extracellular immunoreactive virus np is accumulated in virus-containing fluid in the course of a/duck/ukraine/1/63(h3n8) influenza virus infection. the major part of this extracellular np is included in viral rnp and characterized by relatively low molecular weight: 53 kd vs. 56 kd of virion np. extracellular immunoreactive np is oligomerized. presumably, there is partially intracellular cleavage of np with loss of hydrophobic determinants. such truncated np in rnp is highly hydrophilic and pas ...200111450139
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