| prevalence of antibodies to type a influenza viruses in swine sera 1990-1994. | a total of 3,120 swine sera collected for the years 1990-94 were tested for the presence of hemagglutination-inhibition (hi) antibodies against swine (h1n1) and human (h1n1 and h3n2) strains of influenza virus. no hi antibody against the swine strains was recognized during 18 months, though a slight prevalence (1.5-9.2%) of the antibodies was observed over the entire period. a wide variance in the incidence (0-26.3%) of antibodies against the human h3n2 strains was observed among the swine popul ... | 1995 | 8519918 |
| epitope mapping of cross-reactive monoclonal antibodies specific for the influenza a virus pa and pb2 polypeptides. | characterization of the epitopes recognized by 21 monoclonal antibodies (mabs) specific for the influenza a virus pa (13 mabs) and pb2 (8 mabs) polypeptides (bárcena et al. (1994) j. virol. 68, 6900-6909) raised against denatured polypeptides produced in e. coli is described. mabs were characterized by: (1) competitive binding elisas; (2) mapping of the protein regions that specify their binding sites; and (3) analyses of their ability to recognize the corresponding viral protein in a number of ... | 1995 | 8533465 |
| enhancement of humoral response against human influenza vaccine with the simple submicron oil/water emulsion adjuvant mf59. | human influenza subunit vaccines are not fully protective in either the very young or elderly populations where risk is greatest. the use of an adjuvant to enhance antibody titer is an attractive option to increase vaccine efficacy. a series of squalene/h2o emulsions stabilized either by the amphipathic muramyl peptide mtp-pe (sodium n-acetyl-muramyl-l-alanyl-d-isoglutaminyl-l-alanyl-2-(1',2'-dipalmitoyl- sn- glycero-3'phospho) ethylamide) or by mixtures of the sorbitan oleate surfactants tween ... | 1995 | 8578842 |
| cooperation between government and industry in combating a perceived emerging pandemic. the 1976 swine influenza vaccination program. | | 1996 | 8604179 |
| influenza infection in humans and pigs in southeastern china. | the three last pandemic strains of influenza a virus-asian/57, hong kong/68 and russian/77-are believed to have originated in china. the strains responsible for the 1957 and 1968 human pandemics were reassortants incorporating both human and avian influenza viruses, which may have arisen in pigs. we therefore undertook a population-based study in the nanchang region of central china to establish the prevalence, types and seasonal pattern of human influenza infection and to screen serum samples f ... | 1996 | 8645101 |
| antigenic and genetic analyses of the hemagglutinin of influenza viruses isolated from pigs in 1993. | three strains of influenza a virus (h3n2) were isolated from pigs in hokkaido, japan in 1993. the hemagglutinin (ha) antigen of the three isolates was related to that of recent h3n2 viruses of human origin. the reactivity patterns of two of the isolates (a/sw/obihiro/1/93 and a/sw/obihiro/2/93) with monoclonal antibodies to the hemagglutinin of a/bangkok/1/79 strain were similar to that of the human h3n2 strain isolated in hokkaido in 1988, while that of the other one (a/sw/obihiro/3/93) was sim ... | 1995 | 8720040 |
| [the relationship between integrated fish farming and human influenza pandemic]. | the study was carried out for reviewing the hypothesis on the relationship between integrated fish farming (iff) and human influenza a pandemic using study methods of longitudinal epidemiology, ecology and serology. four rural villages with iff, non-iff and non-fish farming, selected from two provinces (henan and shandong of prc) were investigated for the status about human influenza a epidemic and infections with human, duck, swine influenaz a viruses in those communities. the results put forwa ... | 1996 | 8758416 |
| large outbreak of swine influenza in southern japan caused by reassortant (h1n2) influenza viruses: its epizootic background and characterization of the causative viruses. | in the winter of 1989 and the spring of 1990, there were large outbreaks of respiratory disease in two swine herds in nagasaki prefecture, southern japan. serological surveillance indicated that the majority of swine possessed antibodies to swine influenza virus h1 haemagglutinin and neuraminidase of early h3n2 influenza virus strains. eight viruses were isolated from swine that showed typical clinical symptoms of influenza. the haemagglutinin and neuraminidase of these isolates were closely rel ... | 1996 | 8760422 |
| two evolutionary strategies of influenza viruses to escape host non-specific inhibitors: alteration of hemagglutinin or neuraminidase specificity. | the porcine serum inhibitor alpha 2-macroglobulin prevents influenza virus from entering host cells by competing for the sa alpha 2, 6gal-binding site of the hemagglutinin (ha). we studied a series of inhibitor-sensitive and inhibitor-resistant human and porcine influenza virus isolates of the h3n2 subtype, all of which contained has, which initially bound only to sa alpha 2, 6gal oligosaccharides. when their neuraminidase was inhibited, the naturally resistant viruses, as a result of no longer ... | 1996 | 8806180 |
| intracellular oligomerization of influenza virus nucleoprotein. | it has previously been shown that the purified influenza virus nucleoprotein (np) forms the oligomers in vitro in np preparations obtained from virions (wiley et al., 1977, virology, 79, 446-448; ruigrok and baudin, 1995, j. gen. virol., 76, 1009-1014) and infected cells (becht and weiss, 1991, behring inst mitt., justus-liebig universitat, giessen, 89, 1-11). we have shown in this report that boiling-sensitive np oligomers (di- and trimers) are formed in vivo in the course of intracellular infl ... | 1996 | 8806539 |
| genetic reassortment in pandemic and interpandemic influenza viruses. a study of 122 viruses infecting humans. | the human influenza pandemics of 1957 and 1968 were caused by reassortant viruses that possessed internal gene segments from avian and human strains. whether genetic reassortment of human and avian influenza viruses occurs during interpandemic periods and how often humans are infected with such reassortants is not known. to provide this information, we used dot-blot hybridization, partial nucleotide sequencing and subsequent phylogenetic analysis to examine the 6 internal genes of 122 viruses is ... | 1996 | 8817180 |
| molecular evolution of influenza viruses. | there are two different mechanisms by which influenza viruses might evolve: (1) because the rna genome of influenza viruses is segmented, new strains can suddenly be produced by reassortment, as happens, for example, during antigenic shift, creating new pandemic strains. (2) new viruses evolve relatively slowly by stepwise mutation and selection, for example, during antigenic or genetic drift. influenza a viruses were found in various vertebrate species, where they form reservoirs that do not ea ... | 1995 | 8828147 |
| emergence of avian h1n1 influenza viruses in pigs in china. | avian influenza a viruses from asia are recognized as the source of genes that reassorted with human viral genes to generate the asian/57 (h2n2) and hong kong/68 (h3n2) pandemic strains earlier in this century. here we report the genetic analysis of avian influenza a h1n1 viruses recently isolated from pigs in southern china, a host suspected to generate new pandemic strains through gene reassortment events. each of the eight gene segments was of avian origin. phylogenetic analysis indicates tha ... | 1996 | 8892928 |
| evaluation of a protective immunity induced by an inactivated influenza h3n2 vaccine after an intratracheal challenge of pigs. | a challenge study was conducted to evaluate the safety and efficacy of an inactivated influenza h3n2 virus vaccine combined with quil a/alhydrogel mixture under controlled conditions in piglets. twenty-four piglets from 12 sows were allocated to 2 groups; injected intramuscularly with 2 doses of the tested vaccine or with pbs at 2 wk intervals and challenged intratracheally with 105tcid50 of the h3n2 swine influenza virus 6 d after the 2nd immunization. clinical and virological parameters were r ... | 1996 | 8904668 |
| a serological survey of influenza a antibody in human and pig sera in calcutta. | a study was undertaken with a view to assess the distinct pattern of sero-prevalence of influenza a viruses in the city of calcutta population during the years of 1981-90. concurrently, based on the fact of increasing pig population, a study was carried out to establish the activity of the human influenza a virus among pigs with a view to the potential threat of emergence of a new strain of influenza a virus that may surface following co-infection with swine and human influenza a viruses. the pe ... | 1995 | 8919937 |
| transmission of swine influenza virus to humans after exposure to experimentally infected pigs. | two people developed symptoms of influenza 36 h after collecting nasal swabs from pigs experimentally infected with a/sw/in/1726/88 (sw/in). pharyngeal swabs from these persons tested positive for influenza virus rna 8 days after infection. analysis of hemi-nested polymerase chain reaction (pcr) products indicated that the hemagglutinin (ha) segments of the isolates were genetically related to the ha of sw/in. four influenza a virus isolates (a/wi/4754/94, a/wi/4756/94, a/wi/4758/94, a/wi/4760/9 ... | 1997 | 8985190 |
| antigenic and genetic analyses of h1n1 influenza a viruses from european pigs. | h1n1 influenza a viruses isolated from pigs in europe since 1981 were examined both antigenically and genetically and compared with h1n1 viruses from other sources. h1n1 viruses from pigs and birds could be divided into three groups: avian, classical swine and 'avian-like' swine viruses. low or no reactivity of 'avian-like' swine viruses in hi tests with monoclonal antibodies raised against classical swine viruses was associated with amino acid substitutions within antigenic sites of the haemagg ... | 1997 | 9049404 |
| dual infections of feeder pigs with porcine reproductive and respiratory syndrome virus followed by porcine respiratory coronavirus or swine influenza virus: a clinical and virological study. | dual infections of pigs with porcine reproductive and respiratory syndrome virus (prrsv) followed by a second common respiratory virus, either porcine respiratory coronavirus (prcv) or swine influenza virus (siv), were studied. the aim was to determine if dual infections, as compared to single virus infections, result in enhanced clinical manifestations. it was also examined if prrsv replication affects replication of prcv or siv in the respiratory tract. groups of conventional 10 week old pigs ... | 1996 | 9054128 |
| initial genetic characterization of the 1918 "spanish" influenza virus. | the "spanish" influenza pandemic killed at least 20 million people in 1918-1919, making it the worst infectious pandemic in history. understanding the origins of the 1918 virus and the basis for its exceptional virulence may aid in the prediction of future influenza pandemics. rna from a victim of the 1918 pandemic was isolated from a formalin-fixed, paraffin-embedded, lung tissue sample. nine fragments of viral rna were sequenced from the coding regions of hemagglutinin, neuraminidase, nucleopr ... | 1997 | 9065404 |
| [the threat of an influenza pandemic]. | | 1995 | 9081824 |
| swine influenza virus strains recognize sialylsugar chains containing the molecular species of sialic acid predominantly present in the swine tracheal epithelium. | we determined the ratio of n-glycolylneuraminic acid (neu5gc) to n-acetylneuraminic acid (neu5ac) in swine respiratory epithelia by fluorometric high-performance liquid chromatography, and examined the binding specificity of swine influenza virus strains for gangliosides containing different molecular species of sialic acid (neu5ac and neu5gc), and for bovine erythrocyte sialoglycoprotein 2 (gp-2) containing neu5gc as its predominate sialic acid (96% of total sialic acids). the presence of neu5g ... | 1997 | 9119062 |
| first genes isolated from the deadly 1918 flu virus. | | 1997 | 9122676 |
| genomic study of hemagglutinins of swine influenza (h1n1) viruses associated with acute and chronic respiratory diseases in pigs. | the nucleotide sequences of ha1 domain of hemagglutinin of clinical h1n1 influenza viruses, isolated during recent outbreaks of respiratory problems in pig farms of quebec, was determined. the viruses a/sw/quebec/3291/90 (swqc3291) and a/sw/quebec/1747/90 (swqc1747), associated with chronic respiratory disease, showed close similarity for their deduced aa sequences. when compared with the published data of a/sw/quebec/5393/91 (swqc91), the variations observed included cb and ca antigenic sites i ... | 1997 | 9125053 |
| continued evolution of h1n1 and h3n2 influenza viruses in pigs in italy. | swine influenza viruses possessing avian genes were first detected in europe in 1979 (scholtissek et al., 1983, virology, 129, 521-523) and continue to circulate in pigs in that region of the world. to characterize the molecular epidemiology of swine influenza viruses currently circulating in europe, we used dot-blot hybridization and sequence analysis to determine the origin of the genes encoding the nonsurface proteins ("internal" genes) of 10 h1n1 and 11 h3n2 swine influenza viruses isolated ... | 1997 | 9191844 |
| genetic characterisation of an influenza a virus of unusual subtype (h1n7) isolated from pigs in england. | an h1n7 influenza a virus, isolated from pigs in england in 1992, was examined genetically to determine the characteristics and probable origin of the eight gene segments. six of the rna segments encoding pb2, pb1, pa, ha, np and ns were related most closely to those of human viruses, whilst two of the rna segments (na and m) were related most closely to those of equine viruses. the ha gene was most similar to that of a/ussr/90/77 (h1n1) but amino acid differences suggested independent genetic d ... | 1997 | 9191869 |
| a monoclonal-antibody-based immunohistochemical method for the detection of swine influenza virus in formalin-fixed, paraffin-embedded tissues. | | 1997 | 9211240 |
| microbiological monitoring of laboratory pigs. | purpose-bred minipigs, are often used as the non-rodent species in toxicology. infections may interfere with animal experiments, and there are no scientific reasons why the non-rodent species should be of a lower microbiological quality than the rodent species. therefore, a system for health monitoring of pigs was developed in order to raise the quality of laboratory pigs to the level of laboratory rodents. this system, which includes screening for several viruses, bacteria and ecto- and endopar ... | 1997 | 9230498 |
| pandemic influenza: confronting a re-emergent threat. the 1976 experience. | the swine influenza immunization program began in january 1976 with an outbreak of swine influenza among trainees at ft. dix, new jersey. the program ended in december 1976 after an increased incidence of guillain-barre syndrome was attributed to the vaccine. the issues and events of 1976 provide valuable lessons for the future. a thorough and objective review of the swine flu program should be a prerequisite for influenza pandemic planning. strong consideration should be given to creating separ ... | 1997 | 9240699 |
| macrophages and respiratory viruses. | this review highlights some of the interactions between alveolar macrophages and human/swine influenza a viruses, porcine reproductive and respiratory syndrome virus (prrsv), bovine parainfluenza type-3 (pi-3) virus, bovine respiratory syncytial virus (brsv) and bovine viral diarrhoea virus (bvdv). in influenza a infection, macrophage-cytokines are believed to mediate the typical constitutional effects and inflammation in the respiratory tract. the same cytokines possibly play a role in influenz ... | 1997 | 9247041 |
| neuraminidase hemadsorption activity, conserved in avian influenza a viruses, does not influence viral replication in ducks. | the n1 and n9 neuraminidase (na) subtypes of influenza a viruses exhibit significant hemadsorption activity that localizes to a site distinct from that of the enzymatic active site. to determine the conservation of hemadsorption activity among different nas, we have examined most of the na subtypes from avian, swine, equine, and human virus isolates. all subtypes of avian virus nas examined and one equine virus n8 na possessed high levels of hemadsorption activity. a swine virus n1 na exhibited ... | 1997 | 9261394 |
| stimulation of antiviral activities of interferon by a liver extract preparation. | the liver extract preparation adelavin9 (referred to as ext-fad hereinafter) is a combination product that consists of hog liver extract and flavin-adenine dinucleotide (fad). ext-fad has been reported to improve the histology of chronic liver injury and is widely used in japan. interferon (ifn) has been used to treat viral hepatitis. in this study, the action of ext-fad on the antiviral activity of ifn was examined using experimental models of viral infection in vitro and in vivo. ext-fad signi ... | 1997 | 9296286 |
| complete sequences of the neuraminidase genes of swine influenza viruses (h1n1) associated with the respiratory disease in pigs. | the complete nucleotide sequences of neuraminidase (na) of two swine influenza viruses (h1n1) are presented. a/sw/quebec/5393/91 (swqc91) virus, associated with the chronic respiratory disease and a/sw/ quebec/192/81 (swqc81) virus, associated with the acute respiratory disease, were used. the deduced amino acid sequences of na of swqc91 and swqc81 viruses showed a high degree (>95%) of similarity. the na gene of both viruses was a single open reading frame of 1459 nucleotides coding for 469 aa ... | 1997 | 9311570 |
| cleavage of influenza a virus h1 hemagglutinin by swine respiratory bacterial proteases. | cleavage of influenza a virus hemagglutinin (ha) is required for expression of fusion activity and virus entry into cells. extracellular proteases are responsible for the proteolytic cleavage activation of avirulent avian and mammalian influenza viruses and contribute to pathogenicity and tissue tropism. the relative contributions of host and microbial proteases to cleavage activation in natural infection remain to be established. we examined 23 respiratory bacterial pathogens and 150 aerobic ba ... | 1997 | 9311838 |
| structural evidence for a second sialic acid binding site in avian influenza virus neuraminidases. | the x-ray structure of a complex of sialic acid (neu5ac) with neuraminidase n9 subtype from a/tern/australia/g70c/75 influenza virus at 4 degrees c has revealed the location of a second neu5ac binding site on the surface of the enzyme. at 18 degrees c, only the enzyme active site contains bound neu5ac. neu5ac binds in the second site in the chair conformation in a similar way to which it binds to hemagglutinin. the residues that interact with neu5ac at this second site are mostly conserved in av ... | 1997 | 9342319 |
| prevalence of swine influenza and other viral, bacterial, and parasitic zoonoses in veterinarians. | | 1997 | 9359752 |
| [history of influenza epidemics and discovery of influenza virus]. | influenza epidemics occur almost annually, sometimes taking on a global scale and turning into pandemics. according to noble, the first clearly recorded epidemic was one that struck europe in 1173 to 1174. in japan the first comprehensive review of epidemic records was made by fujikawa in the early 20th century, who listed 46 epidemics between 862 and 1868. of the ten pandemics since the 1700s that have been certified by beveridge nine have struck japan as well. the human influenza a virus was d ... | 1997 | 9360364 |
| [the virological, epidemiological and clinical features of influenza a, b and c viruses]. | influenza epidemics that start abruptly and spread rapidly are caused by either influenza a or b virus. although well-defined outbreaks of influenza c have rarely been reported, influenza c virus has been shown to cause a mild upper respiratory illness in children as well as in adults. influenza a virus naturally infects several mammalian species including humans as well as a variety of avian species, whereas influenza b virus infects only humans. influenza c virus primarily infects humans but h ... | 1997 | 9360366 |
| manipulation of immune responses via particle-mediated polynucleotide vaccines. | polynucleotide vaccines are a new approach to immunization that promises qualitative advances in vaccine technology. these vaccines mimic infection in that they result in expression of pathogen gene products in situ, which can elicit both cell-mediated immune responses and humoral responses. this approach has been applied primarily to vaccines against viral diseases, but may be significant for vaccines directed toward bacterial pathogens. auragen has developed a generally applicable gene transfe ... | 1997 | 9382772 |
| inhibition of several strains of influenza virus in vitro and reduction of symptoms by an elderberry extract (sambucus nigra l.) during an outbreak of influenza b panama. | a standardized elderberry extract, sambucol (sam), reduced hemagglutination and inhibited replication of human influenza viruses type a/shangdong 9/93 (h3n2), a/beijing 32/92 (h3n2), a/texas 36/91 (h1n1), a/singapore 6/86 (h1n1), type b/panama 45/90, b/yamagata 16/88, b/ann arbor 1/86, and of animal strains from northern european swine and turkeys, a/sw/ger 2/81, a/tur/ger 3/91, and a/sw/ger 8533/91 in madin-darby canine kidney cells. a placebo-controlled, double blind study was carried out on a ... | 1995 | 9395631 |
| influenza virus: transmission between species and relevance to emergence of the next human pandemic. | although influenza viruses are not spread from human to human through the conventional food chain, this is not necessarily the case for the transmission of the precursors of the human pandemic influenza viruses. aquatic birds of the world are the reservoirs for all influenza a viruses; the virus is spread by fecal-oral transmission in untreated water. influenza a viruses are frequently transmitted to domestic poultry and two of the 15 subtypes h5 and h7 can become highly pathogenic and have the ... | 1997 | 9413531 |
| immunization of pigs with a particle-mediated dna vaccine to influenza a virus protects against challenge with homologous virus. | particle-mediated delivery of a dna expression vector encoding the hemagglutinin (ha) of an h1n1 influenza virus (a/swine/indiana/1726/88) to porcine epidermis elicits a humoral immune response and accelerates the clearance of virus in pigs following a homotypic challenge. mucosal administration of the ha expression plasmid elicits an immune response that is qualitatively different than that elicited by the epidermal vaccination in terms of inhibition of the initial virus infection. in contrast, ... | 1998 | 9445052 |
| serological studies on porcine pneumocystis carinii pneumonia: kinetics of the antibody titers in swine herds and the association of porcine reproductive and respiratory syndrome virus infection. | serological titers to pneumocystis carinii (pc) and porcine reproductive and respiratory syndrome virus (prrsv) were measured on a herd with epidemic pc pneumonia (case herd) and two comparison herds, by an indirect fluorescent-antibody technique. in the case herd, the geometric mean titer (gmt) for pc were 1:80 in pigs 1 week old, 1:10 in pigs 5 weeks old, and 1:80 to 1:190 in pigs over 6 weeks old. gmts for prrsv were > 1:145 in most of age groups over 7 weeks old. in comparison herds, pc and ... | 1997 | 9450249 |
| fatal case of swine influenza virus in an immunocompetent host. | swine influenza virus (siv), a common zoonotic infection, affects swine, particularly during late autumn and winter. transmission of siv from pigs to humans has been reported occasionally; most cases are mild infections and rarely lead to death. herein we describe an immunocompetent woman in whom the adult respiratory distress syndrome developed; she died of a fulminant course of swine influenza. the documented pathogen was the h1n1 strain of siv. to our knowledge, only four other deaths in immu ... | 1998 | 9511782 |
| bronchoalveolar interferon-alpha, tumor necrosis factor-alpha, interleukin-1, and inflammation during acute influenza in pigs: a possible model for humans? | biologically active interferon-alpha, tumor necrosis factor-alpha (tnf-alpha), and interleukin-1 (il-1) were detected in bronchoalveolar lavage (bal) fluids of 3-week-old cesarian-derived colostrum-deprived pigs inoculated with h1n1 influenza virus. cytokine titers and lung virus titers were significantly higher 18-24 h after inoculation than at 48-72 h after inoculation in all 4 litters of pigs examined. all three cytokines were positively correlated with a 3- to 4-fold increase in bal cell num ... | 1998 | 9534986 |
| influenza virus-infected epithelial cells present viral antigens to antigen-specific cd8+ cytotoxic t lymphocytes. | we have investigated the mechanisms involved in the clearance of viral infection at the epithelium level by analyzing the activity of influenza virus-specific cytotoxic t lymphocytes (ctl) against virus-infected cmt-93 intestinal epithelial cells. epithelial cells infected with live influenza virus effectively present viral antigens and were lysed by both homotypic and heterotypic influenza virus-specific cd8+ t cells. these results shed new light on the control of viral infection through the el ... | 1998 | 9557755 |
| [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 ... | 1998 | 9559532 |
| is china an influenza epicentre? | | 1997 | 9594271 |
| [the threat of an influenza pandemic]. | | 1998 | 9611870 |
| veterinarians integral in resolving avian influenza incidents, developing vaccine. | | 1998 | 9621872 |
| membrane-anchored incorporation of a foreign protein in recombinant influenza virions. | the rna polymerase i system for in vivo synthesis of recombinant influenza vrna molecules was used for the expression of a chimeric protein, consisting of the 341-amino-acid ectodomain of the glycoprotein e2 of classical swine fever virus and the 37-amino-acid c-terminal membrane anchor of the influenza virus hemagglutinin (ha). during infection with an influenza a helper virus the amplified pseudo-viral rna was packaged into progeny virions together with influenza vrna segments. the foreign fus ... | 1998 | 9656996 |
| 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 ... | 1998 | 9658077 |
| multiple alignment comparison of the non-structural genes of influenza a viruses. | one hundred and six influenza a virus isolates were compared phylogenetically using gene segment 8 which encodes the two non-structural (ns) proteins, ns1 and ns2. the isolates separated into two previously described subtypes, a and b. for non-structural gene subtype a viruses, five subdivisions were distinguished in the nucleotide phylogenetic tree including a human-swine group, american avian-equine group, eurasian avian-swine group, a unique gull isolate group, and a group with a single membe ... | 1998 | 9660072 |
| molecular basis for the generation in pigs of influenza a viruses with pandemic potential. | genetic and biologic observations suggest that pigs may serve as "mixing vessels" for the generation of human-avian influenza a virus reassortants, similar to those responsible for the 1957 and 1968 pandemics. here we demonstrate a structural basis for this hypothesis. cell surface receptors for both human and avian influenza viruses were identified in the pig trachea, providing a milieu conducive to viral replication and genetic reassortment. surprisingly, with continued replication, some avian ... | 1998 | 9696833 |
| differences in the biological phenotype of low-yielding (l) and high-yielding (h) variants of swine influenza virus a/nj/11/76 are associated with their different receptor-binding activity. | low- (l) and high-yielding (h) variants of a/sw/nj/11/76 influenza virus were compared for their growth properties in embryonated chicken eggs and mdck cells and for their binding affinity for the membrane fractions prepared from cells of the chicken embryo allantoic membrane. mdck, and swine tracheal cells, as well as for soluble sialic acid containing macromolecules and monovalent sialosides. we have shown, that during infection in mdck cells and in eggs, the progeny of the l variant remain pr ... | 1998 | 9705915 |
| 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 ... | 1998 | 9725667 |
| in vivo gene transfer to skin and wound by microseeding. | gene transfer to skin has many potential applications but lacks a safe, practical delivery method. this report presents a new technique, microseeding, for in vivo gene transfer to skin and wounds and for dna-mediated vaccination. the plasmid dna solution was delivered directly to the target cells of the skin by a set of oscillating solid microneedles driven by a modified tattooing device. | 1998 | 9733623 |
| changes in h3 influenza a virus receptor specificity during replication in humans. | influenza a viruses of the h3 subtype caused the 1968 hong kong pandemic, the hemagglutinin (ha) gene being introduced into humans following a reassortment event with an avian virus. receptor specificity and serum inhibitor sensitivity of the ha of influenza a viruses are linked to the host species. human h3 viruses preferentially recognize n-acetyl sialic acid linked to galactose by alpha2,6 linkages (neu5acalpha2,6gal) and are sensitive to serum inhibitors, whereas avian and equine viruses pre ... | 1998 | 9783465 |
| continued circulation of reassortant h1n2 influenza viruses in pigs in japan. | in 1991 and 1992, h1n2 influenza a viruses were isolated from the lungs of pigs with overt signs of respiratory disease at farms in the chiba and kanagawa prefectures of japan. to determine the genetic origin of these isolates, we phylogenetically analyzed partial nucleotide sequences of their genes. the results indicate that influenza viruses possessing the n2 of human influenza virus and seven other gene segments of classical h1n1 swine influenza virus, which were first isolated in 1980, have ... | 1998 | 9787660 |
| serosurvey of selected viral and bacterial diseases in wild swine from oklahoma. | blood samples collected from 120 wild swine (sus scrofa) in thirteen oklahoma (usa) counties during 1996 were tested for antibodies against six viral and two bacterial diseases. no antibodies to swine brucellosis, pseudorabies, transmissible gastroenteritis, and vesicular stomatitis were detected. antibody titers to one or more leptospiral serovars were found in 44% of the samples, the two most frequent serovars being leptospira interrogans serovars bratislava (29%) and pomona (27%). antibody ag ... | 1998 | 9813859 |
| synthesis and evaluation of some masked phosphate esters of the anti-herpesvirus drug 882c (netivudine) as potential antiviral agents. | a number of symmetric and asymmetric 5'-phosphate esters of the potent anti-varicella-zoster virus (vzv) agent 1-(beta-d-arabinofuranosyl)-5-prop-1-ynyluracil (882c; netivudine) were prepared as potential lipophilic, membrane-soluble prodrugs of the bio-active phosphate forms. the compounds were prepared by the base-catalysed coupling of various phosphorochloridates with the free nucleoside analogue. compounds were fully characterized by a range of spectroscopic and analytical methods and were s ... | 1998 | 9875402 |
| characterization of avian h5n1 influenza viruses from poultry in hong kong. | the transmission of avian h5n1 influenza viruses to 18 humans in hong kong in 1997 with six deaths established that avian influenza viruses can transmit to and cause lethal infection in humans. this report characterizes the antigenic and biological properties of the h5n1 influenza viruses isolated from chickens, ducks, and geese from farms and poultry markets in hong kong during 1997 and compares them with those of virus isolated from the index human case. each of the h5n1 viruses from hong kong ... | 1998 | 9878612 |
| multiple genetic reassortment of avian and human influenza a viruses in european pigs, resulting in the emergence of an h1n2 virus of novel genotype. | novel h1n2 influenza a viruses which were first detected in pigs in great britain in 1994 were examined antigenically and genetically to determine their origins and establish the potential mechanisms for genetic reassortment. the haemagglutinin (ha) of all swine h 1 n2 viruses examined was most closely related to, but clearly distinguishable both antigenically and genetically from, the ha of human h1n1 viruses which circulated in the human population during the early 1 980s. phylogenetic analysi ... | 1998 | 9880008 |
| independence of evolutionary and mutational rates after transmission of avian influenza viruses to swine. | in 1979, an h1n1 avian influenza virus crossed the species barrier, establishing a new lineage in european swine. because there is no direct or serologic evidence of previous h1n1 strains in these pigs, these isolates provide a model for studying early evolution of influenza viruses. the evolutionary rates of both the coding and noncoding changes of the h1n1 swine strains are higher than those of human and classic swine influenza a viruses. in addition, early h1n1 swine isolates show a marked pl ... | 1999 | 9971766 |
| [role of antineuraminidase antibodies in protection against influenza]. | for improving the anti-influenza vaccination efficacy, the choice of strains carrying up dated neuraminidase antigen (na) and the introduction of the optimal amount of na antigen in the vaccine are critical. monoclonal antibodies prepared against the neuraminidase n2 of a/beijing/32/92 showed na inhibition (ni) and neutralized (nt) the cells infection by influenza virus either at an early stage (group 2 antibodies inhibit virus binding to cells) or at a late stage of infection (group 1 antibodie ... | 1998 | 10188318 |
| antigenic drift in swine influenza h3 haemagglutinins with implications for vaccination policy. | in order to explore the occurrence of antigenic drift in swine influenza a(h3n2) virus, we examined virus strains from outbreaks of respiratory disease among finishing pigs in the netherlands in 1996 and 1997 and from earlier outbreaks. in contrast to swine h3n2 strains from the 1980s, the recent isolates did not show significant cross-reactivity with human influenza a(h3n2) viruses from 1972-1975 in haemagglutination inhibition tests. these new strains form a separate branch in the phylogenetic ... | 1999 | 10195767 |
| the 1918 'spanish' flu: pearls from swine? | | 1999 | 10202925 |
| the swine flu immunization program: a comparison of inoculation recipients and nonrecipients. | | 1978 | 10315848 |
| improving health care planning--some lessons from immunization. | this article presents a managerial perspective on health planning by the federal government illustrated by the case of the swine flu immunization program. the recent national program in the u.s.a. for immunizing the entire population against the swine flu is examined in terms of the processes of health planning. it is concluded that this program was poorly planned and therefore doomed to failure from the beginning. recommendations for improved planning of similar programs are made. | 1984 | 10316078 |
| human cd8+ and cd4+ t lymphocyte memory to influenza a viruses of swine and avian species. | recently, an avian influenza a virus (a/hong kong/156/97, h5n1) was isolated from a young child who had a fatal influenza illness. all eight rna segments were of avian origin. the h5 hemagglutinin is not recognized by neutralizing abs present in humans as a result of infection with the human h1, h2, or h3 subtypes of influenza a viruses. subsequently, five other deaths and several more human infections in hong kong were associated with this avian-derived virus. we investigated whether influenza ... | 1999 | 10358215 |
| amino acid residues contributing to the substrate specificity of the influenza a virus neuraminidase. | influenza a viruses possess two glycoprotein spikes on the virion surface: hemagglutinin (ha), which binds to oligosaccharides containing terminal sialic acid, and neuraminidase (na), which removes terminal sialic acid from oligosaccharides. hence, the interplay between these receptor-binding and receptor-destroying functions assumes major importance in viral replication. in contrast to the well-characterized role of ha in host range restriction of influenza viruses, there is only limited inform ... | 1999 | 10400772 |
| risk indicators for the seroprevalence of mycoplasma hyopneumoniae, porcine influenza viruses and aujeszky's disease virus in slaughter pigs from fattening pig herds. | epidemiological aspects of mycoplasma hyopneumoniae (mh), influenza h1n1 and h3n2 viruses, and aujeszky's disease virus (adv) were investigated in slaughter pigs from 50 fattening pig herds. herd factors as potential risk indicators for respiratory disease were obtained by means of a questionnaire. at slaughter, blood samples were collected from each herd, and the proportion of seropositive pigs per herd was assessed for each of these pathogens. the median herd-level seroprevalence of the agents ... | 1999 | 10416368 |
| differential production of proinflammatory cytokines in the pig lung during different respiratory virus infections: correlations with pathogenicity. | the acute stages of infection with swine influenza virus (siv), porcine respiratory coronavirus (prcv) and porcine reproductive-respiratory syndrome virus (prrsv) were shown to differ in terms of clinical and lung inflammatory effects and proinflammatory cytokine profiles in bronchoalveolar lavage (bal) fluids. caesarian-derived colostrum-deprived pigs were inoculated intratracheally with one of the three viruses. siv infection was followed within 1 day post inoculation (d pi) by characteristic ... | 1999 | 10425240 |
| survey of infectious agents involved in acute respiratory disease in finishing pigs. | outbreaks of respiratory disease constitute a major health problem in herds of finishing pigs and their aetiology often remains unclear. in this study, 16 outbreaks of respiratory disease with acute clinical signs in finishing pigs were investigated to determine which infectious agents were involved. from each herd four diseased and two clinically healthy pigs were examined pathologically and for the presence of viruses, bacteria and mycoplasmas. in addition, paired blood samples from 10 groupma ... | 1999 | 10466829 |
| genetic reassortment of avian, swine, and human influenza a viruses in american pigs. | in late summer through early winter of 1998, there were several outbreaks of respiratory disease in the swine herds of north carolina, texas, minnesota, and iowa. four viral isolates from outbreaks in different states were analyzed genetically. genotyping and phylogenetic analyses demonstrated that the four swine viruses had emerged through two different pathways. the north carolina isolate is the product of genetic reassortment between h3n2 human and classic swine h1n1 influenza viruses, while ... | 1999 | 10482643 |
| [influenza pandemics: past and future]. | the circulation of numerous influenza virus subtypes in water birds constitutes a continuous threat with respect to emergence of a future influenza pandemic. the interspecies barrier is high but has already been breached 3 times this century, notably in 1918, 1957 and 1968. still, it is impossible to predict when another pandemic will occur. continuous and intensive surveillance of influenza viruses in man, pigs, and birds, especially in china, may provide the opportunity to prepare a vaccine ti ... | 1999 | 10535054 |
| caspase-dependent n-terminal cleavage of influenza virus nucleocapsid protein in infected cells. | the nucleocapsid protein (np) (56 kda) of human influenza a viruses is cleaved in infected cells into a 53-kda form. likewise, influenza b virus np (64 kda) is cleaved into a 55-kda protein with a 62-kda intermediate (o. p. zhirnov and a. g. bukrinskaya, virology 109:174-179, 1981). we show now that an antibody specific for the n terminus of influenza a virus np reacted with the uncleaved 56-kda form but not with the truncated np53 form, indicating the removal of a 3-kda peptide from the n termi ... | 1999 | 10559331 |
| influenza a virus recycling revisited. | current textbooks link influenza pandemics to influenza a virus subtypes h2 (1889-91), h3 (1990), h1 (1918-20), h2 (1957-58) and h3 (1968), a pattern suggesting subtype recycling in humans. since h1 reappeared in 1977, whatever its origin, some workers feel that h2 is the next pandemic candidate. this report reviews the publications on which the concept of influenza a virus subtype recycling is based and concludes that the data are inconsistent with the purported sequence of events. the three in ... | 1999 | 10593030 |
| h3n2 influenza a virus recovered from a neonatal pig in ontario--1997. | | 1999 | 10646069 |
| [evaluation of an optical immunoassay test for rapid detection of influenza a and b viral antigen]. | an optical immunoassay test, flu oia (biostar, usa), was evaluated for the diagnosis of influenza viral infection. the reactivity of the flu oia test was evaluated using 42 influenza strains (25 human influenza a, 12 human influenza b, 2 swine influenza a and 3 avian influenza a strains). the flu oia test showed positive results for all influenza strains. there was no evidence that cross-reactivity occurred with non-influenza viruses. the detection limit of the flu oia test was found to be 3.0-6 ... | 1999 | 10655680 |
| the swine flu vaccine and guillain-barré syndrome. a case study in relative risk and specific causation. | epidemiologic methods were developed to prove general causation: identifying exposures that increase the risk of particular diseases. courts often are more interested in specific causation: on balance of probabilities, was the plaintiff's disease caused by exposure to the agent in question? some authorities have suggested that a relative risk greater than 2.0 meets the standard of proof for specific causation. such a definite criterion is appealing, but there are difficulties. bias and confoundi ... | 1999 | 10662072 |
| characterization of the pathogenicity of members of the newly established h9n2 influenza virus lineages in asia. | the reported transmission of avian h9n2 influenza viruses to humans and the isolation of these viruses from hong kong poultry markets lend urgency to studies of their ecology and pathogenicity. we found that h9n2 viruses from north america differ from those of asia. the north american viruses, which infect primarily domestic turkeys, replicated poorly in inoculated chickens. phylogenetic analysis of the hemagglutinin and nucleoprotein genes indicated that the asian h9n2 influenza viruses could b ... | 2000 | 10662623 |
| [inter-species transmission of the influenza virus]. | influenza is an infection of human beings and several animal species. it is caused by influenza viruses which belong to the orthomyxoviridae family. type a influenza viruses are the most important as they cause severe epidemics and are responsible of important pathological troubles. type a influenza viruses are classified in different sub-types depending of the nature of their surface glycoproteins: haemagglutinin (h) and neuraminidase (n). the nature of the genome and the mode of replication of ... | 1999 | 10687244 |
| influenza a pandemics of the 20th century with special reference to 1918: virology, pathology and epidemiology. | influenza a virus initiated worldwide epidemics (pandemics) in 1918, 1957, 1968 and 1977. a revised calculation of the 1918-1919 pandemic estimates that 40 million persons died and 500 million were infected. the mortalities in 1957 and 1968 were nearly 6 million. biological and genetic characteristics of the causative agents of the more recent pandemics, have been well studied but little is known about the causative agent of the great pandemic in 1918. genetic characterisation of the 1918 virus ... | 2000 | 10713598 |
| proinflammatory cytokines and viral respiratory disease in pigs. | swine influenza virus (siv), porcine respiratory coronavirus (prcv) and porcine reproductive and respiratory syndrome virus (prrsv) are enzootic viruses causing pulmonary infections in pigs. the first part of this review concentrates on known clinical and pathogenetic features of these infections. siv is a primary respiratory pathogen; prcv and prrsv, on the contrary, tend to cause subclinical infections if uncomplicated but they appear to be important contributors to multifactorial respiratory ... | 2000 | 10779199 |
| ebv-based plasmid dna rearrangements after transfection of eukaryotic cells. | the cdna encoding influenza virus (a/udorn/307/72 strain) m2 protein was subcloned into the ebv-based vector prep9. three continuous kidney cellular lines of different origin were transfected with recombinant plasmid prep9-m2. one and 5 months after transfection plasmid dna rearrangements were detected by means of restriction analysis of recovered plasmids and their hybridization with an influenza-virus-specific radioactive probe. deletions were the most frequent type of prep9-m2 mutations. pcr ... | 2000 | 10783296 |
| evolution of avian influenza viruses. | although influenza viruses can infect a wide variety of birds and mammals, the natural host of the virus is wild waterfowl, shorebirds, and gulls. when other species of animals, including chickens, turkeys, swine, horses, and humans, are infected with influenza viruses, they are considered aberrant hosts. the distinction between the normal and aberrant host is important when describing virus evolution in the different host groups. the evolutionary rate of influenza virus in the natural host rese ... | 2000 | 10799775 |
| emergence of h3n2 reassortant influenza a viruses in north american pigs. | in late summer through early winter of 1998, there were several outbreaks of respiratory disease in the swine herds of north carolina, texas, minnesota and iowa. four viral isolates from outbreaks in different states were analyzed, both antigenically and genetically. all of the isolates were identified as h3n2 influenza viruses with antigenic profiles similar to those of recent human h3 strains. genotyping and phylogenetic analysis demonstrated that the four swine viruses had emerged through two ... | 2000 | 10799777 |
| the influenza a virus m1 protein interacts with the cellular receptor of activated c kinase (rack) 1 and can be phosphorylated by protein kinase c. | the m1 protein of influenza a virus has multiple regulatory functions during the infectious cycle, which include mediation of nuclear export of viral ribonucleoproteins, inhibition of viral transcription and a crucial role in virus assembly and budding. the only known modification of the m1 protein is by phosphorylation through yet-to-be-identified kinases. we postulated that at least some of the m1 functions are exerted or regulated through interactions with cellular components. in a screen for ... | 2000 | 10799781 |
| systemic and mucosal immune responses to h1n1 influenza virus infection in pigs. | influenza is a common respiratory disease in pigs, and since swine influenza viruses are zoonotic pathogens, they also pose human health risks. pigs infected with influenza virus mount an effective immune response and are protected from subsequent challenge, whereas the currently available, inactivated-virus vaccine does not consistently confer complete protection to challenge. to develop and evaluate new vaccination strategies, it is imperative to fully understand the immune responses that are ... | 2000 | 10799784 |
| interspecies transmission of influenza viruses: h5n1 virus and a hong kong sar perspective. | this account takes stock of events and involvements, particularly on the avian side of the influenza h5n1 'bird flu' incident in hong kong sar in 1997. it highlights the role of the chicken in the many live poultry markets as the source of the virus for humans. the slaughter of chicken and other poultry across the sar seemingly averted an influenza pandemic. this perspective from hong kong sar marks the coming-of-age of acceptance of the role of avian hosts as a source of pandemic human influenz ... | 2000 | 10799786 |
| dna vaccination against influenza viruses: a review with emphasis on equine and swine influenza. | the influenza virus vaccines that are commercially-available for humans, horses and pigs in the united states are inactivated, whole-virus or subunit vaccines. while these vaccines may decrease the incidence and severity of clinical disease, they do not consistently provide complete protection from virus infection. dna vaccines are a novel alternative to conventional vaccination strategies, and offer many of the potential benefits of live virus vaccines without their risks. in particular, becaus ... | 2000 | 10799787 |
| a longitudinal study of serological patterns of respiratory infections in nine infected danish swine herds. | sixteen litters of seven pigs from each of nine danish farrow-to-finish herds were followed to investigate the serological patterns caused by natural infection with mycoplasma hyopneumoniae, pasteurella multocida toxin and actinobacillus pleuropneumoniae serotypes 2, 5-7, 12. in seven of the herds, pigs were followed as two separate cohorts started 4 weeks apart, and in two herds only one cohort was followed.a total of 999 pigs were included in the study. the pigs were blood sampled at weaning a ... | 2000 | 10821962 |
| mast cell tryptase from pig lungs triggers infection by pneumotropic sendai and influenza a viruses. purification and characterization. | a novel trypsin-type serine proteinase, which processes the precursors of the envelope fusion glycoproteins of pneumotropic sendai and human influenza a viruses, was purified to homogeneity from pig lungs. on sds/page, the purified enzyme gave a protein band corresponding to about 32 kda, and has an apparent molecular mass of 120 kda, as determined by gel permeation chromatography. immunohistochemical staining with antibodies against this enzyme revealed that the enzyme is located in pig lung ma ... | 2000 | 10824103 |
| isolations of h1n2 influenza a virus from pigs in belgium. | | 2000 | 10839238 |
| type- and subtype-specific rt-pcr assays for avian influenza a viruses (aiv). | reverse transcriptase (rt) pcr assays have been developed to improve the diagnosis of avian influenza a. rt-pcr using primers complementary to a conserved region of the matrix protein was assessed as being suitable for the detection of influenza a virus rna from poultry as well as from pigs, horses and humans, regardless of the haemagglutinin (ha) and neuraminidase (na) subtype. therefore, this rt-pcr is a valuable tool to confirm the initial diagnosis of any influenza a infection. as a second a ... | 2000 | 10861198 |
| 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 ... | 2000 | 10864640 |
| systemic and mucosal isotype-specific antibody responses in pigs to experimental influenza virus infection. | the immunoglobulin isotype-specific responses in serum and at the respiratory mucosa of pigs after a primary infection with influenza virus were studied. to do this, we developed an aerosol challenge model for influenza in specified pathogen-free (spf) pigs and isotype-specific enzyme-linked immunosorbent assays (elisas). ten-week-old pigs were inoculated without anesthesia in the nostrils with an aerosol of the field isolate influenza a/swine/neth/st. oedenrode/96 (h3n2). the infection caused a ... | 2000 | 10893003 |
| the susceptibility of culture cells to avian influenza viruses. | the susceptibilities of culture cells to twelve avian influenza virus strains were determined with ten established cell lines including mdck and esk cells and three primary culture cells. the established cell lines derived from embryonic swine kidney (esk) and chicken kidney (ck) primary culture cells were more sensitive to the avian influenza viruses than the other eleven cells. the esk cell had a particularly higher infective titer than the mdck cell with and without trypsin supplement in cult ... | 2000 | 10907697 |
| genetic characterization of h3n2 influenza viruses isolated from pigs in north america, 1977-1999: evidence for wholly human and reassortant virus genotypes. | since 1998, h3n2 viruses have caused epizootics of respiratory disease in pigs throughout the major swine production regions of the u.s. these outbreaks are remarkable because swine influenza in north america had previously been caused almost exclusively by h1n1 viruses. we sequenced the full-length protein coding regions of all eight rna segments from four h3n2 viruses that we isolated from pigs in the midwestern u.s. between march 1998 and march 1999, as well as from h3n2 viruses recovered fro ... | 2000 | 10930664 |
| interspecies transmission and receptor recognition of influenza a viruses. | | 2000 | 10941924 |