Fundación Instituto Leloir

About: Fundación Instituto Leloir is a facility organization based out in Buenos Aires, Argentina. It is known for research contribution in the topics: Dentate gyrus & Neurogenesis. The organization has 702 authors who have published 1052 publications receiving 39299 citations.

Protection induced by a glycoprotein E-deleted bovine herpesvirus type 1 marker strain used either as an inactivated or live attenuated vaccine in cattle.

Abstract: Background Bovine herpesvirus type 1 (BoHV-1) is the causative agent of respiratory and genital tract infections; causing a high economic loss in all continents. Use of marker vaccines in IBR eradication programs is widely accepted since it allows for protection of the animals against the disease while adding the possibility of differentiating vaccinated from infected animals. The aim of the present study was the development and evaluation of safety and efficacy of a glycoprotein E-deleted (gE-) BoHV-1 marker vaccine strain (BoHV-1ΔgEβgal) generated by homologous recombination, replacing the viral gE gene with the β-galactosidase (βgal) gene.

Zika Virus Subgenomic Flavivirus RNA Generation Requires Cooperativity between Duplicated RNA Structures That Are Essential for Productive Infection in Human Cells.

Abstract: Zika virus (ZIKV) is an emerging flavivirus, mainly transmitted by mosquitoes, which represents a global health threat A common feature of flavivirus-infected cells is the accumulation of viral noncoding subgenomic RNAs by partial degradation of the viral genome, known as sfRNAs, involved in immune evasion and pathogenesis Although great effort is being made to understand the mechanism by which these sfRNAs function during infection, the picture of how they work is still incomplete In this study, we developed new genetic tools to dissect the functions of ZIKV RNA structures for viral replication and sfRNA production in mosquito and human hosts ZIKV infections mostly accumulate two kinds of sfRNAs, sfRNA1 and sfRNA2, by stalling genome degradation upstream of duplicated stem loops (SLI and SLII) of the viral 3' untranslated region (UTR) Although the two SLs share conserved sequences and structures, different functions have been found for ZIKV replication in human and mosquito cells While both SLs are enhancers for viral infection in human cells, they play opposite roles in the mosquito host The dissection of determinants for sfRNA formation indicated a strong cooperativity between SLI and SLII, supporting a high-order organization of this region of the 3' UTR Using recombinant ZIKV with different SLI and SLII arrangements, which produce different types of sfRNAs or lack the ability to generate these molecules, revealed that at least one sfRNA was necessary for efficient infection and transmission in Aedes aegypti mosquitoes Importantly, we demonstrate an absolute requirement of sfRNAs for ZIKV propagation in human cells In this regard, viruses lacking sfRNAs, constructed by deletion of the region containing SLI and SLII, were able to infect human cells but the infection was rapidly cleared by antiviral responses Our findings are unique for ZIKV, since in previous studies, other flaviviruses with deletions of analogous regions of the genome, including dengue and West Nile viruses, accumulated distinct species of sfRNAs and were infectious in human cells We conclude that flaviviruses share common strategies for sfRNA generation, but they have evolved mechanisms to produce different kinds of these RNAs to accomplish virus-specific functionsIMPORTANCE Flaviviruses are important emerging and reemerging human pathogens Understanding the molecular mechanisms for viral replication and evasion of host antiviral responses is relevant to development of control strategies Flavivirus infections produce viral noncoding RNAs, known as sfRNAs, involved in viral replication and pathogenesis In this study, we dissected molecular determinants for Zika virus sfRNA generation in the two natural hosts, human cells and mosquitoes We found that two RNA structures of the viral 3' UTR operate in a cooperative manner to produce two species of sfRNAs and that the deletion of these elements has a profoundly different impact on viral replication in the two hosts Generation of at least one sfRNA was necessary for efficient Zika virus infection of Aedes aegypti mosquitoes Moreover, recombinant viruses with different 3' UTR arrangements revealed an essential role of sfRNAs for productive infection in human cells In summary, we define molecular requirements for Zika virus sfRNA accumulation and provide new ideas of how flavivirus RNA structures have evolved to succeed in different hosts

Ligand binding promiscuity of human liver fatty acid binding protein: structural and dynamic insights from an interaction study with glycocholate and oleate.

Abstract: Human liver fatty acid binding protein (hL-FABP) has been reported to act as an intracellular shuttle of lipid molecules, thus playing a central role in systemic metabolic homeostasis. The involvement of hL-FABP in the transport of bile salts has been postulated but scarcely investigated. Here we describe a thorough NMR investigation of glycocholate (GCA) binding to hL-FABP. The protein molecule bound a single molecule of GCA, in contrast to the 1:2 stoichiometry observed with fatty acids. GCA was found to occupy the large internal cavity of hL-FABP, without requiring major conformational rearrangement of the protein backbone; rather, this led to increased stability, similar to that estimated for the hL-FABP:oleate complex. Fast-timescale dynamics appeared not to be significantly perturbed in the presence of ligands. Slow motions (unlike for other proteins of the family) were retained or enhanced upon binding, consistent with a requirement for structural plasticity for promiscuous recognition.

Sequence Evolution of the Intrinsically Disordered and Globular Domains of a Model Viral Oncoprotein

Abstract: In the present work, we have used the papillomavirus E7 oncoprotein to pursue structure-function and evolutionary studies that take into account intrinsic disorder and the conformational diversity of globular domains. The intrinsically disordered (E7N) and globular (E7C) domains of E7 show similar degrees of conservation and co-evolution. We found that E7N can be described in terms of conserved and coevolving linear motifs separated by variable linkers, while sequence evolution of E7C is compatible with the known homodimeric structure yet suggests other activities for the domain. Within E7N, inter-residue relationships such as residue co-evolution and restricted intermotif distances map functional coupling and co-occurrence of linear motifs that evolve in a coordinate manner. Within E7C, additional cysteine residues proximal to the zinc-binding site may allow redox regulation of E7 function. Moreover, we describe a conserved binding site for disordered domains on the surface of E7C and suggest a putative target linear motif. Both homodimerization and peptide binding activities of E7C are also present in the distantly related host PHD domains, showing that these two proteins share not only structural homology but also functional similarities, and strengthening the view that they evolved from a common ancestor. Finally, we integrate the multiple activities and conformations of E7 into a hierarchy of structure-function relationships.

High-risk HPV E6 oncoproteins assemble into large oligomers that allow localization of endogenous species in prototypic HPV-transformed cell lines.

Abstract: The E6 oncoproteins of high-risk HPV types 16 and 18 are involved in the development of cervical cancer. Besides its determinant role in carcinogenic progression, HPV E6 oncoprotein has also been instrumental in elucidating fundamental aspects of p53 function and its ubiquitin-proteasome degradation, with counterpart activities in various DNA tumor viruses. Establishing the conformational state and cellular distribution unequivocally for the endogenous protein in HPV-transformed cell lines derived from carcinomas is essential for understanding the underlying mechanism. Recombinant E6 from high-risk strains 16 and 18 folds into soluble oligomers of approximately 1.2 MDa, which are thermostable and display cooperative loss of tertiary and secondary structure upon chemical denaturation. Antibodies raised against these assemblies locate E6 evenly distributed in the cells. By depleting the polyclonal serum by immunoblocking with monomeric E6, the nuclei of Hela and CaSki cells become completely devoid of label, indicating that monomeric species are mainly localized in the nucleus and that both monomers and oligomers share epitopes. The monomeric species promote degradation of p53 by the proteasome, which correlates with the nuclear localization we describe. In contrast, the oligomeric E6 does not promote p53 degradation, in agreement with its cytoplasmic localization inferred from the immunoneutralization experiments. Our results indicate that the cytoplasmic species contain conformational epitopes that may arise from yet undefined homo or hetero-oligomers, but its localization otherwise agrees with that of the other group of major E6 targets, those involving PDZ binding domains, which requires further investigation.