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Dengue is caused by a taxonomic group of four viruses, dengue virus types 1-4 (DENV1-DENV4). A molecular understanding of the antibody-mediated protection against this disease is critical to design safe vaccines and therapeutics. Here, the energetic epitope of antibody mAb4E11, which neutralizes the four serotypes of DENV but no other flavivirus, and binds domain 3 (ED3) of their envelope glycoprotein, was characterized. Alanine-scanning mutagenesis of the ED3 domain from serotype DENV1 was performed and the affinities between the mutant domains and the Fab fragment of mAb4E11 were measured. The epitope residues (307-312, 387, 389 and 391) were at the edges of two distinct b-sheets. Four residues constituted hot spots of binding energy. They were aliphatic and contributed to form a hydrophobic pocket (Leu308, Leu389), or were positively charged (Lys307, Lys310). They may bind the diversity residues of mAb4E11, H-Trp96-Glu97. Remarkably, cyclic residues occupy and block the hydrophobic pocket in all unrelated flaviviruses. Transplanting the epitope from the ED3 domain of DENV into those of other flaviviruses restored affinity. The epitope straddles residues of ED3 that are involved in virulence, e.g. Asn/Asp390. These results define the epitope of mAb4E11 as an antigenic signature of the DENV group and suggest mechanisms for its neutralization potency. INTRODUCTIONDengue is a re-emerging viral disease. It is caused by four types of virus, dengue virus types 1-4 (DENV1-DENV4), which belong to the species Dengue virus in the genus Flavivirus (Heinz et al., 2000). They are transmitted by Aedes mosquitoes and infect between 50 million and 100 million persons each year. The disease generally takes a mild form, dengue fever, but severe forms, dengue haemorragic fever and dengue shock syndrome, have recently become epidemic (Gubler, 2002).The immune response against an infection by DENV involves both a humoral component, in the form of neutralizing antibodies, and a cell-mediated component (Guzman & Kouri, 2002). The preferential reactivation of the memory B cells that correspond to a primary infection, and an antibody-dependent enhancement of infection, might constitute triggering mechanisms of the severe forms during a secondary infection by a different viral serotype (Halstead, 2003; Mongkolsapaya et al., 2003). A molecular understanding of the events that lead to antibody neutralization, enhancement or escape is critical to the development of efficient and secure vaccines and therapeutics. DENV1-DENV4 are enveloped RNA viruses, like all flaviviruses. The structures of the whole virus and of the envelope glycoprotein E (gpE) have been solved by electron cryomicroscopy and X-ray crystallography (Modis et al., 2003(Modis et al., , 2005 Zhang et al., 2003). Ninety dimers of gpE cover the surface of the virus. Each monomer comprises three ectodomains, ED1-ED3, and a transmembrane segment. ED2 includes the dimerization interface, a glycosylation site and the peptide of fusion with the cellular membrane. ED3 is continuou...

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this study suggests that in people with type 2 diabetes, fatty liver is not associated with cardiovascular disease. In a diabetic population, it seems that fatty liver is not a determinant factor associated with carotid IMT.

We sought to examine ADAR-1 editing of measles and influenza virus genomes derived from inactivated seasonal influenza and live attenuated measles virus vaccines grown on chicken cells as the culture substrate. Using highly sensitive 3DI-PCR (R. Suspène et al., Nucleic Acids Res. 36:e72, 2008), it was possible to show that ADAR-1 could hyperdeaminate adenosine residues in both measles virus and influenza virus A genomes. Detailed analysis of the dinucleotide editing context showed preferences for 5ArA and 5UrA, which is typical of editing in mammalian cells. The hyperedited mutant frequency, including genomes and antigenomes, was a log greater for influenza virus compared to measles virus, suggesting a greater sensitivity to restriction by ADAR-1.

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Metabolic adaptations and changes in the expression of nutrient transporters are known to accompany tumorigenic processes. Nevertheless, in the context of solid tumors, studies of metabolism are hindered by a paucity of tools allowing the identification of cell surface transporters on individual cells. Here, we developed a method for the dissociation of human breast cancer tumor xenografts combined with quantification of cell surface markers, including metabolite transporters. The expression profiles of four relevant nutrient transporters for cancer cells' metabolism, Glut1, ASCT2, PiT1 and PiT2 (participating to glucose, glutamine and inorganic phosphate, respectively), as detected by new retroviral envelope glycoprotein-derived ligands, were distinctive of each tumor, unveiling underlying differences in metabolic pathways. Our tumor dissociation procedure and nutrient transporter profiling technology provides opportunities for future basic research, clinical diagnosis, prognosis and evaluation of therapeutic responses, as well as for drug discovery and development. Markers of tumor cell metabolism are of valuable importance for basic and clinical cancer research. The identification of metabolic alterations that accompany cancer processes is becoming critical for refining the clinical evaluation and treatment of patients, 1,2 as well as for further drug discovery and development. While metabolomics relies mainly on the quantification of anabolic and catabolic end products, 3 the bidirectional fluxes of nutrients and metabolites, as well as the efflux of toxins and pharmaceutical compounds, are ensured by nutrient transporters. 4 However, the monitoring of metabolite and nutrient transporters at the cell surface has been hampered by the paucity, if not total lack, of exofacial antibodies to such transporters. 5,6 Cell entry of gamma-and deltaretroviruses occurs via recognition of membrane metabolite transporters by retroviral envelope glycoproteins (Env). 7,8 Viral entry occurs following the specific binding of the amino-terminal receptor binding domain (RBD) of an individual Env with its cognate receptor. We designed RBD probes, derived from gamma-and deltaretroviral Env, as specific ligands that bind to these cell surface transporters. Binding of defined ligands allows the quantification of distinct sets of metabolite transporters at the cell surface. 9-13 Furthermore, while cell surface labeling is readily achieved on cultured cell lines and circulating hematopoietic cells, singlecell labeling of solid tumors has remained problematic. Indeed, such analyses require dissociation methods that yield