Comparable fitness and transmissibility between oseltamivir-resistant pandemic 2009 and seasonal H1N1 influenza viruses with the H275Y neuraminidase mutation

Limited antiviral compounds are available for the control of influenza, and the emergence of resistant variants would further narrow the options for defense. The H275Y neuraminidase (NA) mutation, which confers resistance to oseltamivir carboxylate, has been identified among the seasonal H1N1 and 2009 pandemic influenza viruses; however, those H275Y resistant variants demonstrated distinct epidemiological outcomes in humans. Specifically, dominance of the H275Y variant over the oseltamivir-sensitive viruses was only reported for a seasonal H1N1 variant during 2008-2009. Here, we systematically analyze the effect of the H275Y NA mutation on viral fitness and transmissibility of A(H1N1)pdm09 and seasonal H1N1 influenza viruses. The NA genes from A(H1N1)pdm09 A/California/04/09 (CA04), seasonal H1N1 A/New Caledonia/20/1999 (NewCal), and A/Brisbane/59/2007 (Brisbane) were individually introduced into the genetic background of CA04. The H275Y mutation led to reduced NA enzyme activity, an increased K(m) for 3'-sialylactose or 6'-sialylactose, and decreased infectivity in mucin-secreting human airway epithelial cells compared to the oseltamivir-sensitive wild-type counterparts. Attenuated pathogenicity in both RG-CA04(NA-H275Y) and RG-CA04 x Brisbane(NA-H275Y) viruses was observed in ferrets compared to RG-CA04 virus, although the transmissibility was minimally affected. In parallel experiments using recombinant Brisbane viruses differing by hemagglutinin and NA, comparable direct contact and respiratory droplet transmissibilities were observed among RG-NewCal(HA,NA), RG-NewCal(HA,NA-H275Y), RG-Brisbane(HA,NA-H275Y), and RG-NewCal(HA) x Brisbane(NA-H275Y) viruses. Our results demonstrate that, despite the H275Y mutation leading to a minor reduction in viral fitness, the transmission potentials of three different antigenic strains carrying this mutation were comparable in the naive ferret model.published_or_final_versio

Comparable fitness and transmissibility between Oseltamivir-Resistant Pandemic 2009 and seasonal H1N1 Influenza Viruses with the H275Y Neuraminidase Mutation

Conference Theme: Translating Health Research into Policy and Practice for Health of the PopulationPoster Presentations - Emerging / Infectious Diseases: no. P65-Ab0010INTRODUCTION: Neuraminidase (NA) inhibitors are one of the limited options for the control of influenza. The H275Y NA mutation, which confers resistance to oseltamivir carboxylate, was initially considered to be of little clinical consequence due to limited detection of this mutation in field isolates prior to 2007-2008, when a globally spreading H275Y variant emerged. Oseltamivir-resistant A(H1N1)pdm09 viruses with the H275Y NA mutation has been reported since 2009 but have not replaced the …published_or_final_versio

CLEC5A-mediated enhancement of the inflammatory response in myeloid cells contributes to influenza virus pathogenicity in vivo

Human infections with influenza viruses exhibit mild to severe clinical outcomes as a result of complex virus-host interactions. Induction of inflammatory mediators via pattern recognition receptors may dictate subsequent host responses for pathogen clearance and tissue damage. We identified that human C-type lectin domain family 5 member A (CLEC5A) interacts with the hemagglutinin protein of influenza viruses expressed on lentiviral pseudoparticles through lectin screening. Silencing CLEC5A gene expression, blocking influenza-CLEC5A interactions with anti-CLEC5A antibodies, or dampening CLEC5A-mediated signaling using a spleen tyrosine kinase inhibitor consistently reduced the levels of proinflammatory cytokines produced by human macrophages without affecting the replication of influenza A viruses of different subtypes. Infection of bone marrow-derived macrophages from CLEC5A-deficient mice showed reduced levels of tumor necrosis factor alpha (TNF-α) and IP-10 but elevated alpha interferon (IFN-α) compared to those of wild-type mice. The heightened type I IFN response in the macrophages of CLEC5A-deficient mice was associated with upregulated TLR3 mRNA after treatment with double-stranded RNA. Upon lethal challenges with a recombinant H5N1 virus, CLEC5A-deficient mice showed reduced levels of proinflammatory cytokines, decreased immune cell infiltration in the lungs, and improved survival compared to the wild-type mice, despite comparable viral loads noted throughout the course of infection. The survival difference was more prominent at a lower dose of inoculum. Our results suggest that CLEC5A-mediated enhancement of the inflammatory response in myeloid cells contributes to influenza pathogenicity in vivo and may be considered a therapeutic target in combination with effective antivirals. Well-orchestrated host responses together with effective viral clearance are critical for optimal clinical outcome after influenza infections.published_or_final_versio

Prevalence and Correlates of Common Mental Disorders among Mothers of Young Children in Kilimanjaro Region of Tanzania.

Although poor maternal mental health is a major public health problem, with detrimental effects on the individual, her children and society, information on its correlates in low-income countries is sparse. This study investigates the prevalence of common mental disorders (CMD) among at-risk mothers, and explores its associations with sociodemographic factors. This population-based survey of mothers of children aged 0-36 months used the 14-item Shona Symptom Questionnaire (SSQ). Mothers whose response was "yes" to 8 or more items on the scale were defined as "at risk of CMD." Of the 1,922 mothers (15-48 years), 28.8% were at risk of CMD. Risk of CMD was associated with verbal abuse, physical abuse, a partner who did not help with the care of the child, being in a polygamous relationship, a partner with low levels of education, and a partner who smoked cigarettes. Cohabiting appeared to be protective. Taken together, our results indicate the significance of the quality of relations with one's partner in shaping maternal mental health. The high proportion of mothers who are at risk of CMD emphasizes the importance of developing evidence-based mental health programmes as part of the care package aimed at improving maternal well-being in Tanzania and other similar settings

Representativeness of microsatellite distributions in genomes, as revealed by 454 GS-FLX Titanium pyrosequencing

<p>Abstract</p> <p>Background</p> <p>Microsatellites are markers of choice in population genetics and genomics, as they provide useful insight into patterns and processes as diverse as genome evolutionary dynamics and demographic processes. The acquisition of microsatellites through multiplex-enriched libraries and 454 GS-FLX Titanium pyrosequencing is a promising new tool for the isolation of new markers in unknown genomes. This approach can also be used to evaluate the extent to which microsatellite-enriched libraries are representative of the genome from which they were isolated. In this study, we deciphered potential discrepancies in microsatellite content recovery for two reference genomes (<it>Apis mellifera </it>and <it>Danio rerio</it>), selected on the basis of their extreme heterogeneity in terms of the proportions and distributions of microsatellites on chromosomes.</p> <p>Results</p> <p>The <it>A. mellifera </it>genome, in particular, was found to be highly heterogeneous, due to extremely high rates of recombination, with hotspots, but the only bias consistently introduced into pyrosequenced multiplex-enriched libraries concerned sequence length, with the overrepresentation of sequences 160 to 320 bp in length. Other deviations from expected proportions or distributions of motifs on chromosomes were observed, but the significance and intensity of these deviations was mostly limited. Furthermore, no consistent adverse competition between multiplexed probes was observed during the motif enrichment phase.</p> <p>Conclusions</p> <p>This approach therefore appears to be a promising strategy for improving the development of microsatellites, as it introduces no major bias in terms of the proportions and distribution of microsatellites.</p

Allelic Exchange of Pheromones and Their Receptors Reprograms Sexual Identity in Cryptococcus neoformans

Cell type specification is a fundamental process that all cells must carry out to ensure appropriate behaviors in response to environmental stimuli. In fungi, cell identity is critical for defining “sexes” known as mating types and is controlled by components of mating type (MAT) loci. MAT–encoded genes function to define sexes via two distinct paradigms: 1) by controlling transcription of components common to both sexes, or 2) by expressing specially encoded factors (pheromones and their receptors) that differ between mating types. The human fungal pathogen Cryptococcus neoformans has two mating types (a and α) that are specified by an extremely unusual MAT locus. The complex architecture of this locus makes it impossible to predict which paradigm governs mating type. To identify the mechanism by which the C. neoformans sexes are determined, we created strains in which the pheromone and pheromone receptor from one mating type (a) replaced the pheromone and pheromone receptor of the other (α). We discovered that these “αa” cells effectively adopt a new mating type (that of a cells); they sense and respond to α factor, they elicit a mating response from α cells, and they fuse with α cells. In addition, αa cells lose the α cell type-specific response to pheromone and do not form germ tubes, instead remaining spherical like a cells. Finally, we discovered that exogenous expression of the diploid/dikaryon-specific transcription factor Sxi2a could then promote complete sexual development in crosses between α and αa strains. These data reveal that cell identity in C. neoformans is controlled fully by three kinds of MAT–encoded proteins: pheromones, pheromone receptors, and homeodomain proteins. Our findings establish the mechanisms for maintenance of distinct cell types and subsequent developmental behaviors in this unusual human fungal pathogen

The Biochemistry, Ultrastructure, and Subunit Assembly Mechanism of AMPA Receptors

The AMPA-type ionotropic glutamate receptors (AMPA-Rs) are tetrameric ligand-gated ion channels that play crucial roles in synaptic transmission and plasticity. Our knowledge about the ultrastructure and subunit assembly mechanisms of intact AMPA-Rs was very limited. However, the new studies using single particle EM and X-ray crystallography are revealing important insights. For example, the tetrameric crystal structure of the GluA2cryst construct provided the atomic view of the intact receptor. In addition, the single particle EM structures of the subunit assembly intermediates revealed the conformational requirement for the dimer-to-tetramer transition during the maturation of AMPA-Rs. These new data in the field provide new models and interpretations. In the brain, the native AMPA-R complexes contain auxiliary subunits that influence subunit assembly, gating, and trafficking of the AMPA-Rs. Understanding the mechanisms of the auxiliary subunits will become increasingly important to precisely describe the function of AMPA-Rs in the brain. The AMPA-R proteomics studies continuously reveal a previously unexpected degree of molecular heterogeneity of the complex. Because the AMPA-Rs are important drug targets for treating various neurological and psychiatric diseases, it is likely that these new native complexes will require detailed mechanistic analysis in the future. The current ultrastructural data on the receptors and the receptor-expressing stable cell lines that were developed during the course of these studies are useful resources for high throughput drug screening and further drug designing. Moreover, we are getting closer to understanding the precise mechanisms of AMPA-R-mediated synaptic plasticity

ICAR: endoscopic skull‐base surgery

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A new era for understanding amyloid structures and disease

The aggregation of proteins into amyloid fibrils and their deposition into plaques and intracellular inclusions is the hallmark of amyloid disease. The accumulation and deposition of amyloid fibrils, collectively known as amyloidosis, is associated with many pathological conditions that can be associated with ageing, such as Alzheimer disease, Parkinson disease, type II diabetes and dialysis-related amyloidosis. However, elucidation of the atomic structure of amyloid fibrils formed from their intact protein precursors and how fibril formation relates to disease has remained elusive. Recent advances in structural biology techniques, including cryo-electron microscopy and solid-state NMR spectroscopy, have finally broken this impasse. The first near-atomic-resolution structures of amyloid fibrils formed in vitro, seeded from plaque material and analysed directly ex vivo are now available. The results reveal cross-β structures that are far more intricate than anticipated. Here, we describe these structures, highlighting their similarities and differences, and the basis for their toxicity. We discuss how amyloid structure may affect the ability of fibrils to spread to different sites in the cell and between organisms in a prion-like manner, along with their roles in disease. These molecular insights will aid in understanding the development and spread of amyloid diseases and are inspiring new strategies for therapeutic intervention