36 research outputs found

    Characterization of human cytomegalovirus genome diversity in immunocompromised hosts by whole genomic sequencing directly from clinical specimens

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    Background: Advances in next-generation sequencing (NGS) technologies allow comprehensive studies of genetic diversity over the entire genome of human cytomegalovirus (HCMV), a significant pathogen for immunocompromised individuals. Methods: NGS was performed on target-enriched sequence libraries prepared directly from a variety of clinical specimens (blood, urine, breast-milk, respiratory samples, biopsies and vitreous humor) obtained longitudinally or from different anatomical compartments from 20 HCMV-infected patients (renal transplant recipients, stem cell transplant recipients and congenitally infected children). Results: De novo assembled HCMV genome sequences were obtained for 57/68 sequenced samples. Analysis of longitudinal or compartmental HCMV diversity revealed various patterns: no major differences were detected among longitudinal, intra-individual blood samples from 9/15 patients and in most of the patients with compartmental samples, whereas a switch of the major HCMV population was observed in six individuals with sequential blood samples and upon compartmental analysis of one patient with HCMV retinitis. Variant analysis revealed additional aspects of minor virus population dynamics and antiviral resistance mutations. Conclusions: In immunosuppressed patients, HCMV can remain relatively stable or undergo drastic genomic changes that are suggestive of the emergence of minor resident strains or de novo infection

    Early replication in pulmonary B cells after infection with marek's disease herpesvirus by the respiratory route

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    Natural infection with Marek's disease virus occurs through the respiratory mucosa after chickens inhale dander shed from infected chickens. The early events in the lung following exposure to the feather and squamous epithelial cell debris containing the viral particles remain unclear. In order to elucidate the virological and immunological consequences of MDV infection for the respiratory tract, chickens were infected by intratracheal administration of infective dander. Differences between susceptible and resistant chickens were immediately apparent, with delayed viral replication and earlier onset of interferon (IFN)-γ production in the latter. CD4+ and CD8 + T cells surrounded infected cells in the lung. Although viral replication was evident in macrophages, pulmonary B cells were the main target cell type in susceptible chickens following intratracheal infection with MDV. In accordance, depletion of B cells curtailed viremia and substantially affected pathogenesis in susceptible chickens. Together the data described here demonstrate the role of pulmonary B cells as the primary and predominant target cells and their importance for MDV pathogenesis. © 2009, Mary Ann Liebert, Inc.

    Thresholds for adding degraded tropical forest to the conservation estate

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    Logged and disturbed forests are often viewed as degraded and depauperate environments compared with primary forest. However, they are dynamic ecosystems1 that provide refugia for large amounts of biodiversity2,3, so we cannot afford to underestimate their conservation value4. Here we present empirically defined thresholds for categorizing the conservation value of logged forests, using one of the most comprehensive assessments of taxon responses to habitat degradation in any tropical forest environment. We analysed the impact of logging intensity on the individual occurrence patterns of 1,681 taxa belonging to 86 taxonomic orders and 126 functional groups in Sabah, Malaysia. Our results demonstrate the existence of two conservation-relevant thresholds. First, lightly logged forests (68%) of their biomass removed, and these are likely to require more expensive measures to recover their biodiversity value. Overall, our data confirm that primary forests are irreplaceable5, but they also reinforce the message that logged forests retain considerable conservation value that should not be overlooked

    Monoclonal and polyclonal antibodies to chicken immunoglobulin isotypes specifically detect turkey immunoglobulin isotypes6196

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    Turkey immunoglobulin (Ig) isotypes IgG and IgM were isolated from blood and IgA was isolated from bile. Isolation was accomplished by gel filtration of the ammonium sulphate cut on Sephacryl S-200. Using immunoelectrophoresis and indirect ELISA, the cross-reactivity between antibodies, of monoclonal and polyclonal origin, specific for the Ig isotypes of chicken, and the purified turkey Ig isotypes was evaluated. Commercially available polyclonal antibodies, anti-chicken/IgA (alpha-chain specific, affinity purified), anti-chicken/IgG (Fc-fragment specific) and anti-chicken/IgM (mu-chain specific) showed an interspecies cross-reactivity with the corresponding turkey Ig isotypes. The monoclonal antibody (MAb) AV-G3 specifically detected turkey IgG, whereas MAb M1 reacted exclusively with turkey IgM. This panel of anti-immunoglobulins represents a useful tool for examining the humoral immune responses of turkeys</p

    Recombination in human herpesvirus-8 strains from Uganda and evolution of the K15 gene

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    Human herpesvirus-8 (HHV-8) is believed to be the aetiological agent of Kaposi's sarcoma (KS). KS accounts for half the reported cancer cases in Uganda, and occurs in endemic and epidemic [human immunodeficiency virus (HIV)-associated] forms. We confirmed a high prevalence (74%) of HHV-8 antibodies in 114 HIV-negative Ugandan blood donors, and characterized the genomes of HHV-8 strains present in 30 adult Ugandan KS patients. Phylogenetic analysis of the uniquely variable K1 gene indicated that the majority of KS patients were infected by the B subtype of HHV-8, several by the A5 subtype, and one by a variant of the C subtype. Sequence analysis of nine strains at several other genome loci spaced out across the genome indicated that five are recombinants between subtypes when considered independently of previously published definitions of parental (unrecombined) genotypes. When previously published parental genotypes were taken into account, seven of the nine strains appeared to be recombinants. Analysis of the K15 gene, which exists in HHV-8 in two highly diverged alleles, indicated that the P allele predominates, with only a single strain bearing the M allele. Divergence between the M allele in the latter strain and that in the previously sequenced BC1 strain is at least as great as that between representatives of the P allele. This indicates that introduction of the M allele into extant HHV-8 subtypes did not occur by a single, relatively recent recombination event as was concluded from a previous study in which very limited variation in the M allele was reported
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