| structural changes associated with type-a influenza in mallard duck tracheal organ culture. | mallard duck tracheal organ cultures were used to study structural changes associated with infection with type-a influenza (a/turkey/wis/68) (h9n2) at the light-microscope and electron-microscope levels. light-microscope changes in infected organ culture were cytoplasmic vacuolization, nuclear swelling, reduction in ciliated epithelium, and sloughing of epithelial cells. ultrastructural changes included the loss of cilia and microvilli, distortion and swelling of cellular organelles, breakdown o ... | 1978 | 697664 |
| a broad-spectrum avian influenza subtype antigen for indirect enzyme-linked immunosorbent assay. | a broad-spectrum viral antigen for the detection of avian-influenza-virus-specific antibodies, using the indirect enzyme-linked immunosorbent assay (elisa), was identified. purified and disrupted antigens were used, which helped to increase the sensitivity of the assay. all of the antigens tested were able to detect antibodies to homologous and heterologous viruses to varying degrees. the h9n2 antigen was the best single antigen to use in the elisa to screen for avian influenza virus antibodies. ... | 1989 | 2751558 |
| molecular characterization of h9n2 influenza viruses: were they the donors of the "internal" genes of h5n1 viruses in hong kong? | the origin of the h5n1 influenza viruses that killed six of eighteen infected humans in 1997 and were highly pathogenic in chickens has not been resolved. these h5n1 viruses transmitted directly to humans from infected poultry. in the poultry markets in hong kong, both h5n1 and h9n2 influenza viruses were cocirculating, raising the possibility of genetic reassortment. here we analyze the antigenic and genetic features of h9n2 influenza viruses with different epidemiological backgrounds. the resu ... | 1999 | 10430948 |
| human infection with influenza h9n2. | we report the clinical features of two cases of human infection with influenza a virus subtype h9n2 in hong kong, and show that serum samples from blood donors in hong kong had neutralising antibody suggestive of prior infection with influenza h9n2. | 1999 | 10489954 |
| 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 |
| global epidemiology of influenza: past and present. | pandemics are the most dramatic presentation of influenza. three have occurred in the twentieth century: the 1918 h1n1 pandemic, the 1957 h2n2 pandemic, and the 1968 h3n2 pandemic. the tools of molecular epidemiology have been applied in an attempt to determine the origin of pandemic viruses and to understand what made them such successful pathogens. an excellent example of this avenue of research is the recent phylogenetic analysis of genes of the virus that caused the devastating 1918 pandemic ... | 2000 | 10774473 |
| 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 |
| 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 |
| continued circulation in china of highly pathogenic avian influenza viruses encoding the hemagglutinin gene associated with the 1997 h5n1 outbreak in poultry and humans. | since the outbreak in humans of an h5n1 avian influenza virus in hong kong in 1997, poultry entering the live-bird markets of hong kong have been closely monitored for infection with avian influenza. in march 1999, this monitoring system detected geese that were serologically positive for h5n1 avian influenza virus, but the birds were marketed before they could be sampled for virus. however, viral isolates were obtained by swabbing the cages that housed the geese. these samples, known collective ... | 2000 | 10864673 |
| a simple restriction fragment length polymorphism-based strategy that can distinguish the internal genes of human h1n1, h3n2, and h5n1 influenza a viruses. | a simple molecular technique for rapid genotyping was developed to monitor the internal gene composition of currently circulating influenza a viruses. sequence information from recent h1n1, h3n2, and h5n1 human virus isolates was used to identify conserved regions within each internal gene, and gene-specific pcr primers capable of amplifying all three virus subtypes were designed. subtyping was based on subtype-specific restriction fragment length polymorphism (rflp) patterns within the amplifie ... | 2000 | 10878047 |
| avian-to-human transmission of h9n2 subtype influenza a viruses: relationship between h9n2 and h5n1 human isolates. | in 1997, 18 cases of influenza in hong kong (bird flu) caused by a novel h5n1 (chicken) virus resulted in the deaths of six individuals and once again raised the specter of a potentially devastating influenza pandemic. slaughter of the poultry in the live bird markets removed the source of infection and no further human cases of h5n1 infection have occurred. in march 1999, however, a new pandemic threat appeared when influenza a h9n2 viruses infected two children in hong kong. these two virus is ... | 2000 | 10920197 |
| h9n2 influenza viruses possessing h5n1-like internal genomes continue to circulate in poultry in southeastern china. | the transmission of h9n2 influenza viruses to humans and the realization that the a/hong kong/156/97-like (h5n1) (abbreviated hk/156/97) genome complex may be present in h9n2 viruses in southeastern china necessitated a study of the distribution and characterization of h9n2 viruses in poultry in the hong kong sar in 1999. serological studies indicated that h9n2 influenza viruses had infected a high proportion of chickens and other land-based birds (pigeon, pheasant, quail, guinea fowl, and chukk ... | 2000 | 11000205 |
| sequence analysis of the hemagglutinin gene of h9n2 korean avian influenza viruses and assessment of the pathogenic potential of isolate ms96. | sequence analysis of the hemagglutinin (ha) gene of five korean h9n2 avian influenza virus (aiv) isolates showed that these viruses were closely related and possibly came from the same source. phylogenetic analysis of the ha1 subunit of h9 subtype isolates revealed that korean aiv isolates were different from isolates from the poultry markets in hong kong in 1997. none of the korean aivs had multiple basic amino acids at the ha cleavage site that confer high pathogenicity to some h5 and h7 aivs. ... | 2000 | 11006999 |
| molecular aspects of avian influenza (h5n1) viruses isolated from humans. | in 1997, 18 human infections with h5n1 influenza type a were identified in hong kong and six of the patients died. there were concomitant outbreaks of h5n1 infections in poultry. the gene segments of the human h5n1 viruses were derived from avian influenza a viruses and not from circulating human influenza a viruses. in 1999 two cases of human infections caused by avian h9n2 virus were also identified in hong kong. these events established that avian influenza viruses can infect humans without p ... | 2000 | 11015744 |
| heterologous protection against lethal a/hongkong/156/97 (h5n1) influenza virus infection in c57bl/6 mice. | the continual threat posed by newly emerging influenza virus strains is demonstrated by the recent outbreak of h5n1 influenza virus in hong kong. currently, immunization against influenza virus infection is fairly adequate, but it is imperative that improved vaccines are developed that can protect against a variety of strains and be generated rapidly. since humoral immunity is ineffective against serologically distinct viruses, one strategy would be to develop vaccines that emphasize cellular im ... | 2000 | 11038381 |
| h9n2 subtype influenza a viruses in poultry in pakistan are closely related to the h9n2 viruses responsible for human infection in hong kong. | following the outbreak of h5n1 "bird flu" in hong kong in 1997, the isolation of h9n2 subtype viruses from patients in southern china and hong kong sar once again raised the spectre of a possible influenza pandemic. h9n2 viruses have recently been responsible for disease in poultry in various parts of the world and preliminary studies of the h9 haemagglutinin (ha) genes of viruses isolated during 1998 and 1999 in germany, iran, pakistan, and saudi arabia showed a close relationship to the ha gen ... | 2000 | 11112478 |
| the neuraminidase inhibitor gs4104 (oseltamivir phosphate) is efficacious against a/hong kong/156/97 (h5n1) and a/hong kong/1074/99 (h9n2) influenza viruses. | in 1997, an h5n1 avian influenza a/hong kong/156/97 virus transmitted directly to humans and killed six of the 18 people infected. in 1999, another avian a/hong/1074/99 (h9n2) virus caused influenza in two children. in such cases in which vaccines are unavailable, antiviral drugs are crucial for prophylaxis and therapy. here we demonstrate the efficacy of the neuraminidase inhibitor gs4104 (oseltamivir phosphate) against these h5n1 and h9n2 viruses. gs4071 (the active metabolite of oseltamivir) ... | 2000 | 11114412 |
| avian influenza viruses infecting humans. | avian species, particularly waterfowl, are the natural hosts of influenza a viruses. influenza viruses bearing each of the 15 hemagglutinin and nine neuraminidase subtypes infect birds and serve as a reservoir from which influenza viruses or genes are introduced into the human population. viruses with novel hemagglutinin genes derived from avian influenza viruses, with or without other accompanying avian influenza virus genes, have the potential for pandemic spread when the human population lack ... | 2000 | 11130181 |
| pandemic threat posed by avian influenza a viruses. | influenza pandemics, defined as global outbreaks of the disease due to viruses with new antigenic subtypes, have exacted high death tolls from human populations. the last two pandemics were caused by hybrid viruses, or reassortants, that harbored a combination of avian and human viral genes. avian influenza viruses are therefore key contributors to the emergence of human influenza pandemics. in 1997, an h5n1 influenza virus was directly transmitted from birds in live poultry markets in hong kong ... | 2001 | 11148006 |
| 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 |
| cross-reactive, cell-mediated immunity and protection of chickens from lethal h5n1 influenza virus infection in hong kong poultry markets. | in 1997, avian h5n1 influenza virus transmitted from chickens to humans resulted in 18 confirmed infections. despite harboring lethal h5n1 influenza viruses, most chickens in the hong kong poultry markets showed no disease signs. at this time, h9n2 influenza viruses were cocirculating in the markets. we investigated the role of h9n2 influenza viruses in protecting chickens from lethal h5n1 influenza virus infections. sera from chickens infected with an h9n2 influenza virus did not cross-react wi ... | 2001 | 11222674 |
| imported parakeets harbor h9n2 influenza a viruses that are genetically closely related to those transmitted to humans in hong kong. | in 1997 and 1998, h9n2 influenza a viruses were isolated from the respiratory organs of indian ring-necked parakeets (psittacula krameri manillensis) that had been imported from pakistan to japan. the two isolates were closely related to each other (>99% as determined by nucleotide analysis of eight rna segments), indicating that h9n2 viruses of the same lineage were maintained in these birds for at least 1 year. the hemagglutinins and neuraminidases of both isolates showed >97% nucleotide ident ... | 2001 | 11238878 |
| efficacy of zanamivir against avian influenza a viruses that possess genes encoding h5n1 internal proteins and are pathogenic in mammals. | in 1997, an avian h5n1 influenza virus, a/hong kong/156/97 (a/hk/156/97), caused six deaths in hong kong, and in 1999, an avian h9n2 influenza virus infected two children in hong kong. these viruses and a third avian virus [a/teal/hk/w312/97 (h6n1)] have six highly related genes encoding internal proteins. additionally, a/chicken/hk/g9/97 (h9n2) virus has pb1 and pb2 genes that are highly related to those of a/hk/156/97 (h5n1), a/teal/hk/w312/97 (h6n1), and a/quail/hk/g1/97 (h9n2) viruses. becau ... | 2001 | 11257037 |
| h9n2 influenza a viruses from poultry in asia have human virus-like receptor specificity. | h9n2 influenza a viruses are currently widespread in chickens, quail, and other poultry in asia and have caused a few cases of influenza in humans. in this study, we found that h9n2 viruses from hong kong live bird markets have receptor specificity similar to that of human h3n2 viruses. in addition, the neuraminidase of poultry h9n2 viruses has mutations in its hemadsorbing site, a characteristic resembling that of human h2n2 and h3n2 viruses but differing from that of other avian viruses. pecul ... | 2001 | 11277689 |
| immunity to influenza a h9n2 viruses induced by infection and vaccination. | avian influenza a h9n2 viruses are widespread among domestic poultry and were recently isolated from humans with respiratory illness in china. two antigenically and genetically distinct groups of h9n2 viruses (g1 and g9) are prevalent in china. to evaluate a strategy for vaccination, we compared g1 and g9 viruses for their relative immunogenicity and cross-protective efficacy. infection of balb/c mice with representative viruses of either group protected against subsequent challenge with the hom ... | 2001 | 11312361 |
| [a strain of influenza a h9n2 virus repeatedly isolated from human population in china]. | to understand the subtype of surface proteins (hemagglutinin and neuraminidase) and antigenic character of the isolate of influenza virus, as well as to know its origin. | 2000 | 11498680 |
| detection of influenza a subtypes in community-based surveillance. | a rapid microtitre cell enzyme immuno assay (cell-eia) was developed for the detection of influenza a subtypes in nasopharyngeal(nps) swabs taken for surveillance. during the 1997/1998 influenza season in the united kingdom, cell-eia was compared to cell culture for the detection and typing of influenza a viruses in nps obtained by sentinel general practitioners in community surveillance. the cell eia can also be used to detect different influenza a subtypes (h3n2, h1n1, h5n3, h5n1, h7n7, and h9 ... | 2001 | 11505459 |
| comparison of efficacies of rwj-270201, zanamivir, and oseltamivir against h5n1, h9n2, and other avian influenza viruses. | the orally administered neuraminidase (na) inhibitor rwj-270201 was tested in parallel with zanamivir and oseltamivir against a panel of avian influenza viruses for inhibition of na activity and replication in tissue culture. the agents were then tested for protection of mice against lethal h5n1 and h9n2 virus infection. in vitro, rwj-270201 was highly effective against all nine na subtypes. na inhibition by rwj-270201 (50% inhibitory concentration, 0.9 to 4.3 nm) was superior to that by zanamiv ... | 2001 | 11557461 |
| 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 |
| characterization of a human h9n2 influenza virus isolated in hong kong. | two h9n2 viruses were isolated, for the first time, from humans in hong kong in 1999. isolation of influenza viruses with a novel subtype of the hemagglutinin (ha) drew attention of health care authorities worldwide from the view of pandemic preparedness. sequence analysis of the ha genes reveals that ha of a/hong kong/1073/99 (h9n2) is most closely related to that of a/quail/hk/g1/97 (h9n2) that contains the internal genes similar to those of hong kong/97 (h5n1) viruses. phylogenetic and antige ... | 2001 | 11567756 |
| 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 |
| amino acids responsible for the absolute sialidase activity of the influenza a virus neuraminidase: relationship to growth in the duck intestine. | the 1957 human pandemic strain of influenza a virus contained an avian virus hemagglutinin (ha) and neuraminidase (na), both of which acquired specificity for the human receptor, n-acetylneuraminic acid linked to galactose of cellular glycoconjugates via an alpha2-6 bond (neuacalpha2-6gal). although the na retained considerable specificity for neuacalpha2-3gal, its original substrate in ducks, it lost the ability to support viral growth in the duck intestine, suggesting a growth-restrictive chan ... | 2001 | 11689658 |
| characterization of h5n1 influenza viruses that continue to circulate in geese in southeastern china. | the h5n1 influenza virus, which killed humans and poultry in 1997, was a reassortant that possibly arose in one type of domestic poultry present in the live-poultry markets of hong kong. given that all the precursors of h5n1/97 are still circulating in poultry in southern china, the reassortment event that generated h5n1 could be repeated. because a/goose/guangdong/1/96-like (h5n1; go/gd) viruses are the proposed donors of the hemagglutinin gene of the h5n1 virus, we investigated the continued c ... | 2002 | 11739677 |
| molecular changes associated with the transmission of avian influenza a h5n1 and h9n2 viruses to humans. | in order to identify molecular changes associated with the transmission of avian influenza a h5n1 and h9n2 viruses to humans, the internal genes from these viruses were compared to sequences from other avian and human influenza a isolates. phylogenetically, each of the internal genes of all sixteen of the human h5n1 and both of the h9n2 isolates were closely related to one another and fell into a distinct clade separate from clades formed by the same genes of other avian and human viruses. all s ... | 2002 | 11748666 |
| molecular evolution of h6 influenza viruses from poultry in southeastern china: prevalence of h6n1 influenza viruses possessing seven a/hong kong/156/97 (h5n1)-like genes in poultry. | the a/teal/hong kong/w312/97 (h6n1) influenza virus and the human h5n1 and h9n2 influenza viruses possess similar genes encoding internal proteins, suggesting that h6n1 viruses could become novel human pathogens. the molecular epidemiology and evolution of h6 influenza viruses were characterized by antigenic and genetic analyses of 29 h6 influenza viruses isolated from 1975 to 1981 and 1997 to 2000. two distinct groups were identified on the basis of their antigenic characteristics. phylogenetic ... | 2002 | 11752141 |
| 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 |
| characterization of hemagglutinin gene of influenza a virus subtype h9n2. | to determine the origin of human influenza a (h9n2) virus and the relationship among h9n2 strains isolated from different hosts, on the basis of molecular biology. | 2001 | 11779442 |
| 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 |
| protective cross-reactive cellular immunity to lethal a/goose/guangdong/1/96-like h5n1 influenza virus is correlated with the proportion of pulmonary cd8(+) t cells expressing gamma interferon. | a/goose/guangdong/1/96-like h5n1 influenza viruses now circulating in southeastern china differ genetically from the h5n1 viruses transmitted to humans in 1997 but were their precursors. here we show that the currently circulating h9n2 influenza viruses provide chickens with cross-reactive protective immunity against the currently circulating h5n1 influenza viruses and that this protective immunity is closely related to the percentage of pulmonary cd8(+) t cells expressing gamma interferon (ifn- ... | 2002 | 11967305 |
| evaluation of the directigen flua+b test for rapid diagnosis of influenza virus type a and b infections. | directigen flua+b (bd diagnostic systems, sparks, md.), a new rapid test for the detection of influenza virus types a and b, was evaluated with nasopharyngeal aspirate specimens collected from 250 patients in comparison with culture and direct fluorescent antigen (dfa) detection tests. the patients studied were predominantly children, 80% being </=6 years old. specimens negative by culture but positive by the directigen flua+b or dfa tests were analyzed by reverse transcription-pcr to resolve th ... | 2002 | 11980941 |
| analysis of the 1991-2000 influenza epidemic in guangdong province, china. | influenza surveillance networks in guangdong were established to investigate the epidemiological characteristics of influenza and influenza epidemics. influenza activity peaked annually from march to july in guangdong in 1991-2000; influenza h3n2 predominated in the epidemic (7 years of 10); the outbreak of influenza in 1996 was the remarkable result of antigenic drift of h3n2 strain. ten isolates of h9n2 strains were discovered from human subjects in 1998 and 1999: chicken strains isolated afte ... | 2001 | 12041555 |
| 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 |
| [differences in receptor specificity between the influenza a viruses isolated from the duck, chicken, and human]. | the affinity of the duck, chicken, and human influenza viruses to the host cell sialosides was determined, and considerable distinctions between duck and chicken viruses were found. duck viruses bind to a wide range of sialosides, including the short-stem gangliosides. most of the chicken viruses, like human ones, lose the ability to bind these gangliosides, which strictly correlates with the appearance of carbohydrate at position 158-160. the affinity of the chicken viruses to sialoglycoconjuga ... | 2002 | 12068641 |
| the continued pandemic threat posed by avian influenza viruses in hong kong. | in 1997, a highly pathogenic avian h5n1 influenza virus was transmitted directly from live commercial poultry to humans in hong kong. of the 18 people infected, six died. the molecular basis for the high virulence of this virus in mice was found to involve an amino acid change in the pb2 protein. to eliminate the source of the pathogenic virus, all birds in the hong kong markets were slaughtered. in 1999, another avian influenza virus of h9n2 subtype was transmitted to two children in hong kong. ... | 2002 | 12110213 |
| influenza activity in china: 1998-1999. | during 1989-1999, influenza a h3n2 and h1n1 subtypes and b type viruses were still co-circulating in human population in china, while influenza a (h3n2) virus was predominant strain. the two antigenically and genetically distinguishable strains of influenza b virus were also still co-circulating in men in southern china. the antigenic analysis indicated that most of the h3n2 viruses were a/panama/2007/99 (h3n2)-like strain, the most of the h1n1 viruses were antigenically similar to a/beijing/262 ... | 2002 | 12110253 |
| differences between influenza virus receptors on target cells of duck and chicken. | h5, h7, and h9 subtype influenza viruses in land-based poultry often differ from viruses of wild aquatic birds by deletions in the stalk of the neuraminidase, by the presence of additional carbohydrates on the hemagglutinin, and by occasional changes in the receptor specificity. to test whether these differences could reflect distinctions between the virus receptors in different avian species, we compared the binding of duck, chicken and human influenza viruses to cell membranes and gangliosides ... | 2002 | 12111429 |
| 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 |
| eight-plasmid system for rapid generation of influenza virus vaccines. | the antigenic variation of influenza a virus hemagglutinin (ha) and neuraminidase (na) glycoproteins requires frequent changes in vaccine formulation. the classical method of creating influenza virus seed strains for vaccine production is to generate 6 + 2 reassortants that contain six genes from a high-yield virus, such as a/pr/8/34 (h1n1) and the ha and na genes of the circulating strains. the techniques currently used are time-consuming because of the selection process required to isolate the ... | 2002 | 12163268 |
| [characterization of genome of a/guangzhou/333/99(h9n2) virus]. | to understand the characterization of genome of a strain of avian influenza a h9n2 virus repeatedly isolated from a child with influenza illness. thereafter to reveal the origin of this h9n2 virus. | 2002 | 12196825 |
| natural cases and an experimental study of h9n2 avian influenza in commercial broiler chickens of iran. | since 1998, an epidemic of avian influenza has occurred in the iranian poultry industry. the agent was pathotyped as non-highly pathogenic and subtyped as an h9n2 avian influenza virus. therefore it did not require eradication. however, frequent incidences of high mortality were observed commonly on broiler farms. no other species of bird were affected. the circulation of the virus and mixed infection with other respiratory pathogens, particularly infectious bronchitis virus and mycoplasma galli ... | 2002 | 12396348 |
| pandemic preparedness: lessons learnt from h2n2 and h9n2 candidate vaccines. | vaccination against influenza is considered to be one of the key interventions in case of a pandemic. unfortunately, shortages in vaccine supplies will occur because of the substantial increase in vaccine demands worldwide and the limited available supply resources. the recommended use of monovalent--instead of current trivalent--vaccines containing 15 micro g hemagglutinin (ha) per dose can theoretically triple vaccine volumes but is unlikely to meet the demand. furthermore, previous experience ... | 2002 | 12458361 |
| 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 |
| [comparison of sequences of the hemagglutinin gene and phylogenetical analysis of h9 subtype avian influenza viruses isolated from some regions in china]. | in order to explore the genetic mutaions of the hemagglutinin(ha) gene and the law of molecular epidemiology of h9 subtype avian influenza viruses in china, 23 h9 subtype avian influenza viruses(aivs) were isolated from 12 provinces of china in recent years. their nucleotide sequences of cdna of ha gene were determined by rt-pcr and sequencing. their nucleotide and putaive amino acid sequences homology was compared. the results showed that their nucleotide sequence homology was from 94.1% to 100 ... | 2002 | 12557368 |
| [recombinant fowlpox virus expressing ha from subtype h9n2 of avian influenza virus and its protective immunity against homologous challenge in chickens]. | the hemagglutinin (ha) gene from the aiv, a/chicken/china/f/1998(h9n2), was amplified with the rt-pcr technique and directionally inserted into transferring vector 1175, resulted in recombinant transferring vector 1175ha. in order to generate recombinant fowlpox virus expressing ha(rfpv-ha), the recombinant transferring vector 1175ha was used to transfect the chicken embryo fibroblasts(cef) pre-infected with wide type fowlpox virus. then, by selection of blue plaques on the cef overlaid with aga ... | 2002 | 12557550 |
| [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 |
| the influenza virus gene pool in a poultry market in south central china. | we surveyed influenza activity in a live poultry market in central china for 16 months, isolating viruses from 1% of 6360 fecal samples. we obtained multiple h3n6, h9n2, h2n9, h3n3, and h4n6 isolates and single h1n1 and h3n2 isolates. two distinct h3 molecules were identified; other hemagglutinin subtypes were phylogenetically homogeneous. the h3n6 viruses (9 genotypes) and h9n2 viruses (4 genotypes) were genetically heterogeneous, whereas the h2n9, h3n3 and h4n6 viruses had single genotypes. th ... | 2003 | 12573572 |
| [virological and serological surveys for h9n2 subtype of influenza a virus in chickens and men in shenzhen city]. | to understand the distribution of influenza a h9n2 virus in chickens and men in shenzhen area. | 2002 | 12665894 |
| the next influenza pandemic: lessons from hong kong. | pandemic influenza is a zoonosis. studies on influenza ecology conducted in hong kong since the 1970s in which hong kong essentially functioned as an influenza sentinel post indicated that it might be possible, for the first time, to have influenza preparedness at the baseline avian level. this appreciation of influenza ecology facilitated recognition of the h5n1 'bird flu' incident in hong kong in 1997 in what was considered to be an incipient pandemic situation, the chicken being the source of ... | 2003 | 12675938 |
| generation and evaluation of a high-growth reassortant h9n2 influenza a virus as a pandemic vaccine candidate. | h9n2 subtype avian influenza viruses (aivs) are widely distributed in avian species and were isolated from humans in hong kong and guangdong province, china in 1999 raising concern of their potential for pandemic spread. we generated a high-growth reassortant virus (g9/pr8) that contains the hemagglutinin (ha) and neuraminidase (na) genes from the h9n2 avian influenza virus a/chicken/hong kong/g9/97 (g9) and six internal genes from a/puerto rico/8/34 (pr8) by genetic reassortment, for evaluation ... | 2003 | 12706686 |
| phylogenetic analysis of the hemagglutinin genes of twenty-six avian influenza viruses of subtype h9n2 isolated from chickens in china during 1996-2001. | the complete coding region of hemagglutinin genes from 26 influenza a viruses of h9n2 subtype isolated from chicken flocks in china during 1996-2001 was amplified and sequenced. sequence analysis and phylogenetic studies of h9n2 subtype viruses on the basis of data of 26 viruses in this study and 71 selected strains available in the genbank were conducted. the results revealed that all the mainland china isolates showed high homology (94.19%-100%) and were assigned to a special sublineage in the ... | 2003 | 12713166 |
| 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 |
| seroprevalence of avian influenza virus and its relationship with increased mortality and decreased egg production. | to evaluate the occurrence of avian influenza viruses (aiv) infections in southern pakistan, an enzyme-linked immunosorbent assay was initially used to screen sera from broiler, layer and broiler breeder flocks for the presence of antibodies to type a influenza viruses. data from this survey showed high levels of aiv antibodies, indicating unrecognized aiv infection occurring in these flocks. based on this information a second investigation was undertaken in selected broiler-breeder, broiler and ... | 2003 | 12850918 |
| phylogenetic analysis of neuraminidase gene of h9n2 influenza viruses prevalent in chickens in china during 1995-2002. | the neuraminidase (na) genes of 12 h9n2 influenza virus strains isolated from diseased chickens in different farms in mainland china during 1995-2002 were amplified and sequenced. amino acids at hemadsorbing (hb) site of these isolates are different from those of a/quail/hong kong/g1/97-like viruses and a/chicken/korea/96-like viruses. neuraminidases of the 12 strains had a deletion of 3 amino acid residues at positions 63-65 as compared to that of a/turkey/wisconsin/189/66, while those of korea ... | 2003 | 14501198 |
| generation and characterization of a cold-adapted influenza a h9n2 reassortant as a live pandemic influenza virus vaccine candidate. | h9n2 subtype influenza a viruses have been identified in avian species worldwide and were isolated from humans in 1999, raising concerns about their pandemic potential and prompting the development of candidate vaccines to protect humans against this subtype of influenza a virus. reassortant h1n1 and h3n2 human influenza a viruses with the internal genes of the influenza a/ann arbor/6/60 (h2n2) (aa) cold-adapted (ca) virus have proven to be attenuated and safe as live virus vaccines in humans. u ... | 2003 | 14505926 |
| h9n2 influenza viruses prevalent in poultry in china are phylogenetically distinct from a/quail/hong kong/g1/97 presumed to be the donor of the internal protein genes of the h5n1 hong kong/97 virus. | ten h9n2 influenza virus strains isolated from diseased chickens in different farms in china during 1995 to 1999 were antigenically and genetically characterized. the haemagglutinins of the isolates were not related to those of a/quail/hong kong/g1/97 (h9n2) (qa/hk/g1/97), but were closely related to that of a/chicken/hong kong/g9/97 (h9n2) (ck/hk/g9/97). the neuraminidase of these isolates had a deletion of three amino acid residues at positions 63 to 65 as compared with those of ck/hk/g9/97, w ... | 2003 | 14522712 |
| report on avian influenza in the eastern hemisphere during 1997-2002. | since the fourth international symposium on avian influenza (ai) there has been considerable ai activity in the eastern hemisphere. the higher profile of ai resulting from the human infections with h5n1 and h9n2 viruses in hong kong, in 1997 and 1999, respectively, resulted in increased reporting and active surveillance. there have been three reported incidents of high-pathogenicity (hp) ai: h5n2 in northeastern italy in 1997 (eight outbreaks); h5n1 in hong kong in 1997 recurring in 2001 and 200 ... | 2003 | 14575066 |
| evaluation of pathogenic potential of avian influenza virus serotype h9n2 in chickens. | recently seven isolates of avian influenza virus (aiv) serotype h9n2 recovered from an outbreak of ai were analyzed on the basis of their biological and molecular characteristics. all the isolates belonged to the low-pathogenicity group of aiv. to further evaluate their pathogenic potential in association with other organisms, an isolate was inoculated experimentally in chickens using different routes and subsequently challenged with infectious bronchitis virus, ornithobacterium rhinotracheale o ... | 2003 | 14575070 |
| avian influenza (h9n2) outbreak in iran. | an epidemic of avian influenza (ai) (h9n2) occurred in broiler chicken farms in iran during 1998-01. mortality between 20% and 60% was commonly observed on the affected farms. mixed infections of the influenza virus with other respiratory pathogens, particularly infectious bronchitis virus and mycoplasma gallisepticum, were thought to be responsible for such high mortality, which resulted in great economic losses. clinical signs included swelling of the periorbital tissues and sinuses, typical r ... | 2003 | 14575072 |
| the quest of influenza a viruses for new hosts. | there is increasing evidence that stable lineages of influenza viruses are being established in chickens. h9n2 viruses are established in chickens in eurasia, and there are increasing reports of h3n2, h6n1, and h6n2 influenza viruses in chickens both in asia and north america. surveillance in a live poultry market in nanchang, south central china, reveals that influenza viruses were isolated form 1% of fecal samples taken from healthy poultry over the course of 16 months. the highest isolation r ... | 2003 | 14575076 |
| the impact of avian influenza viruses on public health. | in the late 1990s, h5n1 and h9n2 avian influenza viruses caused respiratory infections in humans in hong kong. exposure to domestic poultry in live-bird markets was significantly associated with human h5n1 disease. seroepidemiologic studies conducted among contacts of h5n1-infected persons determined that human-to-human transmission of the avian h5n1 viruses occurred but was rare. the relatively high rates of h5 and h9 antibody seroprevalence among hong kong poultry workers in 1997 highlight the ... | 2003 | 14575086 |
| safety evaluation in chickens of candidate human vaccines against potential pandemic strains of influenza. | two candidate formalin-inactivated vaccines, made from high-growth reassortant viruses with the ha and na genes from avian viruses in a background of genes derived from a/puerto rico/8/34 (pr8), were prepared against h5n1 and h9n2 subtypes (designated as h5n1/pr8 and h9n2/pr8, respectively). these viruses bear the genotypes, antigenicity, and attenuation in mouse models that are desirable in candidate vaccines. the pathogenicity of the newly generated avian-human reassortant vaccine viruses was ... | 2003 | 14575088 |
| the impact of a monthly rest day on avian influenza virus isolation rates in retail live poultry markets in hong kong. | retail live poultry markets (lpms) may act as a reservoir of avian influenza viruses (aiv). in this study we test the hypothesis that a rest day in the lpms where the stalls are completely emptied of poultry, cleansed, and restocked will reduce the isolation rates of avian influenza viruses. the isolation rate of h9n2 subtype viruses from chicken was significantly lower after the rest day than prior to it, indicating its impact in reducing transmission. in contrast, newcastle disease virus (ndv) ... | 2003 | 14575106 |
| sequence of ha gene of avian influenza a/chicken/guangdong/ss/1994 (h9n2) virus. | the rna of the hemagglutinin (ha) gene of a/chicken/guangdong/ss/1994 (h9n2) was reverse transcription-polymerase chain reaction amplified, and the cdna was cloned into a plasmid vector. the complete coding sequence of the ha gene was sequenced and included 1683 nucleotides, which encoded for a protein of 560 amino acids. the potential glycosylation sites related to ha protein function were highly conserved. the amino acid sequence of the ha proteolytic cleavage was g-s-s-r/g. this cleavage site ... | 2003 | 14575125 |
| 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 |
| differences between influenza virus receptors on target cells of duck and chicken and receptor specificity of the 1997 h5n1 chicken and human influenza viruses from hong kong. | to study whether influenza virus receptors in chickens differ from those in other species, we compared the binding of lectins and influenza viruses with known receptor specificity to cell membranes and gangliosides from epithelial tissues of ducks, chickens, and african green monkeys. we found that chicken cells contained neu5ac alpha(2-6)gal-terminated receptors recognized by sambucus nigra lectin and by human viruses. this finding explains how some recent h9n2 viruses replicate in chickens des ... | 2003 | 14575133 |
| phylogenetic analysis of hemagglutinin and neuraminidase genes of h9n2 viruses isolated from migratory ducks. | genetic analysis indicated that the pandemic influenza strains derived from wild aquatic birds harbor viruses of 15 hemagglutinin (ha) and 9 neuraminidase (na) antigenic subtypes. surveillance studies have shown that h9n2 subtype viruses are worldwide in domestic poultry and could infect mammalian species, including humans. here, we genetically analyzed the ha and na genes of five h9n2 viruses isolated from the migratory ducks in hokkaido, japan, the flyway of migration from siberia during 1997- ... | 2003 | 14618090 |
| influenza. | although most influenza infections are self-limited, few other diseases exert such a huge toll of suffering and economic loss. despite the importance of influenza, there had been, until recently, little advance in its control since amantadine was licensed almost 40 years ago. during the past decade, evidence has accrued on the protection afforded by inactivated vaccines and the safety and efficacy in children of live influenza-virus vaccines. there have been many new developments in vaccine tech ... | 2003 | 14643124 |
| structural differences among hemagglutinins of influenza a virus subtypes are reflected in their antigenic architecture: analysis of h9 escape mutants. | we used a panel of monoclonal antibodies to h9 hemagglutinin to select 18 escape mutants of mouse-adapted influenza a/swine/hong kong/9/98 (h9n2) virus. cross-reactions of the mutants with the antibodies and the sequencing of hemagglutinin genes revealed two minimally overlapping epitopes. we mapped the amino acid changes to two areas of the recently reported three-dimensional structure of a/swine/hong kong/9/98 hemagglutinin. the grouping of the antigenically relevant amino acid positions in h9 ... | 2004 | 14671105 |
| safety and antigenicity of whole virus and subunit influenza a/hong kong/1073/99 (h9n2) vaccine in healthy adults: phase i randomised trial. | in 1999, avian influenza a/hong kong/1073/99 (h9n2) virus emerged as a pandemic threat to human beings. we aimed to assess safety, tolerability, and antigenicity of whole virus and subunit h9n2 vaccines in healthy volunteers. | 2003 | 14683655 |
| generation of high-yielding influenza a viruses in african green monkey kidney (vero) cells by reverse genetics. | influenza a viruses are the cause of annual epidemics of human disease with occasional outbreaks of pandemic proportions. the zoonotic nature of the disease and the vast viral reservoirs in the aquatic birds of the world mean that influenza will not easily be eradicated and that vaccines will continue to be needed. recent technological advances in reverse genetics methods and limitations of the conventional production of vaccines by using eggs have led to a push to develop cell-based strategies ... | 2004 | 14747549 |
| human and avian influenza viruses target different cell types in cultures of human airway epithelium. | the recent human infections caused by h5n1, h9n2, and h7n7 avian influenza viruses highlighted the continuous threat of new pathogenic influenza viruses emerging from a natural reservoir in birds. it is generally believed that replication of avian influenza viruses in humans is restricted by a poor fit of these viruses to cellular receptors and extracellular inhibitors in the human respiratory tract. however, detailed mechanisms of this restriction remain obscure. here, using cultures of differe ... | 2004 | 15070767 |
| attenuation of a human h9n2 influenza virus in mammalian host by reassortment with an avian influenza virus. | in order to develop a surrogate virus strain for production of an inactivated influenza vaccine against a human h9n2 virus, a/hong kong/1073/99 (hk1073: h9n2) was co-infected in embryonated chicken eggs with an apathogenic avian influenza virus, a/duck/czechoslovakia/56 (dk/cz: h4n6), for gene segment reassortment. multiple-gene reassortants obtained were examined for replication in mammalian hosts in vitro and in vivo by infecting mdck cells and by intranasal administration to hamsters, respect ... | 2004 | 15221539 |
| the interferon-alpha genes from three chicken lines and its effects on h9n2 influenza viruses. | the interferon-alpha genes from three chicken lines were cloned by a direct pcr technique, and the effects of recombinant protein expressed in a prokaryotic system on highly pathogenic h9n2 influenza viruses were investigated. the cloned chifn-alpha gene encoded a protein of 193 amino acids with a signal sequence of 31 amino acids and mature peptides of 162 amino acids. comparison of chifn-alpha sequences, detected six amino acids substitutions at positions 50, 58, 65, 81, 181, and 183. homology ... | 2004 | 15248602 |
| continuing evolution of h9n2 influenza viruses in southeastern china. | h9n2 influenza viruses are panzootic in domestic poultry in eurasia and since 1999 have caused transient infections in humans and pigs. to investigate the zoonotic potential of h9n2 viruses, we studied the evolution of the viruses in live-poultry markets in hong kong in 2003. h9n2 was the most prevalent influenza virus subtype in the live-poultry markets between 2001 and 2003. antigenic and phylogenetic analysis of hemagglutinin (ha) showed that all of the 19 isolates found except one belonged t ... | 2004 | 15280470 |
| isolation and identification of swine influenza recombinant a/swine/shandong/1/2003(h9n2) virus. | ten influenza virus isolates were obtained from infected pigs from different places in shandong province showing clinical symptoms from october 2002 to january 2003. all 10 isolates were identified in china's national influenza research center as influenza a virus of h9n2 subtype. the complete genome of one isolate, designated a/swine/shandong/1/2003(h9n2), was sequenced and compared with sequences available in genbank. the results of analyses indicated that the sequence of a/swine/shandong/1/20 ... | 2004 | 15310468 |
| [characterization of ha and na genes of swine influenza a (h9n2) viruses]. | to understand the origin of ha and na genes of swine influenza a (h9n2) viruses isolated from pigs in the mainland of china and on basis of these to reveal the pathogenicity of them in pigs. | 2004 | 15340516 |
| [characterization of internal genes of two strains of influenza a (h9n2) virus isolated from men]. | to understand the characteristics of internal genes of two strains of influenza a(h9n2) virus isolated from men and on the basis of these to reveal the origin of these two strains of influenza a(h9n2)virus. | 2003 | 15340563 |
| co-infection of staphylococcus aureus or haemophilus paragallinarum exacerbates h9n2 influenza a virus infection in chickens. | h9n2 influenza viruses are frequently isolated from chicken meat and bone marrow imported from china to japan since 2001. these isolates were experimentally inoculated into specific pathogen-free chickens intranasally. viruses were recovered from the meat and bone marrow of birds showing no overt signs. on the other hand, chickens co-infected with h9n2 virus and either staphylococcus aureus or haemophilus paragallinarum showed clinical signs severer than those shown by birds infected only with t ... | 2004 | 15503199 |
| genetic conservation of hemagglutinin gene of h9 influenza virus in chicken population in mainland china. | the hemagglutinin (ha) genes of 12 h9n2 influenza virus strains isolated from chickens in mainland china during the period 1995-2002 were genetically analyzed. all the isolates possessed the same amino acid motif -r-s-s-r/g-l- at the cleavage site of ha. except for the conserved amino acids, as is the case in the other avian influenza viruses, located in the receptor binding site, all of the 12 isolates possessed n at amino acid position 183; a, t, or v at position 190; k at position 137, wherea ... | 2004 | 15550773 |
| [discoveries of avian influenza a(h9n2) virus in chickens and men infected by h9n2 virus in guangzhou area]. | to understand the epidemic status of avian influenza a virus in chickens and men in guangzhou area and to prevent men suffering from avian influenza a (h5n1) virus. | 2004 | 15640850 |
| development of enzyme-linked immunosorbent assay with nucleoprotein as antigen for detection of antibodies to avian influenza virus. | during the avian influenza outbreak of 2003-04 in southeast asia, two avian influenza viruses (aiv), one of h5n1 subtype and the other h9n2 subtype, were isolated and identified from local farms. the nudeoprotein (np) gene of the h5n1 ai isolate was cloned, and the segment encoding amino acid 47-384, which covers its major antigenic domains, was subcloned and expressed in e. coli. subsequently, the np (47-384) expression product was purified and used as the diagnostic antigen to develop a np-bas ... | 2004 | 15666868 |
| avian influenza viruses in korean live poultry markets and their pathogenic potential. | we surveyed live-poultry markets in korea in 2003 and isolated 9 h9n2, 6 h3n2, and 1 h6n1 influenza viruses. antigenic and phylogenetic analyses showed that all 9 h9n2 isolates were of a/chicken/korea/25232-96006/96-like lineage (which caused disease in chickens in korea in 1996) but were different from h9n2 viruses of southeastern china. they had at least 4 genotypes and replicated in chickens but not in mice. the h3n2 and h6n1 viruses were new to korea and were probably reassortants of avian i ... | 2005 | 15680418 |
| microbial adaptation and change: avian influenza. | the evolution of influenza is a continuing process involving viral and host factors. the increasing frequency of emergence of the highly pathogenic h5n1, h7n3 and h7n7 influenza viruses and the panzootic spread of h9n2 influenza virus, all of which can be potentially transmitted to humans, are of great concern to both veterinary and human public health officials. the question is how soon the next pandemic will emerge. a convergence of factors, including the population densities of poultry, pigs ... | 2004 | 15702713 |
| sialobiology of influenza: molecular mechanism of host range variation of influenza viruses. | the gene pool of influenza a viruses in aquatic birds provides all of the genetic diversity required for human and lower animals. host range selection of the receptor binding specificity of the influenza virus hemagglutinin occurs during maintenance of the virus in different host cells that express different receptor sialo-sugar chains. in this paper, functional roles of the hemagglutinin and neuraminidase spikes of influenza viruses are described in the relation to 1) host range of influenza vi ... | 2005 | 15744059 |
| isolation and characterization of avian influenza viruses, including highly pathogenic h5n1, from poultry in live bird markets in hanoi, vietnam, in 2001. | since 1997, outbreaks of highly pathogenic (hp) h5n1 and circulation of h9n2 viruses among domestic poultry in asia have posed a threat to public health. to better understand the extent of transmission of avian influenza viruses (aiv) to humans in asia, we conducted a cross-sectional virologic study in live bird markets (lbm) in hanoi, vietnam, in october 2001. specimens from 189 birds and 18 environmental samples were collected at 10 lbm. four influenza a viruses of the h4n6 (n = 1), h5n2 (n = ... | 2005 | 15767421 |
| [is avian influenza a risk for humans?]. | avian influenza is an infectious disease of birds, caused by type a strains of the influenza virus. the disease, which was first identified in italy more than 100 years ago, occurs worldwide. avian influenza viruses are mainly distributed by migratory birds. different mammals like swine, horse and finally humans are susceptible for avian influenza viruses. the high possibility of genomic changes like gene shift and drift is caused by the segmented rna genome. during the avian flu outbreak in eas ... | 2005 | 15812719 |
| [generation of attenuated h5n1 and h5n2 subtypes of influenza virus recombinants by reverse genetics system]. | the ha connecting peptide at cleavage site, pqrerrkkr / gl, of an h5n1 subtype avian influenza virus (aiv) was replaced with pqresr / gl, and then the modified ha gene was cloned into the transcription/expression vector, phw2000, constructing a plasmid named phw524-ha. the na (n1) gene from the h5n1 virus and the na (n2) gene from an h9n2 aiv were also cloned into phw2000 separately, resulting in plasmids phw506-na and phw206-na. with the organization of phw524-ha, phw506-na or phw206-na, and si ... | 2005 | 15847163 |
| [generation of a/chicken/shanghai/f/98 (h9n2) avian influenza virus from eight plasmids]. | eight-plasmid system was used for the generation of avian influenza virus (aiv) strain a/chicken/shanghai/f/98 (h9n2) which was isolated in china in 1998. in this plasmid-based expression system, viral cdna was inserted beteen the rna polymerase i (pol i) promoter and terminator sequences. the entire pol i transcription unit was flanked by an rna polymerase ii (pol ii) promoter and a poly (a) site. twenty-four hours after the transfection of eight expression plasmid into cos1 cells, the supernat ... | 2005 | 15989229 |
| [expression of hemagglutinin of avian influenza virus (aiv) and its application in diagnosis of aiv h9 subtype]. | in order to differently diagnose avian influenza virus (aiv) subtypes, the ha gene of aiv h9 subtype was cloned, expressed and utilized in an enzyme-linked immunoad sorbent assay (elisa). ha gene (1683bp) of h9n2 aiv was amplified by rt-pcr from a strain of field isolated h9n2 aiv, and its identity was confirmed by sequencing. the ha gene was subcloned into prokaryotic expression vector pgex-kg with its secretion signal sequence removed. the expressed ha-gst fusion protein in e. coli bl21 was ch ... | 2005 | 16013497 |
| phylogenetic analysis of eight genes of h9n2 subtype influenza virus: a mainland china strain possessing early isolates' genes that have been circulating. | h9n2 subtype influenza virus has become worldwide and prevalent in china. previous studies illustrated that at least three sublineages had been established in terrestrial poultry of eurasian avian. in this presentation, eight full-length genes of an h9n2 strain, a/chicken/shanghai/f/98 (ck/sh/f/98) were obtained. sequence analysis and phylogenetic studies were conducted by comparing eight genes with those of all the available h9n2 strains from the genbank. the results showed that four genes (ha, ... | 2005 | 16025241 |