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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

C-type lectin immunoreceptor genes encoding DC inhibitory and activating receptors (DCIR and DCAR) were identified in a spleen EST library of duck (Anas platyrhynchos). These receptors are of interest for their potential as regulators of antigen presenting cells. A genomic clone was isolated and fully sequenced, containing one DCIR gene and two DCAR genes arranged in tandem order. Duck DCIR encodes an inhibitory receptor that features an immunoreceptor tyrosine-based inhibitory motif (ITIM) in the cytoplasmic domain. DCAR1 is a pseudogene. DCAR2 encodes an activating receptor with a positively charged residue in the transmembrane region. Full-length and alternatively spliced forms of both DCIR and DCAR2 are apparent. Duck DCIR and DCAR transcripts are preferentially expressed in immune and mucosal tissues including spleen, bursa of Fabricius, intestine and lung. Targeting these receptors on dendritic cells holds potential for breaking tolerance or for enhancing immune responses, relevant to the duck model for hepatitis B and vaccination against avian influenza.
Mol Immunol 2008 Sep
PMID:Dendritic cell inhibitory and activating immunoreceptors (DCIR and DCAR) in duck: Genomic organization and expression. 1865 64

Adaptation of avian influenza viruses for replication and transmission in the human host is believed to require mutations in the hemagglutinin glycoprotein (HA) which enable binding to human alpha2-6 sialosides and concomitant reduction in affinity for avian alpha2-3 linked sialosides. Here, we show by glycan microarray analyses that the two mutations responsible for such specificity changes in 1957 H2N2 and 1968 H3N2 pandemic viruses, when inserted into recombinant HAs or intact viruses of some recent avian H5N1 isolates (clade 2.2), impart such attributes. This propensity to adapt to human receptors is primarily dependent on arginine at position 193 within the receptor-binding site, as well as loss of a vicinal glycosylation site. Widespread occurrence of these susceptible H5N1 clade 2.2 influenza strains has already occurred in Europe, the Middle East, and Africa. Thus, these avian strains should be considered high-risk, because of their significantly lower threshold for acquiring human receptor specificity and, therefore, warrant increased surveillance and further study.
J Mol Biol 2008 Sep 19
PMID:Recent avian H5N1 viruses exhibit increased propensity for acquiring human receptor specificity. 1867 52

Avian influenza A viruses (AIVs), including the H5N1, H9N2, and H7N7 subtypes, have been directly transmitted to humans, raising concerns over the possibility of a new influenza pandemic. To prevent a future avian influenza pandemic, it is very important to fully understand the molecular basis driving the change in AIV virulence and host tropism. Although virulent variants of other viruses have been generated by homologous recombination, the occurrence of homologous recombination within AIV segments is controversial and far from proven. This study reports three circulating H9N2 AIVs with similar mosaic PA genes descended from H9N2 and H5N1. Additionally, many homologous recombinants are also found deposited in GenBank. Recombination events can occur in PB2, PB1, PA, HA, and NP segments and between lineages of the same/different serotype. These results collectively demonstrate that intragenic recombination plays a role in driving the evolution of AIVs, potentially resulting in effects on AIV virulence and host tropism changes.
Mol Biol Evol 2009 Jan
PMID:Homologous recombination as an evolutionary force in the avian influenza A virus. 1893 84

We have applied the temperature-dependent single-stranded conformational polymorphism (SSCP) analysis for characterization of influenza A virus cDNA fragments. A series of primers were synthesized on the basis of the comparison of hemagglutinin and PB2 gene sequences of different origin. RT-PCR reactions were run using these primers, products were denatured and single-strand DNA fragments were subjected to electrophoresis. After silver staining, ssDNA band patterns characteristic for each genotype were observed. Minor differences within a serotype were detected without need for sequencing the PCR products making the preliminary analysis of avian influenza isolates much faster.
Mol Cell Probes
PMID:Detection of changes in avian influenza genome fragments by multitemperature single-strand conformational polymorphism. 1895 20

The role of migratory birds in the movement of the highly pathogenic (HP) avian influenza H5N1 remains a subject of debate. Testing hypotheses regarding intercontinental movement of low pathogenic avian influenza (LPAI) viruses will help evaluate the potential that wild birds could carry Asian-origin strains of HP avian influenza to North America during migration. Previous North American assessments of LPAI genetic variation have found few Asian reassortment events. Here, we present results from whole-genome analyses of LPAI isolates collected in Alaska from the northern pintail (Anas acuta), a species that migrates between North America and Asia. Phylogenetic analyses confirmed the genetic divergence between Asian and North American strains of LPAI, but also suggested inter-continental virus exchange and at a higher frequency than previously documented. In 38 isolates from Alaska, nearly half (44.7%) had at least one gene segment more closely related to Asian than to North American strains of LPAI. Additionally, sequences of several Asian LPAI isolates from GenBank clustered more closely with North American northern pintail isolates than with other Asian origin viruses. Our data support the role of wild birds in the intercontinental transfer of influenza viruses, and reveal a higher degree of transfer in Alaska than elsewhere in North America.
Mol Ecol 2008 Nov
PMID:Genetic evidence of intercontinental movement of avian influenza in a migratory bird: the northern pintail (Anas acuta). 1914 Sep 89

Influenza virus remains a serious health threat, owing to its ability to evade immune surveillance through rapid genetic drift and reassortment. Here we used a human non-immune antibody phage-display library and the H5 hemagglutinin ectodomain to select ten neutralizing antibodies (nAbs) that were effective against all group 1 influenza viruses tested, including H5N1 'bird flu' and the H1N1 'Spanish flu'. The crystal structure of one such nAb bound to H5 shows that it blocks infection by inserting its heavy chain into a conserved pocket in the stem region, thus preventing membrane fusion. Nine of the nAbs employ the germline gene VH1-69, and all seem to use the same neutralizing mechanism. Our data further suggest that this region is recalcitrant to neutralization escape and that nAb-based immunotherapy is a promising strategy for broad-spectrum protection against seasonal and pandemic influenza viruses.
Nat Struct Mol Biol 2009 Mar
PMID:Structural and functional bases for broad-spectrum neutralization of avian and human influenza A viruses. 1923 64

The duck and chicken are important hosts of avian influenza virus (AIV) with distinctive responses to infection. Frequently, AIV infections in ducks are asymptomatic and long-lasting in contrast to the clinically apparent and transient infections observed in chickens. These differences may be due in part to the host response to AIV infection. Using real-time quantitative PCR, we examined the expression of immune-related genes in response to low pathogenic AIV H11N9 infection in peripheral blood mononuclear cells (PBMC) isolated from the blood of chickens and Pekin ducks. While chicken PBMC expressed IL-1beta and IL-6 at high levels similar to mammalian species, duck PBMC expression levels were minimal or unchanged. Similarly, duck IFN-beta expression was nearly unaffected, whereas chicken expression was highly upregulated. Chicken IFN-gamma was expressed to higher levels than duck IFN-gamma, while IFN-alpha was expressed similarly by both species. IL-2 was elevated early in infection in duck PBMC, but returned to baseline levels by the end of the experiment; in contrast, IL-2 was weakly induced in chicken PBMC at late time points. TLR-7 and MHC class I molecule expressions were conserved between species, whereas duck MHC class II expression was downregulated and chicken expression was unchanged. These results show distinct PBMC expression patterns of pro-inflammatory cytokines and IFNs between species. The differences in pro-inflammatory cytokine and IFN expression reflect the asymptomatic and lasting infection observed in ducks and the tendency towards clinical signs and rapid clearance seen in chickens. These results highlight important differences in the host response to AIV of two species thought to be critical in the genesis and maintenance of epidemic strains of AIV.
Mol Immunol 2009 May
PMID:Immune-related gene expression in response to H11N9 low pathogenic avian influenza virus infection in chicken and Pekin duck peripheral blood mononuclear cells. 1925 Jun 79

Highly pathogenic H5N1 avian influenza virus can infect humans and is currently the most deadly influenza virus that has crossed the species barrier. As of December 2007, the spread of H5N1 virus from human to human has been rare. Nobody can predict if H5N1 may cause a pandemic. However, the number of human cases is continuously increasing and changes in virulence and epidemiology have been detected. There are specific pathogenic features of H5N1 infection. In contrast to human-adapted influenza A strains, H5N1 preferentially infects cells of the lower respiratory tract and may spread to tissues outside the respiratory tract in humans. Moreover, H5N1 replication is prolonged in target organs and results in higher viral loads and increased tissue damage. These features will have to be considered for therapeutic protocols for H5N1 infection in humans. Rapid genetic and antigenic changes observed in H5N1 virus isolates represent a challenge for the development of vaccines. In the present review, current knowledge about epidemiology, virulence factors and pathology of H5N1 infections in humans are summarised and discussed. Moreover, the possible roles of anti-influenza drugs in the pandemic situation as well as the development of effective vaccines are subject of this overview.
Curr Mol Med 2009 Mar
PMID:Of chickens and men: avian influenza in humans. 1927 23

The influenza virus A/gull/Moscow/3100/2006 (H6N2) was isolated from gull feces within the precincts of Moscow in autumn 2006. The nucleotide sequence of the complete genome (GenBank, EU152234-EU152241) and genotype (K, G, D, 6B, F, 2D, F, 1E) for this virus were determined. Phylogenetic analysis suggests that the H6N2 virus derived by numerous reassortment between viruses that have been circulating among different birds in Europe since 1999 and in South-East Asia (NA gene) for last years. Migratory birds probably introduced some of these viruses from South-East Asia earlier. The strain A/gull/Moscow/3100/2006 is nonpathogenic for chicken embryos and mice and induces specific antibody production in mice. Similar to all avian influenza viruses A/gull/Moscow/3100/ 2006 it binds to Neu5Ac(2-3Gal receptors, but reveals higher affinity for fucosylated sialosugars (SLex) in contrast to the duck viruses, as was shown in receptor specificity assay and clarified due to modeling the accommodation of SLex into receptor binding site of duck and gull influenza virus hemagglutinin.
Mol Gen Mikrobiol Virusol 2009
PMID:[The study of the nonpathogenic influenza virus A/gull/Moscow/3100/2006 (H6N2) isolated in Moscow]. 1928 Sep 91

Hemagglutinin (HA) binds to sialylated glycans exposed on the host cell surface in the initial stage of avian influenza virus infection. It has been previously hypothesized that glycan topology plays a critical role in the human adaptation of avian flu viruses, such as the potentially pandemic H5N1. Comparative molecular dynamics studies are complementary to experimental techniques, including glycan microarray, to understand the mechanism of species-specificity switch better. The examined systems comprise explicitly solvated trimeric forms of avian H3, H5, and swine H9 in complex with avian and human glycan receptor analogues--LSTa (alpha-2,3-linked lactoseries tetrasaccharide a) and LSTc (alpha-2,6-linked lactoseries tetrasaccharide c), respectively. The glycans adopted distinct topological profiles with inducible torsional angles when bound to different HAs. The corresponding receptor binding domain amino acid contact profiles were also distinct. Avian H5 was able to accommodate LSTc in a tightly "folded umbrella"-like topology through interactions with all five sugar residues. After considering conformational entropy, the relative binding free-energy changes, calculated using the molecular mechanics-generalized Born surface area technique, were in agreement with previous experimental findings and provided insights on electrostatic, van der Waals, desolvation, and entropic contributions to HA-glycan interactions. The topology profile and the relative abundance of free glycan receptors may influence receptor binding kinetics. Glycan composition and topological changes upon binding different HAs may be important determinants in species-specificity switch.
J Mol Biol 2009 Mar 27
PMID:Distinct glycan topology for avian and human sialopentasaccharide receptor analogues upon binding different hemagglutinins: a molecular dynamics perspective. 1935 94


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