Conformational Reorganization of the SARS Coronavirus Spike Following Receptor Binding: Implications for Membrane Fusion

The SARS coronavirus (SARS-CoV) spike is the largest known viral spike molecule, and shares a similar function with all class 1 viral fusion proteins. Previous structural studies of membrane fusion proteins have largely used crystallography of static molecular fragments, in isolation of their transmembrane domains. In this study we have produced purified, irradiated SARS-CoV virions that retain their morphology, and are fusogenic in cell culture. We used cryo-electron microscopy and image processing to investigate conformational changes that occur in the entire spike of intact virions when they bind to the viral receptor, angiotensin-converting enzyme 2 (ACE2). We have shown that ACE2 binding results in structural changes that appear to be the initial step in viral membrane fusion, and precisely localized the receptor-binding and fusion core domains within the entire spike. Furthermore, our results show that receptor binding and subsequent membrane fusion are distinct steps, and that each spike can bind up to three ACE2 molecules. The SARS-CoV spike provides an ideal model system to study receptor binding and membrane fusion in the native state, employing cryo-electron microscopy and single-particle image analysis

Imaging Single Retrovirus Entry through Alternative Receptor Isoforms and Intermediates of Virus-Endosome Fusion

A large group of viruses rely on low pH to activate their fusion proteins that merge the viral envelope with an endosomal membrane, releasing the viral nucleocapsid. A critical barrier to understanding these events has been the lack of approaches to study virus-cell membrane fusion within acidic endosomes, the natural sites of virus nucleocapsid capsid entry into the cytosol. Here we have investigated these events using the highly tractable subgroup A avian sarcoma and leukosis virus envelope glycoprotein (EnvA)-TVA receptor system. Through labeling EnvA pseudotyped viruses with a pH-sensitive fluorescent marker, we imaged their entry into mildly acidic compartments. We found that cells expressing the transmembrane receptor (TVA950) internalized the virus much faster than those expressing the GPI-anchored receptor isoform (TVA800). Surprisingly, TVA800 did not accelerate virus uptake compared to cells lacking the receptor. Subsequent steps of virus entry were visualized by incorporating a small viral content marker that was released into the cytosol as a result of fusion. EnvA-dependent fusion with TVA800-expressing cells occurred shortly after endocytosis and delivery into acidic endosomes, whereas fusion of viruses internalized through TVA950 was delayed. In the latter case, a relatively stable hemifusion-like intermediate preceded the fusion pore opening. The apparent size and stability of nascent fusion pores depended on the TVA isoforms and their expression levels, with TVA950 supporting more robust pores and a higher efficiency of infection compared to TVA800. These results demonstrate that surface receptor density and the intracellular trafficking pathway used are important determinants of efficient EnvA-mediated membrane fusion, and suggest that early fusion intermediates play a critical role in establishing low pH-dependent virus entry from within acidic endosomes

The Association of Systemic Microvascular Changes with Lung Function and Lung Density: A Cross-Sectional Study

10.1371/journal.pone.0050224PLoS ONE712

Narrativas na Formação do Professor de Matemática: o caso da professora Atíria

Neste artigo exploraremos as potencialidades das narrativas na Educação Matemática como um modo de relatar, representar e refletir uma experiência. Particularmente, procuraremos desvelar como a construção de narrativas escritas, por uma professora em formação continuada, constituiu-se em um importante processo de desenvolvimento profissional da mesma, durante a proposição e implementação de uma metodologia investigativa de ensino de Matemática, em uma sala de aula considerada desafiadora na escola pública. Os resultados evidenciam que, com as trocas entre os pares pesquisadores, a professora inseriu novas reflexões (na ação e sobre a ação) em sua experiência pedagógica, registrando-as para ações futuras com o uso das investigações matemáticas, despertando-lhe possibilidades de outras aprendizagens, através da perspectiva de novas propostas de sequências didáticas significativas para os alunos e que sejam factíveis para as salas de aula reais e complexas que encontramos na escola pública de hoje. Consideramos que o uso de narrativas proporcionou-lhe uma formação continuada que levou em conta as questões culturais escolares mais amplas, seus saberes docentes e experiências anteriores, superando as concepções de formação clássica

Análise crítica da Carta Brasileira de Prevenção Integrada na Área da Saúde na Perspectiva da Educação Física através do enfoque radical de promoção da saúde

O presente trabalho pretende contribuir para que a área profissional e o campo do saber referente à Educação Física apreendam a saúde de forma ampliada, superando o enfoque biologicista hegemônico. Possui caráter qualitativo e baseou-se em pesquisa de fontes bibliográficas para a confecção de monografia de conclusão do curso de especialização em Saúde Pública, na Escola Nacional de Saúde Pública Sergio Arouca da Fundação Oswaldo Cruz. Analisou-se criticamente a Carta Brasileira de Prevenção Integrada na área da Saúde na perspectiva da Educação Física - publicação do Conselho Federal de Educação Física (CONFEF), em 2006, a partir do enfoque radical da Promoção da Saúde. Esse enfoque pode ser sintetizado na proposta de articulação entre saúde e condições de vida, ressaltando as inter-relações de equidade social, através do aumento da capacidade da participação popular, intersetorialidade, fomento de políticas públicas saudáveis, criação de ambientes favoráveis à saúde e reorientação do sistema de saúde, baseando-se numa visão ampliada do processo saúde-doença e reconhecendo a multideterminação desse processo (OMS, 1986; Buss, 2000, 2001, 2007; Pedrosa, 2004). Concluiu-se que o documento analisado biologiza e medicaliza a Educação Física em sua relação com a sociedade. Recomenda-se que o mesmo seja revisto a partir da perspectiva crítica ligada à área da Educação Física, a qual relaciona a atividade física e a saúde com questões sociais mais amplas que impedem que os sujeitos tomem decisões mais saudáveis, tais como os condicionantes econômicos, culturais, étnicos e políticos.This work intends to provide a contribution so that the professional area and the field of knowledge referring to Physical Education view health in a broader way, overcoming the biological focus which usually occurs. It has a qualitative character and was based on research into bibliographic sources in order to develop a monograph upon the completion of the Public Health specialization course at the National School of Public Health Sergio Arouca, of the Oswaldo Cruz Foundation. The Brazilian Charter of Integrated Prevention in the Field of Health in the Perspective of Physical Education, a document written by the Federal Council of Physical Education (CONFEF) in 2006, was critically analyzed based on the radical focus of Health Promotion. This focus can be summarized as an articulation between health and life conditions, emphasizing social equity interrelations, through the increase in the capacity for popular participation, intersectoriality, promotion of healthy public policies, creation of environments that are favorable to health, and through a reorientation of the health system, based on a broader view of the health-disease process and on the recognition of the multi-determination of this process (OMS, 1986; Buss, 2000, 2001, 2007; Pedrosa, 2004). We concluded that the document that we analyzed assumes a biological and medical view concerning the relation between Physical Education and society. We recommend that this document is revised based on the critical perspective connected with the Physical Education field, which relates physical activities and health to broader social issues which prevent subjects from making healthier decisions, such as economic, cultural, ethnic and political conditioning factors

Mycobacterium tuberculosis epitope-specific interferon-g production in healthy Brazilians reactive and non-reactive to tuberculin skin test

The interferon (IFN)-gamma response to peptides can be a useful diagnostic marker of Mycobacterium tuberculosis (MTB) latent infection. We identified promiscuous and potentially protective CD4(+) T-cell epitopes from the most conserved regions of MTB antigenic proteins by scanning the MTB antigenic proteins GroEL2, phosphate-binding protein 1 precursor and 19 kDa antigen with the TEPITOPE algorithm. Seven peptide sequences predicted to bind to multiple human leukocyte antigen (HLA)-DR molecules were synthesised and tested with IFN-gamma enzyme-linked immunospot (ELISPOT) assays using peripheral blood mononuclear cells (PBMCs) from 16 Mantoux tuberculin skin test (TST)-positive and 16 TST-negative healthy donors. Eighty-eight percent of TST-positive donors responded to at least one of the peptides, compared to 25% of TST-negative donors. Each individual peptide induced IFN-gamma production by PBMCs from at least 31% of the TST-positive donors. the magnitude of the response against all peptides was 182 +/- 230 x 10(6) IFN-gamma spot forming cells (SFC) among TST-positive donors and 36 +/- 62 x 10(6) SFC among TST-negative donors (p = 0.007). the response to GroEL2 (463-477) was only observed in the TST-positive group. This combination of novel MTB CD4 T-cell epitopes should be tested in a larger cohort of individuals with latent tuberculosis (TB) to evaluate its potential to diagnose latent TB and it may be included in ELISPOT-based IFN-gamma assays to identify individuals with this condition.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Fac Med, Inst Coracao, Immunol Lab, São Paulo, BrazilUniversidade Federal de São Paulo, Fac Med, Dept Med, Div Imunol Clin & Alergia, São Paulo, BrazilFundacao Oswaldo Cruz, Lab Avancado Saude Publ, Salvador, BA, BrazilEscola Bahiana Med & Saude Publ, Salvador, BA, BrazilInst Invest Immunol, São Paulo, BrazilUniversidade Federal de São Paulo, Fac Med, Inst Coracao, Immunol Lab, São Paulo, BrazilUniversidade Federal de São Paulo, Fac Med, Dept Med, Div Imunol Clin & Alergia, São Paulo, BrazilWeb of Scienc