Glioma-Parvovirus Interactions: Molecular Insights and Therapeutic Potential

This work was supported by grants from the Spanish Ministerio de Ciencia e Innovación (SAF2008-03238) and Comunidad de Madrid (S-SAL/0185/2006) to the laboratory of J.M.A.The Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM) is in part supported by an institutional grant from Fundación Ramón Areces.Peer reviewe

Viral oncolysis that targets raf-1 signaling control of nuclear transport

The central role of Raf protein kinase isoforms in human cancer demands specific anti-Raf therapeutic inhibitors. Parvoviruses are currently used in experimental cancer therapy due to their natural oncotropism and lytic life cycle. In searching for mechanisms underlying parvovirus oncolysis, we found that trimers of the major structural protein (VP) of the parvovirus minute virus of mice (MVM), which have to be imported into the nucleus for capsid assembly, undergo phosphorylation by the Raf-1 kinase. Purified Raf-1 phosphorylated the capsid subunits in vitro to the two-dimensional pattern found in natural MVM infections. VP trimers isolated from mammalian cells translocated into the nucleus of digitonin-permeabilized human cells. In contrast, VP trimers isolated from insect cells, which are devoid of Raf-1, were neither phosphorylated nor imported into the mammalian nucleus. However, the coexpression of a constitutively active Raf-1 kinase in insect cells restored VP trimer phosphorylation and nuclear transport competence. In MVM-infected normal and transformed cells, Raf-1 inhibition resulted in cytoplasmic retention of capsid proteins, preventing their nuclear assembly and progeny virus maturation. The level of Raf-1 activity in cancer cells was consistent with the extent of VP specific phosphorylation and with the permissiveness to MVM infection. Thus, Raf-1 control of nuclear translocation of MVM capsid assembly intermediates provides a novel target for viral oncolysis. MVM may reinforce specific therapies against frequent human cancers with deregulated Raf signaling. © 2010, American Society for Microbiology. All Rights Reserved.This study was supported by grants from the Spanish Ministerio de Ciencia e Innovación (SAF2008-03238) and Comunidad de Madrid (S-SAL/0185/2006) to the laboratory of J.M.A. and by an institutional grant from Fundación Ramón Areces to the Centro de Biología Molecular “Severo Ochoa.” L.R. was supported in part by a short-term EMBO fellowship.Peer Reviewe

Intracellular virion traffic to the endosome driven by cell type specific sialic acid receptors determines parvovirus tropism

Parvoviruses are promising anticancer and gene therapy agents, but a deep knowledge of the entry process is crucial to exploit their therapeutic potential. We addressed this issue while attempting to retarget the oncolytic parvovirus minute virus of mice (MVMp) to the tumor vasculature. Residues at three functional domains of the icosahedral capsid were substituted by rational design with peptides competing with the vascular endothelial growth factor. Most substitutions impaired virus maturation, though some yielded infectious chimeric virions, and substitutions in a dimple at the twofold axis that allocates sialic acid (SIA) receptors altered viral tropism. One dimple-modified chimeric virion was efficiently attached as MVMp to α2-linked SIA moieties, but the infection was impaired by the binding to some inhibitory α2-3,-6,-8 SIA pseudoreceptors, which hampers intracellular virus traffic to the endosome in a cell type-dependent manner. Infectious from nonproductive traffic could be mechanistically discriminated by an endosomal drastic capsid structural transition comprising the cleavage of some VP2-Nt sequences and its associated VP1-Nt exposure. Correspondingly, neuraminidase removal of inhibitory SIA moieties enhanced the infection quantitatively, correlating to the restored virus traffic to the endosome and the extent of VP2-Nt cleavage/VP1-Nt exposure. This study illustrates (i) structural constraints to retarget parvoviruses with evolutionary adopted narrow grooves allocating small SIA receptors, (ii) the possibility to enhance parvovirus oncolysis by relaxing the glycan network on the cancer cell surface, and (iii) the major role played by the attachment to cell type-specific SIAs in the intracellular virus traffic to the endosome, which may determine parvovirus tropism and host range

African swinw fever (ASF) virus: A missing link between poxviruses and iridoviruses

Trabajo presentado en el VII International Congress of Virology, celebrado en Edmonton (Canadá) del 09 al 14 de agosto de 1987

Care bundle for the prevention of peripheral venous catheter blood stream infections at a secondary care university hospital: implementation and results

Background: Venous catheterization for diagnostic and therapeutic purposes is part of routine hospital practice, as approximately 70% of hospitalized patients have a peripheral venous catheter (PVC). This practice, however, can lead to both local complications, (e.g., chemical, mechanical and infectious phlebitis) and systemic complications (e.g., PVC-related bloodstream infections [PVC-BSIs]). Surveillance data and activities are central to preventing nosocomial infections, phlebitis and improving patient care and safety. The aim of this study was to evaluate the impact of a care bundle on reducing PVC-BSI rates and phlebitis at a secondary care hospital in Mallorca, Spain. Methods: Three-phase intervention study targeting hospitalized patients with a PVC. The VINCat criteria were used to define PVC-BSIs and calculate incidence. In phase I (August-December 2015), we retrospectively analyzed baseline PVC-BSI rates at our hospital. In phase II (2016-2017), we conducted safety rounds and developed a care bundle with the goal of reducing PVC-BSI rates. In phase III (2018), we expanded the PVC-BSI bundle to prevent phlebitis and analyzed its impact. Results: The incidence of PVC-BSIs decreased from 0.48 episodes per 1000 patient-days in 2015 to 0.17 episodes per 1000 patient-days in 2018. The 2017 safety rounds also detected a reduction in phlebitis (from 4.6% of 2.6%). Overall, 680 healthcare professionals were trained in catheter care and five safety rounds were conducted to assess bedside care. Conclusion: Implementation of a care bundle significantly reduced PVC-BSI rates and phlebitis at our hospital. Continuous surveillance programs are needed to adapt measures to improve patient care and guarantee safety

Bioprospecting reveals class III ω-transaminases converting bulky ketones and environmentally relevant polyamines

Amination of bulky ketones, particularly in (R) configuration, is an attractive chemical conversion; however, known ω-transaminases (ω-TAs) show insufficient levels of performance. By applying two screening methods, we discovered 10 amine transaminases from the class III ω-TA family that were 38% to 76% identical to homologues. We present examples of such enzymes preferring bulky ketones over keto acids and aldehydes with stringent (S) selectivity. We also report representatives from the class III ω-TAs capable of converting (R) and (S) amines and bulky ketones and one that can convert amines with longer alkyl substituents. The preference for bulky ketones was associated with the presence of a hairpin region proximal to the conserved Arg414 and residues conforming and close to it. The outward orientation of Arg414 additionally favored the conversion of (R) amines. This configuration was also found to favor the utilization of putrescine as an amine donor, so that class III ω-TAs with Arg414 in outward orientation may participate in vivo in the catabolism of putrescine. The positioning of the conserved Ser231 also contributes to the preference for amines with longer alkyl substituents. Optimal temperatures for activity ranged from 45 to 65°C, and a few enzymes retained ≥50% of their activity in water-soluble solvents (up to 50% [vol/vol]). Hence, our results will pave the way to design, in the future, new class III ω-TAs converting bulky ketones and (R) amines for the production of high-value products and to screen for those converting putrescine

Assembly of simple icosahedral viruses

Icosahedral viruses exhibit elegant pathways of capsid assembly and maturation regulated by symmetry principles. Assembly is a dynamic process driven by consecutive and genetically programmed morphogenetic interactions between protein subunits. The non-symmetric capsid subunits are gathered by hydrophobic contacts and non-covalent interactions in assembly intermediates, which serve as blocks to build a symmetric capsid. In some cases, non-symmetric interactions among intermediates are involved in assembly, highlighting the remarkable capacity of capsid proteins to fold into demanding conformations compatible with a closed protein shell. In this chapter, the morphogenesis of structurally simple icosahedral viruses, including representative members of the parvoviruses, picornaviruses or polyomaviruses as paradigms, is described in some detail. Icosahedral virus assembly may occur in different subcellular compartments and involve a panoplia of cellular and viral factors, chaperones, and protein modifications that, in general, are still poorly characterized. Mechanisms of viral genome encapsidation may imply direct interactions between the genome and the assembly intermediates, or active packaging into a preformed empty capsid. High stability of intermediates and proteolytic cleavages during viral maturation usually contribute to the overall irreversible character of the assembly process. These and other simple icosahedral viruses were pioneer models to understand basic principles of virus assembly, continue to be leading subjects of morphogenetic analyses, and have inspired ongoing studies on the assembly of larger viruses and cellular and synthetic macromolecular complexes.Spanish Ministerio de Ciencia e Innovación (SAF 2011-29403)Peer Reviewe

Producción, valoración y diagnóstico de virus

23 páginas, 17 figuras.Los avances en el diagnóstico y valoración de los virus patógenos se han ido produciendo en paralelo con el refinamiento de las técnicas de cultivo de células eucariotas y de los ensayos para la detección de macromoléculas biológicas, cuya sensibilidad y especificidad ha experimentado un incremento muy importante en la última década. En este capítulo se revisan las técnicas y los requerimientos para el cultivo de células eucariotas, los métodos para la producción y purificación de preparaciones virales libres de contaminantes celulares, y los ensayos que posibilitan la detección y diagnóstico de las enfermedades producidas por la infección viral. Por razones de espacio esta revisión no puede ser muy exhaustiva, pero se abarcan en ella con cierta profundidad los diversos aspectos relacionados con la producción viral.Fundación BBVA.Peer reviewe

Parvovirus minute virus of mice strain i multiplication and pathogenesis in the newborn mouse brain are restricted to proliferative areas and to migratory cerebellar young neurons

Newborn BALB/c mice intranasally inoculated at birth with a lethal dose of the immunosuppressive strain of the parvovirus minute virus of mice (MVMi) developed motor disabilities and intention tremors with a high incidence by the day 6 postinfection (dpi). These neurological syndromes paralleled the synthesis of virus intermediate DNA replicative forms and yield of infectious particles in the brain, with kinetics that peaked by this time. The preferred virus replicative sites in the brain were established early in the infection (2 dpi) and at the onset of clinical symptoms (6 dpi) and were compared with major regions of cellular proliferative activity found after intraperitoneal injection of bromodeoxyuridine 24 h before encephalons were subjected to immunohistochemistry detection. At 2 dpi, viral capsid antigen was located in the laterodorsal thalamic and the pontine nuclei but not in the extensive proliferative regions of the mouse brain at this postnatal day. At 6 dpi, however, the neurotropism of the MVMi was highlighted by its ability to target the subventricular zone of the ventricles, the subependymal zone of the olfactory bulb, and the dentate gyrus of the hippocampus, which are the three main germinal centers of the cerebrum in mouse postbirth neurogenesis. Unexpectedly, in the cerebellum, the MVMi capsid antigen was confined exclusively to cells that have undergone mitosis and have migrated to the internal granular layer (IGL) and not to the proliferative external granular layer (EGL), which was stained with antiproliferative cell nuclear antigen antibody and is the main target in other parvovirus infections. This result implies temporal or differentiation coupling between MVMi cycle and neuroblast morphogenesis, since proliferative granules of the EGL should primarily be infected but must migrate in a virus carrier state into the IGL in order to express the capsid proteins. During migration, many cells undergo destruction, accounting for the marked hypocellularity specifically found in the IGL and the irregular alignment of Purkinje cell bodies, both consistent histopathological hallmarks of animals developing cerebellar symptoms. We conclude that MVMi impairs postmitotic neuronal migration occurring in the first postnatal week, when, through the natural respiratory route of infection, the virus titer peaks in the encephalon. The results illustrate the intimate connection between MVMi neuropathogenesis and mouse brain morphogenetic stage, underscoring the potential of parvoviruses as markers of host developmental programs.Peer Reviewe