| perpetuation of influenza a viruses in alaskan waterfowl reservoirs. | to provide information on the mechanism of perpetuation of influenza viruses among waterfowl reservoirs in nature, virological surveillance was carried out in alaska during their breeding season in summer from 1991 to 1994. influenza viruses were isolated mainly from fecal samples of dabbling ducks in their nesting places in central alaska. the numbers of subtypes of 108 influenza virus isolates were 1 h2n3, 37 h3n8, 55 h4n6, 1 h7n3, 1 h8n2, 1 h10n2, 11 h10n7, and h10n9. influenza viruses were a ... | 1995 | 7646350 |
| influenza virus subtypes in aquatic birds of eastern germany. | we report the findings of a 12-year surveillance study (1977-89) of avian influenza a viruses in eastern germany. viruses were isolated directly from feral ducks (n = 236) and other wild birds (n = 89); from domestic ducks (n = 735) living on a single farm; and from white pekin ducks (n = 193) used as sentinels for populations of wild aquatic birds; mainly sea birds. the efficiency of virus isolation was 9.9% overall, with considerable variability noted among species: 8.7% in wild ducks, 0.9% in ... | 1994 | 8198436 |
| cross-protection of mice immunized with different influenza a (h2) strains and challenged with viruses of the same ha subtype. | cross-protection of mice immunized with inactivated preparations of human and avian influenza a (h2) viruses was determined after lethal infection with mouse-adapted (ma) variants of human a/jap x bell/57 (h2n1) and avian a/njers/78 (h2n3) viruses. the ma variants differed from the original strains by acquired virulence for mice and changes in the ha antigenicity. these studies indicated that mice vaccinated with human influenza a (h2) viruses were satisfactorily protected against challenge with ... | 1997 | 9607078 |
| [gene analysis and phenotypic characteristic of highly-reproductive reassortants, containing the gene for bird influenza virus subtype h2 hemagglutinin]. | a series of reassortant clones with antigenic formulae h2n1 and h2n3 were produced by genetic reassortment performed with the use of an avian influenza virus, a/pintail duck/primorie/695/76 (h2n3) and a high-yield reassortant strain x-67. preliminary identification of the parent origin of np and ns genes for 5 reassortants was performed by comparison of the mobilities of virus-specific proteins in polyacrylamide gel electrophoresis. the parent origin of genes of internal and nonstructural protei ... | 2000 | 10695039 |
| intergenic ha-na interactions in influenza a virus: postreassortment substitutions of charged amino acid in the hemagglutinin of different subtypes. | in our previous studies influenza a virus reassortants having neuraminidase (na) gene of a/ussr/90/77 (h1n1) strain and hemagglutinin (ha) genes of h3, h4 and h13 subtypes were shown to produce a low virus yield and to exhibit a strong tendency to virion aggregation. more detailed studies with the use of a h3n1 reassortant and its high-yield non-aggregating variants revealed that na of a/ussr/90/77 strain is inefficient in the removal of the terminal sialic acid residues from the virion componen ... | 2000 | 10725545 |
| cross-protection and reassortment studies with avian h2 influenza viruses. | in order to assess the degree of immune cross-protection among avian h2 influenza virus strains, mice were immunised with beta-propiolactone-inactivated virus preparations and infected intranasally with mouse-adapted variant of a/black duck/new jersey/1580/78 (h2n3) strain. the experiments with 11 avian h2 strains revealed that both eurasian and american h2 avian influenza viruses exhibit either high or moderate degree of cross-protection. the grouping of the strains in accordance with their cro ... | 2000 | 10948982 |
| preparation of a standardized, efficacious agricultural h5n3 vaccine by reverse genetics. | options for the control of emerging and reemerging h5n1 influenza viruses include improvements in biosecurity and the use of inactivated vaccines. commercially available h5n2 influenza vaccine prevents disease signs and reduces virus load but does not completely prevent virus shedding after challenge with h5n1 virus. by using reverse genetics, we prepared an h5n3 vaccine whose hemagglutinin is 99.6% homologous to that of a/ck/hk/86.3/02 (h5n1). we used the internal genes of a/pr/8/34 and the h5 ... | 2003 | 14554086 |
| interregional transmission of the internal protein genes of h2 influenza virus in migratory ducks from north america to eurasia. | h2 influenza virus caused a pandemic in 1957 and has the possibility to cause outbreaks in the future. to assess the evolutionary characteristics of h2 influenza viruses isolated from migratory ducks that congregate in hokkaido, japan, on their flyway of migration from siberia in 2001, we investigated the phylogenetic relationships among these viruses and avian and human viruses described previously. phylogenetic analysis showed that the pb2 gene of dk/hokkaido/107/01 (h2n3) and the pa gene of d ... | 2004 | 15215686 |
| influenza virus circulation in wild aquatic birds in italy during h5n2 and h7n1 poultry epidemic periods (1998 to 2000). | two epidemics of avian influenza due to h5 and h7 highly pathogenic viruses occurred in poultry in italy in 1997/98 and 1999/2000, respectively. the circulation of these serotypes in wild aquatic birds was investigated examining 638 cloacal swabs and 621 sera collected from 150 gulls, 162 coots, and 326 ducks trapped in italian wetlands from 1998 to 2000. seroprevalences against influenza a viruses, detected by a double-antibody sandwich-blocking enzyme-linked immunosorbent assay (elisa), were 1 ... | 2005 | 16537162 |
| [generation high yield vaccine strain wholly derived from avian influenza viruses by reverse genetics]. | highly pathogenic avian influenza a (hpai) viruses of the h5n1 subtypes caused enormous economical loss to poultry farms in china and southeastern asian countries. the vaccination program is a reliable strategy in controlling the prevalence of these disastrous diseases. the six internal genes of the high-yield influenza virus a/goose/dalian/3/01 (h9n2), the hemagglutinin (ha) gene of a/goose/hlj/qfy/04 (h5n1) strain, and the neuraminidase gene from a/duck/germany/1215/73 (h2n3) reference strain ... | 2006 | 17037192 |
| identification of h2n3 influenza a viruses from swine in the united states. | although viruses of each of the 16 influenza a ha subtypes are potential human pathogens, only viruses of the h1, h2, and h3 subtype are known to have been successfully established in humans. h2 influenza viruses have been absent from human circulation since 1968, and as such they pose a substantial human pandemic risk. in this report, we isolate and characterize genetically similar avian/swine virus reassortant h2n3 influenza a viruses isolated from diseased swine from two farms in the united s ... | 2007 | 18093945 |
| amplification of four genes of influenza a viruses using a degenerate primer set in a one step rt-pcr method. | we designed a degenerate primer set that yielded full-length amplification of hemagglutinin (ha), neuraminidase (na), matrix (m), and non-structural protein (nsp) genes of influenza a viruses in a single reaction mixture. these four genes were amplified from 15 ha (1-15) and 9 na (1-9) subtypes of influenza a viruses of avian (n=16) origin. in addition, 272 field isolates of avian origin were tested by this method. full-length amplification of ha, na, m, and nsp genes was obtained in 242 (88.9%) ... | 2009 | 19447141 |
| the pig as a mixing vessel for influenza viruses: human and veterinary implications. | influenza a viruses are highly infectious respiratory pathogens that can infect many species. birds are the reservoir for all known influenza a subtypes; and novel influenza viruses can emerge from birds and infect mammalian species including humans. because swine are susceptible to infection with both avian and human influenza viruses, novel reassortant influenza viruses can be generated in this mammalian species by reassortment of influenza viral segments leading to the "mixing vessel" theory. ... | 2008 | 19565018 |
| detection of anti-influenza a nucleoprotein antibodies in pigs using a commercial influenza epitope-blocking enzyme-linked immunosorbent assay developed for avian species. | influenza virus causes acute respiratory disease in pigs and is of concern for its potential public health significance. many subtypes of influenza virus have been isolated from pigs, and the virus continues to evolve in swine populations. current antibody assays have limited antigenic recognition, and accurate, broad-spectrum, high through-put screening tests are needed to detect infections in swine herds and to aid in the implementation of control measures. in the current study, a commercial b ... | 2010 | 20093676 |
| serologic survey of swine workers for exposure to h2n3 swine influenza a. | of the 16 influenza a hemagglutinin (h) subtypes, only h1, h2 and h3 viruses have been shown to cause sustained human infection. whereas h1 and h3 viruses currently circulate seasonally in humans, h2 viruses have not been identified in humans since 1968. in 2006, an h2n3 influenza virus was isolated from ill swine in the united states. | 2010 | 20409213 |
| evaluation of replication and cross-reactive antibody responses of h2 subtype influenza viruses in mice and ferrets. | h2 influenza viruses have not circulated in humans since 1968, and therefore a large segment of the population would likely be susceptible to infection should h2 influenza viruses reemerge. the development of an h2 pandemic influenza virus vaccine candidate should therefore be considered a priority in pandemic influenza preparedness planning. we selected a group of geographically and temporally diverse wild-type h2 influenza viruses and evaluated the kinetics of replication and compared the abil ... | 2010 | 20504935 |
| thermostability of subpopulations of h2n3 influenza virus isolates from mallard ducks. | maintenance of avian influenza virus in waterfowl populations requires that virions remain infectious while in the environment. temperature has been shown to negatively correlate with persistence time, which is the duration for which virions are infectious. however, thermostability can vary between isolates regardless of subtype, and it is not known whether this variation occurs when host and geographic location of isolation are controlled. in this study, we analyzed the thermostabilities of 7 h ... | 2010 | 20610728 |
| rapid death of duck cells infected with influenza: a potential mechanism for host resistance to h5n1. | aquatic birds are the natural reservoir for most subtypes of influenza a, and a source of novel viruses with the potential to cause human pandemics, fatal zoonotic disease or devastating epizootics in poultry. it is well recognised that waterfowl typically show few clinical signs following influenza a infection, in contrast, terrestrial poultry such as chickens may develop severe disease with rapid death following infection with highly pathogenic avian influenza. this study examined the cellular ... | 2011 | 21423263 |
| replication of low pathogenic avian influenza virus in naturally infected mallard ducks (anas platyrhynchos) causes no morphologic lesions. | although the mallard (anas platyrhynchos) is considered an important maintenance host for low pathogenic avian influenza (lpai) viruses, viral cell tropism and pathology in naturally infected birds are largely unknown. in august 2006, we collected 19 free-living hatch-year mallards that were positive for lpai virus by real-time reverse-transcriptase polymerase chain reaction (rrt-pcr) in combined oropharyngeal and cloacal swabs. we investigated virus infection and associated lesions in the diges ... | 2011 | 21441193 |
| influenza virus-like particle can accommodate multiple subtypes of hemagglutinin and protect from multiple influenza types and subtypes. | despite existing vaccines and specific therapies, epidemics of seasonal influenza annually claim 200,000-500,000 lives worldwide. pandemic influenza represents an even greater threat, with numerous potentially pandemic viruses circulating in nature. development of multi-specific vaccines against multiple pandemic or seasonal strains is important for human health and the global economy. here we report a novel virus-like particle (vlp) platform that contains three hemagglutinin (ha) subtypes. this ... | 2011 | 21723354 |
| influenza-a viruses in ducks in northwestern minnesota: fine scale spatial and temporal variation in prevalence and subtype diversity. | waterfowl from northwestern minnesota were sampled by cloacal swabbing for avian influenza virus (aiv) from july-october in 2007 and 2008. aiv was detected in 222 (9.1%) of 2,441 ducks in 2007 and in 438 (17.9%) of 2,452 ducks in 2008. prevalence of aiv peaked in late summer. we detected 27 aiv subtypes during 2007 and 31 during 2008. ten hemagglutinin (ha) subtypes were detected each year (i.e., h1, 3-8, and 10-12 during 2007; h1-8, 10 and 11 during 2008). all neuraminidase (na) subtypes were d ... | 2011 | 21931636 |
| identification and characterization of h2n3 avian influenza virus from backyard poultry and comparison with novel h2n3 swine influenza virus. | in early 2007, h2n3 influenza virus was isolated from a duck and a chicken in two separate poultry flocks in ohio. since the same subtype influenza virus with hemagglutinin (h) and neuraminidase (n) genes of avian lineage was also identified in a swine herd in missouri in 2006, the objective of this study was to characterize and compare the genetic, antigenic, and biologic properties of the avian and swine isolates. avian isolates were low pathogenic by in vivo chicken pathogenicity testing. seq ... | 2011 | 22312981 |
| a novel reassortant h2n3 influenza virus isolated from china. | to analyze the genetic composition of a novel h2n3 virus isolate identified from a duck cage swab in a live poultry market (lpm) in 2009 in guangdong province of china. | 2014 | 24758752 |
| is there a relation between genetic or social groups of mallard ducks and the circulation of low pathogenic avian influenza viruses? | we investigated the circulation dynamics of low pathogenic avian influenza viruses (lpaivs) in the mallard (anas platyrhynchos) reservoir in italy. in particular, we evaluated the temporal distribution of virologic findings by combining virus isolation data with a new population genetic-based study approach. thus, during 11 consecutive sampling periods (wintering periods between 1993/94 and 2003/04), categorised into 40 sampling sub-periods, cloacal swab samples were collected from 996 wild and ... | 2014 | 24690373 |
| long-term variation in influenza a virus prevalence and subtype diversity in migratory mallards in northern europe. | data on long-term circulation of pathogens in wildlife populations are seldom collected, and hence understanding of spatial-temporal variation in prevalence and genotypes is limited. here, we analysed a long-term surveillance series on influenza a virus (iav) in mallards collected at an important migratory stopover site from 2002 to 2010, and characterized seasonal dynamics in virus prevalence and subtype diversity. prevalence dynamics were influenced by year, but retained a common pattern for a ... | 2014 | 24573857 |
| replication of 2 subtypes of low-pathogenicity avian influenza virus of duck and gull origins in experimentally infected mallard ducks. | many subtypes of low-pathogenicity avian influenza (lpai) virus circulate in wild bird reservoirs, but their prevalence may vary among species. we aimed to compare by real-time reverse-transcriptase polymerase chain reaction, virus isolation, histology, and immunohistochemistry the distribution and pathogenicity of 2 such subtypes of markedly different origins in mallard ducks (anas platyrhynchos): h2n3 isolated from a mallard duck and h13n6 isolated from a ring-billed gull (larus delawarensis). ... | 2013 | 23242805 |
| early apoptosis of porcine alveolar macrophages limits avian influenza virus replication and pro-inflammatory dysregulation. | pigs are evidently more resistant to avian than swine influenza a viruses, mediated in part through frontline epithelial cells and alveolar macrophages (am). although porcine am (pam) are crucial in influenza virus control, their mode of control is unclear. to gain insight into the possible role of pam in the mediation of avian influenza virus resistance, we compared the host effects and replication of two avian (h2n3 and h6n1) and three mammalian (swine h1n1, human h1n1 and pandemic h1n1) influ ... | 2015 | 26642934 |
| chicken and duck myotubes are highly susceptible and permissive to influenza virus infection. | skeletal muscle, at 30 to 40% of body mass, is the most abundant soft tissue in the body. besides its primary function in movement and posture, skeletal muscle is a significant innate immune organ with the capacity to produce cytokines and chemokines and respond to proinflammatory cytokines. little is known about the role of skeletal muscle during systemic influenza a virus infection in any host and particularly avian species. here we used primary chicken and duck multinucleated myotubes to exam ... | 2015 | 25540384 |
| pre-exposing canada geese (branta canadensis) to a low-pathogenic h1n1 avian influenza virus protects them against h5n1 hpai virus challenge. | in previous studies we examined the role of canada geese (branta canadensis) in the epidemiology of eurasian highly pathogenic avian influenza (hpai) h5n1. to expand on this and better understand how pre-exposure to heterosubtypic low-pathogenic avian influenza (lpai) viruses might influence the outcome of h5n1 hpai infection, we pre-exposed naïve juvenile canada geese to different north american wild-bird-origin lpai viruses. we selected h1, h2, and h6 hemagglutinin subtype viruses based on the ... | 2014 | 24171557 |
| evaluation of multivalent h2 influenza pandemic vaccines in mice. | subtype h2 influenza a viruses were the cause of a severe pandemic in the winter of 1957. however, this subtype no longer circulates in humans and is no longer included in seasonal vaccines. as a result, individuals under 50years of age are immunologically naïve. h2 viruses persist in aquatic birds, which were a contributing source for the 1957 pandemic, and have also been isolated from swine. reintroduction of the h2 via zoonotic transmission has been identified as a pandemic risk, so pre-pande ... | 2017 | 28189402 |
| assessment of transmission, pathogenesis and adaptation of h2 subtype influenza viruses in ferrets. | after their disappearance from the human population in 1968, influenza h2 viruses have continued to circulate in the natural avian reservoir. the isolation of this virus subtype from multiple bird species as well as swine highlights the need to better understand the potential of these viruses to spread and cause disease in humans. here we analyzed the virulence, transmissibility and receptor-binding preference of two avian influenza h2 viruses (h2n2 and h2n3) and compared them to a swine h2n3 (a ... | 2015 | 25659818 |
| evaluation of three live attenuated h2 pandemic influenza vaccine candidates in mice and ferrets. | h2 influenza viruses have not circulated in humans since 1968, and therefore a significant portion of the population would be susceptible to infection should h2 influenza viruses reemerge. h2 influenza viruses continue to circulate in avian reservoirs worldwide, and these reservoirs are a potential source from which these viruses could emerge. three reassortant cold-adapted (ca) h2 pandemic influenza vaccine candidates with hemagglutinin (ha) and neuraminidase (na) genes derived from the wild-ty ... | 2014 | 24371061 |
| recently emerged swine influenza a virus (h2n3) causes severe pneumonia in cynomolgus macaques. | the triple reassortant h2n3 virus isolated from diseased pigs in the united states in 2006 is pathogenic for certain mammals without prior adaptation and transmits among swine and ferrets. adaptation, in the h2 hemagglutinin derived from an avian virus, includes the ability to bind to the mammalian receptor, a significant prerequisite for infection of mammals, in particular humans, which poses a big concern for public health. here we investigated the pathogenic potential of swine h2n3 in cynomol ... | 2012 | 22808082 |
| human monoclonal antibodies to pandemic 1957 h2n2 and pandemic 1968 h3n2 influenza viruses. | investigation of the human antibody response to the 1957 pandemic h2n2 influenza a virus has been largely limited to serologic studies. we generated five influenza virus hemagglutinin (ha)-reactive human monoclonal antibodies (mabs) by hybridoma technology from the peripheral blood of healthy donors who were born between 1950 and 1968. two mabs reacted with the pandemic h2n2 virus, two recognized the pandemic h3n2 virus, and remarkably, one reacted with both the pandemic h2n2 and h3n2 viruses. e ... | 2012 | 22457520 |
| dna microarray global gene expression analysis of influenza virus-infected chicken and duck cells. | the data described in this article pertain to the article by kuchipudi et al. (2014) titled "highly pathogenic avian influenza virus infection in chickens but not ducks is associated with elevated host immune and pro-inflammatory responses" [1]. while infection of chickens with highly pathogenic avian influenza (hpai) h5n1 virus subtypes often leads to 100% mortality within 1 to 2 days, infection of ducks in contrast causes mild or no clinical signs. the rapid onset of fatal disease in chickens, ... | 2015 | 26484178 |
| identification of morphological differences between avian influenza a viruses grown in chicken and duck cells. | although wild ducks are considered to be the major reservoirs for most influenza a virus subtypes, they are typically resistant to the effects of the infection. in contrast, certain influenza viruses may be highly pathogenic in other avian hosts such as chickens and turkeys, causing severe illness and death. following in vitro infection of chicken and duck embryo fibroblasts (cef and def) with low pathogenic avian influenza (lpai) viruses, duck cells die more rapidly and produce fewer infectious ... | 2015 | 25613009 |
| highly pathogenic avian influenza virus infection in chickens but not ducks is associated with elevated host immune and pro-inflammatory responses. | highly pathogenic avian influenza (hpai) h5n1 viruses cause severe infection in chickens at near complete mortality, but corresponding infection in ducks is typically mild or asymptomatic. to understand the underlying molecular differences in host response, primary chicken and duck lung cells, infected with two hpai h5n1 viruses and a low pathogenicity avian influenza (lpai) h2n3 virus, were subjected to rna expression profiling. chicken cells but not duck cells showed highly elevated immune and ... | 2014 | 25431115 |
| efficacy of a high-yield attenuated vaccine strain wholly derived from avian influenza viruses by use of reverse genetics. | the preparation of high-yield influenza h5n1 vaccine strains is challenging for researchers and manufacturers. here, we used reverse genetics to generate a high-yield avian influenza vaccine strain based on a novel avian influenza virus. a high-yield attenuated recombinant h5n3 virus (rh5n3-dl) was prepared from the ha gene of a/goose/anhui/08 (h5n1), modified by deletion of the multiple basic amino acids at the cleavage site, the na gene from a/duck/germany/1215/73 (h2n3), and the six internal ... | 2012 | 22832374 |
| consecutive natural influenza a virus infections in sentinel mallards in the evident absence of subtype-specific hemagglutination inhibiting antibodies. | dabbling ducks, particularly mallards (anas platyrhynchos) have been frequently and consistently reported to play a pivotal role as a reservoir of low pathogenic avian influenza viruses (aiv). from october 2006 to november 2008, hand-raised mallard ducks kept at a pond in an avifaunistically rich area of southern germany served as sentinel birds in the aiv surveillance programme in germany. the pond was regularly visited by several species of dabbling ducks. a flock of sentinel birds, consisting ... | 2013 | 22816511 |
| presence of avian influenza viruses in waterfowl and wetlands during summer 2010 in california: are resident birds a potential reservoir? | although wild waterfowl are the main reservoir for low pathogenic avian influenza viruses (lpaiv), the environment plays a critical role for the circulation and persistence of aiv. lpaiv may persist for extended periods in cold environments, suggesting that waterfowl breeding areas in the northern hemisphere may be an important reservoir for aiv in contrast to the warmer southern wintering areas. we evaluated whether southern wetlands, with relatively small populations (thousands) of resident wa ... | 2012 | 22328934 |
| sequence of the nucleoprotein (np) gene of the influenza alanas acuta/primorje/695/76 (h2n3) virus. | | 1991 | 2062661 |