| evolution of swine h3n2 influenza viruses in the united states. | during 1998, severe outbreaks of influenza were observed in four swine herds in the united states. this event was unique because the causative agents, h3n2 influenza viruses, are infrequently isolated from swine in north america. two antigenically distinct reassortant viruses (h3n2) were isolated from infected animals: a double-reassortant virus containing genes similar to those of human and swine viruses, and a triple-reassortant virus containing genes similar to those of human, swine, and avia ... | 2000 | 10954521 |
| early alterations of the receptor-binding properties of h1, h2, and h3 avian influenza virus hemagglutinins after their introduction into mammals. | interspecies transmission of influenza a viruses circulating in wild aquatic birds occasionally results in influenza outbreaks in mammals, including humans. to identify early changes in the receptor binding properties of the avian virus hemagglutinin (ha) after interspecies transmission and to determine the amino acid substitutions responsible for these alterations, we studied the has of the initial isolates from the human pandemics of 1957 (h2n2) and 1968 (h3n2), the european swine epizootic of ... | 2000 | 10954551 |
| virologic and serologic surveillance for human, swine and avian influenza virus infections among pigs in the north-central united states. | influenza virus infection in pigs is both an animal health problem and a public health concern. as such, surveillance and characterization of influenza viruses in swine is important to the veterinary community and should be a part of human pandemic preparedness planning. studies in 1976/1977 and 1988/1989 demonstrated that pigs in the u.s. were commonly infected with classical swine h1n1 viruses, whereas human h3 and avian influenza virus infections were very rare. in contrast, human h3 and avia ... | 2000 | 10963345 |
| isolation and characterization of h4n6 avian influenza viruses from pigs with pneumonia in canada. | in october 1999, h4n6 influenza a viruses were isolated from pigs with pneumonia on a commercial swine farm in canada. phylogenetic analyses of the sequences of all eight viral rna segments demonstrated that these are wholly avian influenza viruses of the north american lineage. to our knowledge, this is the first report of interspecies transmission of an avian h4 influenza virus to domestic pigs under natural conditions. | 2000 | 10982381 |
| comparison of serologic testing and slaughter evaluation for assessing the effects of subclinical infection on growth in pigs. | to compare serologic testing with slaughter evaluation in assessing effects of subclinical infection on average daily weight gain (adg) in pigs. | 2000 | 10997163 |
| [comparison of 2 techniques for the laboratory diagnosis of influenza virus infections]. | the clinical or epidemiological influenza diagnosis require fast, sensitive and accessible techniques for small laboratories. in order to investigate the sensitivity of the methods currently used in argentina, the rapid diagnosis by indirect immunofluorescent assay (if) was compared to the rapid viral culture in mdck cells. the diagnosis of influenza virus infection was performed on 81 nasal and pharyngeal swabs collected from outpatients with upper respiratory infection, influenza-like syndrome ... | 2000 | 11008706 |
| influenza a virus neuraminidase: regions of the protein potentially involved in virus-host interactions. | phylogenetically informative amino acid positions (pips) were identified in influenza a neuraminidases of subtypes n1 and n2. neuraminidase evolves in a lineage-specific way as the virus adapts to a new host or changes to evade the host's immune system. thus, many pips undoubtedly identify positions involved in virus-host interactions. phylogenetically important regions (pirs) are defined as several pips near one another. there are 15 pirs on n1 and 12 on n2, seven of which are shared between th ... | 2000 | 11040132 |
| detection of influenza a viruses from different species by pcr amplification of conserved sequences in the matrix gene. | the recently raised awareness of the threat of a new influenza pandemic has stimulated interest in the detection of influenza a viruses in human as well as animal secretions. virus isolation alone is unsatisfactory for this purpose because of its inherent limited sensitivity and the lack of host cells that are universally permissive to all influenza a viruses. previously described pcr methods are more sensitive but are targeted predominantly at virus strains currently circulating in humans, sinc ... | 2000 | 11060074 |
| potency of a genetically detoxified mucosal adjuvant derived from the heat-labile enterotoxin of escherichia coli (ltk63) is not adversely affected by the presence of preexisting immunity to the adjuvant. | the objective of the current studies was to evaluate whether the potency of a genetically detoxified mucosal adjuvant, derived from heat-labile enterotoxin of escherichia coli (ltk63), was adversely affected by preexisting immunity. studies of mice and pigs have involved consecutive intranasal immunization with ltk63 and 2 different vaccines (influenza virus hemagglutinin and a protein-polysaccharide conjugate of neisseria meningitidis group c). the antibody responses to the vaccines plus ltk63 ... | 2001 | 11110644 |
| expression of a foreign epitope by porcine reproductive and respiratory syndrome virus. | the potential of porcine reproductive and respiratory syndrome virus (prrsv) as a viral vector was explored by the insertion of a sequence encoding a foreign antigen into the infectious cdna clone of the lelystad virus isolate. an epitope of the hemagglutinin (ha) protein of human influenza a virus was introduced at the 5' end and at the 3' end of orf7, in each case resulting in a fusion protein between the ha epitope and the nucleocapsid (n) protein. furthermore, in the construct carrying the h ... | 2000 | 11118361 |
| genomic analysis of matrix gene and antigenic studies of its gene product (m1) of a swine influenza virus (h1n1) causing chronic respiratory disease in pigs. | the nucleotide sequence of gene coding for the matrix protein (m1 and m2) of swine influenza (h1n1) virus, a/sw/quebec/5393/91 (swqc91), associated with chronic respiratory disease in pigs, was determined. the deduced amino acid (aa) sequence was compared with the other north american swine strains including the a/sw/quebec/192/81 (swqc81) strain associated with the chronic and acute respiratory disease in pigs. separate analysis of the m1 and m2 gene products showed different evolutions. m1 had ... | 2000 | 11129631 |
| h4n6 influenza virus isolated from pigs in ontario. | | 2000 | 11143928 |
| recent zoonoses caused by influenza a viruses. | influenza is a highly contagious, acute illness which has afflicted humans and animals since ancient times. influenza viruses are part of the orthomyxoviridae family and are grouped into types a, b and c according to antigenic characteristics of the core proteins. influenza a viruses infect a large variety of animal species, including humans, pigs, horses, sea mammals and birds, occasionally producing devastating pandemics in humans, such as in 1918, when over twenty million deaths occurred worl ... | 2000 | 11189716 |
| sequence of the 1918 pandemic influenza virus nonstructural gene (ns) segment and characterization of recombinant viruses bearing the 1918 ns genes. | the influenza a virus pandemic of 1918-1919 resulted in an estimated 20-40 million deaths worldwide. the hemagglutinin and neuraminidase sequences of the 1918 virus were previously determined. we here report the sequence of the a/brevig mission/1/18 (h1n1) virus nonstructural (ns) segment encoding two proteins, ns1 and nuclear export protein. phylogenetically, these genes appear to be close to the common ancestor of subsequent human and classical swine strain ns genes. recently, the influenza a ... | 2001 | 11226311 |
| a comparison of diagnostic assays for the detection of type a swine influenza virus from nasal swabs and lungs. | nasal swabs and lung samples from pigs experimentally infected with h1n1 swine influenza virus (siv) were examined for the presence of siv by the indirect fluorescent antibody assay, immunohistochemistry, cell culture virus isolation, egg inoculation, and 2 human enzyme immunoassays (membrane enzyme immunoassay, microwell enzyme immunoassay). egg inoculation was considered to be the gold standard for assay evaluation. the 2 human enzyme immunoassays (eia) and egg inoculation agreed 100% for the ... | 2001 | 11243361 |
| detection and subtyping (h5 and h7) of avian type a influenza virus by reverse transcription-pcr and pcr-elisa. | avian influenza virus infections are a major cause of morbidity and rapid identification of the virus has important clinical, economical and epidemiological implications. we have developed a one-tube reverse transcriptase polymerase chain reaction (rt-pcr) for the rapid diagnosis of avian influenza a. a panel of reference influenza strains from various hosts including avian species, human, swine and horse were evaluated in a one tube rt-pcr using primers designed for the amplification of a 218 b ... | 2001 | 11266220 |
| antigenic and genetic characterization of swine influenza a (h1n1) viruses isolated from pneumonia patients in the netherlands. | it is generally believed that pigs can serve as an intermediate host for the transmission of avian influenza viruses to humans or as mixing vessels for the generation of avian-human reassortant viruses. here we describe the antigenic and genetic characterization of two influenza a (h1n1) viruses, which were isolated in the netherlands from two patients who suffered from pneumonia. both viruses proved to be antigenically and genetically similar to avian-like swine influenza a (h1n1) viruses which ... | 2001 | 11289812 |
| infection of a child in hong kong by an influenza a h3n2 virus closely related to viruses circulating in european pigs. | influenza virus a/hong kong/1774/99, isolated from a young child with mild influenza, was shown to be similar in its antigenic and genetic characteristics to h3n2 viruses circulating in pigs in europe during the 1990s and in particular to be closely related to viruses isolated from two children in the netherlands in 1993. similar viruses had previously not been identified outside europe. although there is little evidence as to how the child contracted the infection, it appears likely that pigs i ... | 2001 | 11369884 |
| interaction between mycoplasma hyopneumoniae and swine influenza virus. | an experimental respiratory model was used to investigate the interaction between mycoplasma hyopneumoniae and swine influenza virus (siv) in the induction of pneumonia in susceptible swine. previous studies demonstrated that m. hyopneumoniae, which produces a chronic bronchopneumonia in swine, potentiates a viral pneumonia induced by the porcine reproductive and respiratory syndrome virus (prrsv). in this study, pigs were inoculated with m. hyopneumoniae 21 days prior to inoculation with siv. c ... | 2001 | 11427564 |
| duck and human pandemic influenza a viruses retain sialidase activity under low ph conditions. | the majority of influenza a viruses isolated from wild birds, but not humans, can replicate in the duck intestinal tract. here we demonstrate that all duck isolates tested universally retain sialidase activities under low ph conditions independent of their neuraminidase (na) subtypes. in contrast, the sialidase activities of most isolates from humans and pigs practically disappear below ph 4.5, with the exception of four human pandemic viruses isolated in 1957 and 1968. sequence comparisons amon ... | 2001 | 11481046 |
| antigenic and molecular heterogeneity in recent swine influenza a(h1n1) virus isolates with possible implications for vaccination policy. | in order to explore the occurrence of antigenic drift in swine influenza a(h1n1) viruses and the match between epidemic and vaccine strains, 26 virus isolates from outbreaks of respiratory disease among finishing pigs in the netherlands in the 1995/1996 season and reference strains from earlier outbreaks were examined using serological and molecular methods. in contrast to swine h3n2 viruses, no significant antigenic drift was observed in swine h1n1 viruses isolated from the late 1980s up to 199 ... | 2001 | 11483271 |
| efficacy of vaccination of pigs with different h1n1 swine influenza viruses using a recent challenge strain and different parameters of protection. | this study investigates whether antigenic evolution within h1n1 swine influenza viruses can compromise vaccine efficacy and, specifically, whether the a/new jersey/8/76 strain in the commercial swine influenza vaccines needs to be updated. pigs were vaccinated twice intramuscularly with experimental monovalent vaccines derived from different h1n1 strains (a/new jersey/8/76, sw/belgium/1/83 or sw/belgium/1/98) or with a commercial bivalent vaccine based on a/new jersey/8/76 (h1n1) and a/port chal ... | 2001 | 11483274 |
| a unique phosphatidylinositol bearing a novel branched-chain fatty acid from rhodococcus equi binds to influenza virus hemagglutinin and inhibits the infection of cells. | from the aquatic bacterium rhodococcus equi strain s(420), we isolated a substance that strongly binds to influenza viruses. structural analyses revealed that it is a unique type of phosphatidylinositol (ptdins) bearing a branched-chain fatty acid (14-methyloctadecanoic acid). in a tlc/virus-binding immunostaining assay, this ptdins bound to all subtypes of hemagglutinin (ha) of influenza a viruses tested, isolated from humans, ducks and swine, and also to human influenza b viruses. furthermore, ... | 2001 | 11530013 |
| serum amyloid p component inhibits influenza a virus infections: in vitro and in vivo studies. | serum amyloid p component (sap) binds in vitro ca(2+)-dependently to several ligands including oligosaccharides with terminal mannose and galactose. we have earlier reported that sap binds to human influenza a virus strains, inhibiting hemagglutinin (ha) activity and virus infectivity in vitro. these studies were extended to comprise five mouse-adapted influenza a strains, two swine influenza a strains, a mink influenza a virus, a ferret influenza a reassortant virus, a influenza b virus and a p ... | 2001 | 11530187 |
| virology. a molecular whodunit. | | 2001 | 11546856 |
| recombination in the hemagglutinin gene of the 1918 "spanish flu". | when gene sequences from the influenza virus that caused the 1918 pandemic were first compared with those of related viruses, they yielded few clues about its origins and virulence. our reanalysis indicates that the hemagglutinin gene, a key virulence determinant, originated by recombination. the "globular domain" of the 1918 hemagglutinin protein was encoded by a part of a gene derived from a swine-lineage influenza, whereas the "stalk" was encoded by parts derived from a human-lineage influenz ... | 2001 | 11546876 |
| analysis of the quality of protection induced by a porcine influenza a vaccine to challenge with an h3n2 virus. | antigenic drift of swine influenza a (h3n2) viruses away from the human a/port chalmers/1/73 (h3n2) strain, used in current commercial swine influenza vaccines, has been demonstrated in the netherlands and belgium. therefore, replacement of this human strain by a more recent swine h3n2 isolate has to be considered. in this study, the efficacy of a current commercial swine influenza vaccine to protect pigs against a recent dutch field strain (a/sw/oedenrode/96) was assessed. to evaluate the level ... | 2001 | 11557293 |
| cocirculation of avian h9n2 and contemporary "human" h3n2 influenza a viruses in pigs in southeastern china: potential for genetic reassortment? | pigs are permissive to both human and avian influenza viruses and have been proposed to be an intermediate host for the genesis of pandemic influenza viruses through reassortment or adaptation of avian viruses. prospective virological surveillance carried out between march 1998 and june 2000 in hong kong, special administrative region, people's republic of china, on pigs imported from southeastern china, provides the first evidence of interspecies transmission of avian h9n2 viruses to pigs and d ... | 2001 | 11559800 |
| x-ray structures of h5 avian and h9 swine influenza virus hemagglutinins bound to avian and human receptor analogs. | the three-dimensional structures of avian h5 and swine h9 influenza hemagglutinins (has) from viruses closely related to those that caused outbreaks of human disease in hong kong in 1997 and 1999 were determined bound to avian and human cell receptor analogs. emerging influenza pandemics have been accompanied by the evolution of receptor-binding specificity from the preference of avian viruses for sialic acid receptors in alpha2,3 linkage to the preference of human viruses for alpha2,6 linkages. ... | 2001 | 11562490 |
| respiratory and systemic humoral and cellular immune responses of pigs to a heterosubtypic influenza a virus infection. | the level of heterosubtypic immunity (het-i) and the immune mechanisms stimulated by a heterosubtypic influenza virus infection were investigated in pigs. pigs are natural hosts for influenza virus and, like humans, they host both subtypes h1n1 and h3n2. marked het-i was observed when pigs were infected with h1n1 and subsequently challenged with h3n2. after challenge with h3n2, pigs infected earlier with h1n1 did not develop fever and showed reduced virus excretion compared with non-immune contr ... | 2001 | 11602782 |
| combined pcr-heteroduplex mobility assay for detection and differentiation of influenza a viruses from different animal species. | transfer of influenza a viruses from animal hosts to man may lead to the emergence of new human pandemic strains. the early detection and identification of such events are therefore paramount in the surveillance of influenza viruses. to detect and partially characterize influenza a viruses from different animal species, a combined reverse transcription (rt)-pcr heteroduplex mobility assay (hma) was designed. this m gene rt-pcr was shown to be sensitive and specific for the detection of human, av ... | 2001 | 11682536 |
| a novel influenza a virus mitochondrial protein that induces cell death. | while searching for alternative reading-frame peptides encoded by influenza a virus that are recognized by cd8+ t cells, we found an abundant immunogenic peptide encoded by the +1 reading frame of pb1. this peptide derives from a novel conserved 87-residue protein, pb1-f2, which has several unusual features compared with other influenza gene products in addition to its mode of translation. these include its absence from some animal (particularly swine) influenza virus isolates, variable expressi ... | 2001 | 11726970 |
| the failure of the 1976 swine influenza immunization program. 1977. | | 2000 | 11765937 |
| tumor necrosis factor alpha exerts powerful anti-influenza virus effects in lung epithelial cells. | previous studies have associated influenza virus-induced expression of inflammatory cytokines, including tumor necrosis factor alpha (tnf-alpha), with influenza pathogenesis in the human respiratory tract and have suggested that alpha and beta interferons are the first cytokines recruited to counteract such infection. however, we report here that tnf-alpha has powerful anti-influenza virus activity. when infected with influenza virus, cultured porcine lung epithelial cells expressed tnf-alpha in ... | 2002 | 11773383 |
| emergence of influenza a viruses. | pandemic influenza in humans is a zoonotic disease caused by the transfer of influenza a viruses or virus gene segments from animal reservoirs. influenza a viruses have been isolated from avian and mammalian hosts, although the primary reservoirs are the aquatic bird populations of the world. in the aquatic birds, influenza is asymptomatic, and the viruses are in evolutionary stasis. the aquatic bird viruses do not replicate well in humans, and these viruses need to reassort or adapt in an inter ... | 2001 | 11779380 |
| integrating historical, clinical and molecular genetic data in order to explain the origin and virulence of the 1918 spanish influenza virus. | the spanish influenza pandemic of 1918-1919 caused acute illness in 25-30% of the world's population and resulted in the death of 40 million people. the complete genomic sequence of the 1918 influenza virus will be deduced using fixed and frozen tissues of 1918 influenza victims. sequence and phylogenetic analyses of the complete 1918 haemagglutinin (ha) and neuraminidase (na) genes show them to be the most avian-like of mammalian sequences and support the hypothesis that the pandemic virus cont ... | 2001 | 11779381 |
| h3n2 influenza viruses from domestic chickens in italy: an increasing role for chickens in the ecology of influenza? | in italy, multiple h3n2 influenza viruses were isolated from chickens with mild respiratory disease and were shown to replicate in the respiratory tracts of experimentally infected chickens; this finding is the first to show that h3n2 influenza viruses can replicate and cause disease in chickens. h3n2 influenza viruses in pigs on nearby farms seemed a likely source of the virus; however, antigenic and molecular analyses revealed that the gene segments of the viruses in chickens were mainly of eu ... | 2002 | 11807234 |
| synthesis and biological activity of the prodrug of class i major histocompatibility peptide gilgfvftl activated by beta-glucuronidase. | the first synthesis of a prodrug of hla-a2.1 associated antigenic influenza peptide 2a was accomplished. two methods for synthesis of prodrugs of antigenic peptides activated by beta-glucuronidase and comprising a self-immolative 3-nitrobenzyloxycarbonyl moiety were investigated. reaction of beta-glucuronic acid glycoside of 4-hydroxy-3-nitrobenzyl alcohol (3) with n,n'-disuccinimidyl carbonate (dsc) followed by conjugation with alaome, gly, thr, phe-leu, and leu-arg gave carbamates 4a-4f. deace ... | 2002 | 11831906 |
| viral and bacterial serology of free-ranging pacific walrus. | serum or heparinized plasma samples were obtained between 1994 and 1996 from 20 male and 20 female adult free-ranging pacific walrus (odobenus rosmarus divergens) from st. lawrence island and round island, alaska. samples were screened for antibodies to some potentially pathogenic bacteria and viruses. no sample had detectable antibody to brucella spp. three of 40 (8%) had low antibody titers to leptospira interrogans serovars. phocine distemper virus antibodies were not detected. serologic resp ... | 2002 | 11838234 |
| h5 avian and h9 swine influenza virus haemagglutinin structures: possible origin of influenza subtypes. | there are 15 subtypes of influenza a virus (h1-h15), all of which are found in avian species. three caused pandemics in the last century: h1 in 1918 (and 1977), h2 in 1957 and h3 in 1968. in 1997, an h5 avian virus and in 1999 an h9 virus caused outbreaks of respiratory disease in hong kong. we have determined the three-dimensional structures of the haemagglutinins (has) from h5 avian and h9 swine viruses closely related to the viruses isolated from humans in hong kong. we have compared them wit ... | 2002 | 11867515 |
| detection and subtyping of swine influenza h1n1, h1n2 and h3n2 viruses in clinical samples using two multiplex rt-pcr assays. | a total of 360 type a swine influenza virus-positive samples including cell culture isolates, nasal swabs or lung tissues along with 30 virus-negative samples were tested for the detection and subtyping of h1n1, h1n2 or h3n2 by two multiplex reverse transcription (rt)-pcr assays. the positive samples had been collected between 1999 and 2001 from pigs with respiratory diseases, and type a influenza virus was isolated and subtyped by hemagglutination inhibition (hi) test at the minnesota veterinar ... | 2002 | 11879692 |
| genetic characterization of h1n2 influenza a viruses isolated from pigs throughout the united states. | an h1n2 influenza a virus was isolated from a pig in the united states for the first time in 1999 (a. i. karasin, g. a. anderson, and c. w. olsen, j. clin. microbiol. 38:2453-2456, 2000). h1n2 viruses have been isolated subsequently from pigs in many states. phylogenetic analyses of eight such viruses isolated from pigs in indiana, illinois, minnesota, ohio, iowa, and north carolina during 2000 to 2001 showed that these viruses are all of the same reassortant genotype as that of the initial h1n2 ... | 2002 | 11880444 |
| antigenic and genetic diversity among swine influenza a h1n1 and h1n2 viruses in europe. | three subtypes of influenza a viruses, h1n1, h1n2 and h3n2, co-evolve in pigs in europe. h1n2 viruses isolated from pigs in france and italy since 1997 were closely related to the h1n2 viruses which emerged in the uk in 1994. in particular, the close relationship of the neuraminidases (nas) of these viruses to the na of a previous uk h3n2 swine virus indicated that they had not acquired the na from h3n2 swine viruses circulating in continental europe. moreover, antigenic and genetic heterogeneit ... | 2002 | 11907321 |
| origin and evolution of influenza virus hemagglutinin genes. | influenza a, b, and c viruses are the etiological agents of influenza. hemagglutinin (ha) is the major envelope glycoprotein of influenza a and b viruses, and hemagglutinin-esterase (he) in influenza c viruses is a protein homologous to ha. because influenza a virus pandemics in humans appear to occur when new subtypes of ha genes are introduced from aquatic birds that are known to be the natural reservoir of the viruses, an understanding of the origin and evolution of ha genes is of particular ... | 2002 | 11919291 |
| isolation from turkey breeder hens of a reassortant h1n2 influenza virus with swine, human, and avian lineage genes. | type a influenza viruses can infect a wide range of birds and mammals, but influenza in a particular species is usually considered to be species specific. however, infection of turkeys with swine h1n1 viruses has been documented on several occasions. this report documents the isolation of an h1n2 influenza virus from a turkey breeder flock with a sudden drop in egg production. sequence analysis of the virus showed that it was a complex reassortant virus with a mix of swine-, human-, and avian-or ... | 2002 | 11922322 |
| fatty acids on the a/ussr/77 influenza virus hemagglutinin facilitate the transition from hemifusion to fusion pore formation. | influenza virus hemagglutinin (ha) has three highly conserved acylation sites close to the carboxyl terminus of the ha2 subunit, one in the transmembrane domain and two in the cytoplasmic domain. each site is modified by palmitic acid through a thioester linkage to cysteine. to elucidate the biological significance of ha acylation, the acylation sites of ha of influenza virus strain a/ussr/77 (h1n1) were changed by site-directed mutagenesis, and the membrane fusion activity of mutant has lacking ... | 2002 | 11932425 |
| herd-level seroprevalence of swine-influenza virus in korea. | a total of 911 serum samples from 130 herds (an average of nine serum samples per herd) in korea were examined for antibody to swine h1n1-influenza virus using enzyme-linked immunosorbent assay (elisa). the list of farms was obtained from the korean swine association, and herds were included from all five of the country's states. farms were selected using a random-numbers table for swine within farms and for farms. all serum samples were collected from 22- to 24-week-old finishing pigs between s ... | 2002 | 11937238 |
| an immunoperoxidase monolayer assay for the detection of antibodies against swine influenza virus. | an immunoperoxidase monolayer assay (ipma) has been developed to detect antibodies against swine influenza a virus (siv) in pig sera. the test was evaluated by using sequential sera from pigs experimentally infected with h1n1 subtype of siv. two hundred field serum samples that had been examined by the hemagglutination inhibition (hi) test were also tested. antibodies specific to siv were detected as early as 3 days postinoculation (dpi) in the ipma test as compared with 7 dpi by the hi test. un ... | 2002 | 11939342 |
| comparison of embryonated chicken eggs with mdck cell culture for the isolation of swine influenza virus. | embryonated chicken eggs (ece) and the madin-darby canine kidney (mdck) cell line were compared for isolation of swine influenza virus (siv) from nasal swabs and tissue samples. samples originated from 30 pigs experimentally inoculated with 2 x 106 to 2 x 10(7) embryo infectious dose 50% (eid50)/ml of swine influenza strain a/swine/indiana/1726/88 (h1n1). the results were analyzed with mcnemar's chi-squared test for symmetry. the results indicated that more samples were siv-positive with ece tha ... | 2002 | 11989733 |
| detection of highly pathogenic and low pathogenic avian influenza subtype h5 (eurasian lineage) using nasba. | nucleic acid sequence-based amplification (nasba) is a technique that allows the rapid amplification of specific regions of nucleic acid obtained from a diverse range of sources. it is especially suitable for amplifying rna sequences. a nasba technique has been developed that allows the detection of avian influenza a subtype h5 from allantoic fluid harvested from inoculated chick embryos. the amplified viral rna is detected by electrochemiluminescence. the nasba technique described below is rapi ... | 2002 | 12008015 |
| the emergence of novel swine influenza viruses in north america. | since 1997, novel viruses of three different subtypes and five different genotypes have emerged as agents of influenza among pigs in north america. the appearance of these viruses is remarkable because there were no substantial changes in the overall epidemiology of swine influenza in the united states and canada for over 60 years prior to this time. viruses of the classical h1n1 lineage were virtually the exclusive cause of swine influenza from the time of their initial isolation in 1930 throug ... | 2002 | 12034486 |
| porcine surfactant protein d is n-glycosylated in its carbohydrate recognition domain and is assembled into differently charged oligomers. | surfactant protein d (sp-d) belongs to a subgroup of mammalian collagenous ca(2+)-dependent lectins known as the collectins. it is thought to play a significant role in the innate immune response against microorganisms within the lungs and at other mucosal surfaces. this report documents the isolation and characterization of sp-d purified from porcine lung lavage using mannan affinity chromatography and gel filtration. ultrastructural analysis shows both dodecameric and higher order oligomeric c ... | 2002 | 12034574 |
| avian influenza and human health. | natural infections with influenza a viruses have been reported in a variety of animal species including humans, pigs, horses, sea mammals, mustelids and birds. occasionally devastating pandemics occur in humans. although viruses of relatively few ha and na subtype combinations have been isolated from mammalian species, all 15 ha subtypes and all 9 na subtypes, in most combinations, have been isolated from birds. in the 20th century the sudden emergence of antigenically different strains transmis ... | 2002 | 12062786 |
| in vivo studies on cytokine involvement during acute viral respiratory disease of swine: troublesome but rewarding. | the early cytokines interferon-alpha (ifn-alpha), tumour necrosis factor-alpha (tnf-alpha), interleukin-1, -6 and -8 (il-1, -6, -8) are produced during the most early stage of an infection. the activities of these cytokines have been studied extensively in vitro and in rodents, but in vivo studies on the role of these cytokines in infectious diseases of food animals are few. this review concentrates on in vivo studies of cytokine involvement in infectious respiratory diseases of swine, with an e ... | 2002 | 12072230 |
| localization of swine influenza virus in naturally infected pigs. | swine influenza virus (siv) rna and antigen were detected in 15 naturally infected pigs by in situ hybridization using a nonradioactive digoxigenin-labeled cdna probe and by immunohistochemistry using an influenza virus h1n1-specific monoclonal antibody. a 582-base pair cdna probe for viral rna encoding the nucleocapsid protein of siv type a h1n1 strain was generated by the reverse transcription polymerase chain reaction. in situ hybridization and immunohistochemistry gave similar results for se ... | 2002 | 12102201 |
| the importance of animal influenza for human disease. | influenza is a zoonotic disease caused by a constantly varying rna virus resulting in a need for continuous surveillance to update human vaccines. our knowledge indicates that the intermittent pandemics of influenza originate from influenza viruses or gene segments from influenza viruses in lower animals and birds. these pandemics can be mild to catastrophic. while we have learned a great deal about the ecology and molecular properties of "animal" influenza viruses, we do not have a system for c ... | 2002 | 12110250 |
| h5n1 influenza in hong kong: virus characterizations. | in 1997, 18 people were infected in hong kong with an avian influenza a(h5n1) virus from chicken. this type of interspecies transmission was never detected before and could have resulted in the development of a pandemic strain. the occurrence suggests that the pig is not needed for the emergence of pandemic influenza virus strains. characteristics of the strains involved are discussed in relation to the question why, on the one hand, these strains were able to infect humans but on the other hand ... | 2002 | 12110266 |
| prevalence of swine influenza virus subtypes on swine farms in the united states. | serologic and virologic prevalence of infection with different swine influenza virus (siv) subtypes was investigated using swine sera, nasal swabs and lung samples that had been submitted for a diagnosis to the minnesota veterinary diagnostic laboratory. a total of 111,418 pig sera were tested for siv antibody between 1998 and 2000, and 25,348 sera (22.8%) were found to be positive by the hemagglutination inhibition (hi) test. of the positive samples, 16,807 (66.7%) and 8,541 (33.7%) had antibod ... | 2002 | 12111430 |
| vaccination of pigs with a dna construct expressing an influenza virus m2-nucleoprotein fusion protein exacerbates disease after challenge with influenza a virus. | in mice, vaccines inducing antibodies to the extracellular domain of the m2 protein (m2e) can confer protection to influenza a virus infection. unlike the surface glycoproteins, haemagglutinin and neuraminidase, this domain of m2 is highly conserved and is therefore a potential broad-spectrum immunogen. in this study, the protection conferred by vaccines inducing antibodies to m2e was evaluated in a challenge model for swine influenza in pigs. a protein resulting from the fusion between m2e and ... | 2002 | 12124449 |
| seroepidemiological evidence of avian h4, h5, and h9 influenza a virus transmission to pigs in southeastern china. | pig serum samples collected in southeastern china were examined for antibodies to influenza a viruses. since the hemagglutination inhibition (hi) test does not accurately detect antibodies to the hemagglutinins (has) of "avian" influenza viruses, we utilized the neutralization (nt) test to detect subtype-specific antibodies to the ha of avian viruses in pig sera. neutralizing antibodies to h1, h3, h4, and h5 influenza viruses were detected in the serum samples collected in 1977-1982 and 1998, su ... | 2002 | 12135631 |
| serologic evidence of h1 swine influenza virus infection in swine farm residents and employees. | we evaluated seropositivity to swine and human h1 influenza viruses in 74 swine farm owners, employees, their family members, and veterinarians in rural south-central wisconsin, compared with 114 urban milwaukee, wisconsin, residents. the number of swine farm participants with positive serum hemagglutination-inhibition (hi) antibody titers > or = 40 to swine influenza viruses (17/74) was significantly higher (p<0.001) than the number of seropositive urban control samples (1/114). the geometric m ... | 2002 | 12141967 |
| biological properties of n-acyl and n-haloacetyl neuraminic acids: processing by enzymes of sialic acid metabolism, and interaction with influenza virus. | several unnatural n-acyl neuraminic acids (n-propionyl, n-hexanoyl, n-benzoyl, n-trifluoroacetyl, n-chloroacetyl, n-difluoroacetyl) were prepared enzymatically using immobilised sialic acid aldolase. n-trifluoroacetyl-, n-chloroacetyl- and n-difluoroacetyl neuraminic acids were shown to enhance up to 10-fold the rate of association of influenza virus a to a sialoglycolipid neomembrane by surface plasmon resonance, and were found to act as weak inhibitors (k(iapp) 0.45-2.0 mm) of influenza virus ... | 2002 | 12150863 |
| phylogenetic analysis of h1n2 isolates of influenza a virus from pigs in the united states. | twenty-four h1n2 influenza a viruses were newly isolated from pigs in the united states. these isolates originated from 19 farms in 9 different swine producing states between 1999 and 2001. all farms had clinical histories of respiratory problem and/or abortion. the viral isolates were characterized genetically to determine the origin of all eight gene segments. the results showed that all h1n2 isolates were reassortants of classical swine h1n1 and triple reassortant h3n2 viruses. the neuraminid ... | 2002 | 12191781 |
| lethal h5n1 influenza viruses escape host anti-viral cytokine responses. | the h5n1 influenza viruses transmitted to humans in 1997 were highly virulent, but the mechanism of their virulence in humans is largely unknown. here we show that lethal h5n1 influenza viruses, unlike other human, avian and swine influenza viruses, are resistant to the antiviral effects of interferons and tumor necrosis factor alpha. the nonstructural (ns) gene of h5n1 viruses is associated with this resistance. pigs infected with recombinant human h1n1 influenza virus that carried the h5n1 ns ... | 2002 | 12195436 |
| drift in the nucleoprotein gene of swine influenza virus (h1n1) causing respiratory disease in pigs. | the nucleoprotein (np) gene of swine influenza h1n1 variant, a/sw/quebec/5393/91 (swqc91) was sequenced. when compared with other h1n1 strains, 12 amino acid (aa) replacements were observed in the 101-484 aa region of the np protein including two aas, 345 and 430, representing the unique lineage of swine viruses. phylogenetic analysis showed a drift in the np gene. | 2002 | 12206303 |
| antibodies to selected viral and bacterial pathogens in european wild boars from southcentral spain. | serum samples from 78 european wild boars (sus scrofa) harvested during the 1999-2000 hunting season were tested for antibodies to brucella spp., classical swine fever virus, erysipelothrix rhusiopathiae, haemophilus parasuis, leptospira interrogans serovar pomona, mycoplasma hyopneumoniae, pseudorabies virus (prv), porcine parvovirus (ppv), porcine reproductive and respiratory syndrome virus, salmonella serogroups b, c, and d, streptococcus suis, and swine influenza virus (siv) serotypes h1n1 a ... | 2002 | 12238391 |
| characterization of the 1918 "spanish" influenza virus matrix gene segment. | the coding region of influenza a virus rna segment 7 from the 1918 pandemic virus, consisting of the open reading frames of the two matrix genes m1 and m2, has been sequenced. while this segment is highly conserved among influenza virus strains, the 1918 sequence does not match any previously sequenced influenza virus strains. the 1918 sequence matches the consensus over the m1 rna-binding domains and nuclear localization signal and the highly conserved transmembrane domain of m2. amino acid cha ... | 2002 | 12368314 |
| recombinant adenovirus encoding the ha gene from swine h3n2 influenza virus partially protects mice from challenge with heterologous virus: a/hk/1/68 (h3n2). | immunization with recombinant adenoviral vaccine that induces potent immunity has been applied to many infectious diseases. we report here developing a recombinant adenoviral vaccine encoding the ha gene from swine h3n2 influenza virus (siv). two replication-defective recombinant adenoviruses were generated: (1) rad-ha: recombinant adenovirus encoding the ha gene from swine h3n2 influenza virus, and (2) rad-vector: a control recombinant adenovirus containing adenovirus and transfer plasmids with ... | 2002 | 12417948 |
| serological evidence of transmission of human influenza a and b viruses to caspian seals (phoca caspica). | seroepidemiological surveillance of influenza in caspian seals (phoca caspica) was conducted. antibodies to influenza a virus were detected in 54% (7/13), 57% (4/7), 40% (6/15) and 26% (11/42) of the serum samples collected in 1993, 1997, 1998 and 2000 by enzyme-linked immunosorbent assay (elisa). in an hemagglutination-inhibition (hi) test using h1-h15 reference influenza a viruses as antigens, more than half of the examined elisa-positive sera reacted with an h3n2 prototype strain a/aichi/2/68 ... | 2002 | 12437032 |
| correlations between lung proinflammatory cytokine levels, virus replication, and disease after swine influenza virus challenge of vaccination-immune pigs. | during experimental infection of pigs with swine influenza virus (siv), there is a strong temporal correlation between peak virus titers in the lungs, levels of different proinflammatory cytokines in bronchoalveolar lavage (bal) fluids, and disease. vaccination against siv can greatly reduce or prevent virus replication after challenge and the resulting disease. here, we took advantage of pigs from vaccination-challenge experiments, with different degrees of virological and clinical protection, ... | 2002 | 12513929 |
| influenza: prospect for prevention and control. | influenza is an emerging and re-emerging disease. since the late 1930s influenza viruses have been isolated yearly from different parts of the world during epidemics and pandemics. the "epidemiologic success" of influenza is due largely to rapid and unpredictable antigenic changes (antigenic drift) among human influenza viruses, and the emergence of new subtypes (antigenic shift), mostly from reassortment between human and avian influenza viruses. antigenic shifts were attributed to the global p ... | 2002 | 12515400 |
| [seroepidemiologic survey for a/pr/8/34 (h1n1) virus from chinese residents]. | a total of 414 serum specimens were collected from the residents with ages of < or = 20 year old in eight different parts of china for detecting antibody to a/pr/8/34(h1n1) influenza virus with hi test. of them, 24 had antibody with hi titers > or = 20 to a/pr/8/34(h1n1) virus. these 24 specimens were tested with the same method using a/swine/iowa/15/30 (h1n1), a/guangxi/10/94(h1n1) and a/beijing/53/97(h1n1) viruses. the results showed that except 5 of them had antibody with hi titers 20-40 to a ... | 1998 | 12526320 |
| genetic characterization of a porcine h1n2 influenza virus strain isolated in germany. | we examined selected influenza virus strains from various outbreaks of respiratory diseases among pigs in germany. besides h3n2 and h1n1 subtypes presently circulating in europe, an h1n2 influenza virus was isolated in 2000. sequence analysis of hemagglutinin, neuraminidase and matrix genes indicated that this virus is a reassortant of human h1n1 and human h3n2 strains with an internal gene, the m gene of avian origin. it is a result of a multiple reassortment event. | 2003 | 12566701 |
| [discovery of men infected by avian influenza a (h9n2) virus]. | to understand whether the avian influenza a(h9n2) virus can infect men or not. | 1999 | 12569771 |
| isolation of h3n2 swine influenza virus in south korea. | swine influenza is a significant respiratory disease causing occasional reproductive problems in naïve swine herds. although different subtypes of swine influenza virus (siv) have been implicated in clinical outbreaks of swine influenza in asian countries, no virus isolation has been made to identify siv of subtypes other than the h1n1 subtype in the korean swine population. in december 1998, an outbreak of acute respiratory disease was identified in a commercial swine farm located in the kyungg ... | 2003 | 12580292 |
| role of quail in the interspecies transmission of h9 influenza a viruses: molecular changes on ha that correspond to adaptation from ducks to chickens. | h9 influenza viruses have become endemic in land-based domestic poultry in asia and have sporadically crossed to pigs and humans. to understand the molecular determinants of their adaptation to land-based birds, we tested the replication and transmission of several 1970s duck h9 viruses in chickens and quail. quail were more susceptible than chickens to these viruses, and generation of recombinant h9 viruses by reverse genetics showed that changes in the ha gene are sufficient to initiate effici ... | 2003 | 12584339 |
| protection against a european h1n2 swine influenza virus in pigs previously infected with h1n1 and/or h3n2 subtypes. | a novel swine influenza virus, h1n2, circulates in european swine populations together with h1n1 and h3n2 viruses. this study examines whether post-infection immunity to h1n1 and/or h3n2 viruses provides cross-protection against h1n2 infection. pigs (n=51) were inoculated intranasally with either sw/belgium/1/98 (h1n1) or sw/flanders/1/98 (h3n2), or with both viruses at a 5-week interval. control groups were left uninoculated or inoculated with sw/gent/7625/99 (h1n2). four weeks later, all the p ... | 2003 | 12615433 |
| infectious disease. chasing the fickle swine flu. | | 2003 | 12624243 |
| effect of maternally derived antibodies on the clinical signs and immune response in pigs after primary and secondary infection with an influenza h1n1 virus. | the aim of this study was to determine the role of maternally derived antibodies (mda) against an influenza h1n1 virus in the clinical protection of piglets and especially their effect on the development of the active immunity after an infection with a homologous influenza h1n1 virus. twenty piglets with mda and 10 piglets without mda were housed together and inoculated twice with influenza h1n1 virus, at 7 and 15 weeks of age. nine piglets without mda were added to these groups at 12 weeks of a ... | 2003 | 12628761 |
| detection rates of porcine reproductive and respiratory syndrome virus, porcine circovirus type 2, and swine influenza virus in porcine proliferative and necrotizing pneumonia. | a retrospective study on pig lung tissues from 60 cases of proliferative and necrotizing pneumonia (pnp) was performed to determine the presence of porcine reproductive and respiratory syndrome virus (prrsv), swine influenza virus (siv), and porcine circovirus type 2 (pcv2) in these lesions. cases selected included 30 cases diagnosed between 1988 and 1992 and 30 cases diagnosed between 1997 and 2001. in each group of 30 cases, 10 were from suckling piglets, whereas the other 20 were from postwea ... | 2003 | 12637753 |
| human infection by a swine influenza a (h1n1) virus in switzerland. | the isolation of a/switzerland/8808/2002 provides further evidence of sporadic human infection by contemporary swine influenza a h1n1 viruses, antigenically and genetically distinct from h1n1 viruses circulating in the human population. together with the recent emergence of human-swine-avian reassortant viruses in pig populations in europe and north america, frequent transmission between swine and human populations emphasises the potential for the emergence in pigs of novel subtypes with the cap ... | 2003 | 12664301 |
| [a novel test for diagnosis of influenza]. | to set up a novel, simple, sensitive, specific, repeatable and rapid assay for diagnosis of influenza. | 2002 | 12665920 |
| a novel influenza a virus activating enzyme from porcine lung: purification and characterization. | proteolytic activation of hemagglutinin, an envelope glycoprotein of the influenza virus, by host proteases is essential for infection and proliferation of the virus. however, there is no well-defined, inherent source of host proteases in man or swine, both of which are natural hosts for human influenza viruses. we have recently isolated a 32 kda protein in a high salt extract from porcine lungs, which possess the hemagglutinin processing activity. in this study, we attempted to purify another h ... | 2003 | 12675514 |
| evaluation of a multiplex reverse transcription-polymerase chain reaction assay for subtyping hemagglutinin genes 1 and 3 of swine influenza type a virus in clinical samples. | a multiplex reverse transcription-polymerase chain reaction (rt-pcr) assay was developed to detect and identify subtypes of hemagglutinin (h) 1 and h3 swine influenza virus (siv). two oligonucleotide primer sets were prepared using published sequence data for h1n1 and h3n2. the pcr products with unique size characteristics of each subtype were sequenced, and the sequences were confirmed to be subtype specific for h gene 1 or 3. these primer sets did not amplify when rt-pcr assay was performed fo ... | 2002 | 12680647 |
| characterization of a swine-like reassortant h1n2 influenza virus isolated from a wild duck in the united states. | an h1n2 influenza virus (a/duck/north carolina/91347/01) (dk/nc) was isolated from a wild duck in the united states in 2001. genetic analyses showed that this duck virus has the same human/classical swine/avian reassortant genotype as the h1n2 viruses that have been isolated from pigs and turkeys in the us since 1999. phylogenetic analyses of each gene segment further confirmed that the dk/nc virus is closely related to the domestic animal h1n2 isolates. in particular, dk/nc is most closely rela ... | 2003 | 12727349 |
| infectious diseases. avian flu outbreak sets off alarm bells. | | 2003 | 12730565 |
| comparison of the pathogenesis of two genetically different h3n2 influenza a viruses in pigs. | in 1997 and 1998, h3n2 influenza a viruses emerged among pigs in north america. genetic analyses of the h3n2 isolates demonstrated that they had distinctly different genotypes. the most commonly isolated viruses in the united states have a triple-reassortant genotype, with the hemagglutinin, neuraminidase, and pb1 polymerase genes being of human influenza virus origin, the nucleoprotein, matrix, and nonstructural genes being of classical swine influenza virus origin, and the pa and pb2 polymeras ... | 2003 | 12734230 |
| characterization of h9 subtype influenza viruses from the ducks of southern china: a candidate for the next influenza pandemic in humans? | a current view of the emergence of pandemic influenza viruses envisages a gene flow from the aquatic avian reservoir to humans via reassortment in pigs, the hypothetical "mixing vessel." understanding arising from recent h5n1 influenza outbreaks in hong kong since 1997 and the isolation of avian h9n2 virus from humans raises alternative options for the emergence of a new pandemic virus. here we report that h9n2 influenza viruses established in terrestrial poultry in southern china are transmitte ... | 2003 | 12768017 |
| replication and transmission of influenza viruses in japanese quail. | quail have emerged as a potential intermediate host in the spread of avian influenza a viruses in poultry in hong kong. to better understand this possible role, we tested the replication and transmission in quail of influenza a viruses of all 15 ha subtypes. quail supported the replication of at least 14 subtypes. influenza a viruses replicated predominantly in the respiratory tract. transmission experiments suggested that perpetuation of avian influenza viruses in quail requires adaptation. swi ... | 2003 | 12788625 |
| pathogenic and antigenic properties of phylogenetically distinct reassortant h3n2 swine influenza viruses cocirculating in the united states. | swine influenza is an acute respiratory disease caused by type a influenza viruses. before 1998, swine influenza virus isolates in the united states were mainly of the classical h1n1 lineage. since then, phylogenetically distinct reassortant h3n2 viruses have been identified as respiratory pathogens in pigs on u.s. farms. the h3n2 viruses presently circulating in the u.s. swine population are triple reassortants containing avian-like (pa and pb2), swine-like (m, np, and ns), and human-like (ha, ... | 2003 | 12843064 |
| porcine pulmonary collectins show distinct interactions with influenza a viruses: role of the n-linked oligosaccharides in the carbohydrate recognition domain. | influenza a virus (iav) infections are a major cause of respiratory disease of humans and animals. pigs can serve as important intermediate hosts for transmission of avian iav strains to humans, and for the generation of reassortant strains; this may result in the appearance of new pandemic iav strains in humans. we have studied the role of the porcine lung collectins surfactant proteins d and a (psp-d and psp-a), two important components of the innate immune response against iav. hemagglutinati ... | 2003 | 12874235 |
| investigations of the efficacy of european h1n1- and h3n2-based swine influenza vaccines against the novel h1n2 subtype. | the efficacy of a commercial swine influenza vaccine based on a/new jersey/8/76 (h1n1) and a/port chalmers/1/73 (h3n2) strains was tested against challenge with an h1n2 swine influenza virus. influenza virus-seronegative pigs were vaccinated twice with the vaccine when they were four and eight weeks old, or with the same vaccine supplemented with an h1n2 component. control pigs were left unvaccinated. three weeks after the second vaccination, all the pigs were challenged intratracheally with the ... | 2003 | 12877210 |
| [fowl plague: a potential danger also for humans]. | | 2003 | 12892059 |
| the origin of the 1918 pandemic influenza virus: a continuing enigma. | influenza a virus is a major public health threat, killing more than 30,000 per year in the usa alone, sickening millions and inflicting substantial economic costs. novel influenza virus strains emerge periodically to which humans have little immunity, resulting in devastating pandemics. the 1918 pandemic killed nearly 700,000 americans and 40 million people worldwide. pandemics in 1957 and 1968, while much less devastating than 1918, also caused tens of thousands of deaths in the usa. the influ ... | 2003 | 12917448 |
| retrospective analysis of etiologic agents associated with respiratory diseases in pigs. | twenty-eight hundred and seventy-two cases of respiratory disease in pigs were analyzed for their etiologic agents. two or more pathogens were detected from 88.2% of the cases, indicating that porcine reproductive and respiratory syndrome virus (prrsv) or swine influenza virus (siv) combined with other bacterial agents was a common cause for porcine respiratory diseases in the mid-western usa. | 2003 | 14524628 |
| new h1n2 and h3n1 influenza viruses in taiwanese pig herds. | | 2003 | 14567672 |
| inhibition of influenza a virus sialidase activity by sulfatide. | sulfatide, which binds to influenza a viruses and prevents the viral infection, was found to inhibit the sialidase activities of influenza a viruses in a ph-dependent manner. the kinetic parameters of the effect of sulfatide on the sialidase activities of human influenza a viruses using fluorometric assay indicated that sulfatide was a powerful and non-competitive type inhibitor in low-ph conditions. | 2003 | 14572650 |
| update on molecular epidemiology of h1, h5, and h7 influenza virus infections in poultry in north america. | avian influenza is endemic in wild birds in north america, and the virus routinely has been transmitted from this reservoir to poultry. influenza, once introduced into poultry, can become endemic within the poultry population. it may be successfully eradicated by human intervention, or the virus may fail to successfully spread on its own. in the last 5 yr, influenza virus has been isolated from poultry in the united states on numerous occasions, and, with the use of molecular epidemiology, the r ... | 2003 | 14575082 |
| land-based birds as potential disseminators of avian mammalian reassortant influenza a viruses. | chickens, quail, and other land-based birds are extensively farmed around the world. they have been recently implicated in zoonotic outbreaks of avian influenza in hong kong. the possibility that land-based birds could act as mixing vessels or disseminators of avian/mammalian reassortant influenza a viruses with pandemic potential has not been evaluated. in this report, we investigated whether chickens and japanese quail are susceptible to a mammalian influenza virus (a/swine/texas/4199-2/98 [h3 ... | 2003 | 14575124 |
| generation and characterization of an h9n2 cold-adapted reassortant as a vaccine candidate. | h9n2 subtype avian influenza viruses have been identified in avian species worldwide, and infections in pigs were confirmed in hong kong in 1998. subsequently, h9n2 viruses were isolated from two children in hong kong in 1999, and five human infections were reported from china, raising the possibility that h9n2 viruses pose a potential pandemic threat for humans. these events prompted us to develop a vaccine candidate to protect humans against this subtype of influenza a viruses. reassortant h1n ... | 2003 | 14575127 |