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Ramírez Álvarez, Hugo

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https://academica-e.unavarra.es/handle/2454/49818

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Ramírez Álvarez

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Hugo

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Instituto de Agrobiotecnología (IdAB)

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0000-0003-1682-8104

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6776

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2011 - 20133
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Now showing 1 - 3 of 3
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    PublicationOpen Access
    Small ruminant lentiviruses: genetic variability, tropism and diagnosis
    (MDPI, 2013) Ramírez Álvarez, Hugo; Reina Arias, Ramsés; Amorena Zabalza, Beatriz; Andrés Cara, Damián de; Martínez, Humberto A.; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
    Small ruminant lentiviruses (SRLV) cause a multisystemic chronic disease affecting animal production and welfare. SRLV infections are spread across the world with the exception of Iceland. Success in controlling SRLV spread depends largely on the use of appropriate diagnostic tools, but the existence of a high genetic/antigenic variability among these viruses, the fluctuant levels of antibody against them and the low viral loads found in infected individuals hamper the diagnostic efficacy. SRLV have a marked in vivo tropism towards the monocyte/macrophage lineage and attempts have been made to identify the genome regions involved in tropism, with two main candidates, the LTR and env gene, since LTR contains primer binding sites for viral replication and the env-encoded protein (SU ENV), which mediates the binding of the virus to the host’s cell and has hypervariable regions to escape the humoral immune response. Once inside the host cell, innate immunity may interfere with SRLV replication, but the virus develops counteraction mechanisms to escape, multiply and survive, creating a quasi-species and undergoing compartmentalization events. So far, the mechanisms of organ tropism involved in the development of different disease forms (neurological, arthritic, pulmonary and mammary) are unknown, but different alternatives are proposed. This is an overview of the current state of knowledge on SRLV genetic variability and its implications in tropism as well as in the development of alternative diagnostic assays.
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    PublicationOpen Access
    Identification of the ovine mannose receptor and its possible role in Visna/Maedi virus infection
    (BioMed Central, 2011) Crespo Otano, Helena; Reina Arias, Ramsés; Glaría Ezquer, Idoia; Ramírez Álvarez, Hugo; Andrés, Ximena de; Jauregui, Paula; Luján, Lluís; Martínez Pomares, Luisa; Amorena Zabalza, Beatriz; Andrés Cara, Damián de; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
    This study aims to characterize the mannose receptor (MR) gene in sheep and its role in ovine visna/maedi virus (VMV) infection. The deduced amino acid sequence of ovine MR was compatible with a transmembrane protein having a cysteine-rich ricin-type amino-terminal region, a fibronectin type II repeat, eight tandem C-type lectin carbohydrate-recognition domains (CRD), a transmembrane region, and a cytoplasmic carboxy-terminal tail. The ovine and bovine MR sequences were closer to each other compared to human or swine MR. Concanavalin A (ConA) inhibited VMV productive infection, which was restored by mannan totally in ovine skin fibroblasts (OSF) and partially in blood monocyte-derived macrophages (BMDM), suggesting the involvement of mannosylated residues of the VMV ENV protein in the process. ConA impaired also syncytium formation in OSF transfected with an ENV-encoding pN3-plasmid. MR transcripts were found in two common SRLV targets, BMDM and synovial membrane (GSM) cells, but not in OSF. Viral infection of BMDM and especially GSM cells was inhibited by mannan, strongly suggesting that in these cells the MR is an important route of infection involving VMV Env mannosylated residues. Thus, at least three patterns of viral entry into SRLV-target cells can be proposed, involving mainly MR in GSM cells (target in SRLV-induced arthritis), MR in addition to an alternative route in BMDM (target in SRLV infections), and an alternative route excluding MR in OSF (target in cell culture). Different routes of SRLV infection may thus coexist related to the involvement of MR differential expression.
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    PublicationOpen Access
    Study of compartmentalization in the visna clinical form of small ruminant lentivirus infection in sheep
    (BioMed Central, 2012) Ramírez Álvarez, Hugo; Reina Arias, Ramsés; Bertolotti, Luigi; Cenoz García, Amaia; Hernández, Mirna Margarita; San Román Aberasturi, Beatriz; Glaría Ezquer, Idoia; Andrés, Ximena de; Crespo Otano, Helena; Jauregui, Paula; Benavides, Julio; Polledo, Laura; Pérez, Valentín; García Marín, Juan F.; Rosati, Sergio; Amorena Zabalza, Beatriz; Andrés Cara, Damián de; IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua; Gobierno de Navarra / Nafarroako Gobernua: IIQ010449.RI1; Gobierno de Navarra / Nafarroako Gobernua: IIQ14064.RI1; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    Background: A central nervous system (CNS) disease outbreak caused by small ruminant lentiviruses (SRLV) has triggered interest in Spain due to the rapid onset of clinical signs and relevant production losses. In a previous study on this outbreak, the role of LTR in tropism was unclear and env encoded sequences, likely involved in tropism, were not investigated. This study aimed to analyze heterogeneity of SRLV Env regions - TM amino terminal and SU V4, C4 and V5 segments - in order to assess virus compartmentalization in CNS. Results: Eight Visna (neurologically) affected sheep of the outbreak were used. Of the 350 clones obtained after PCR amplification, 142 corresponded to CNS samples (spinal cord and choroid plexus) and the remaining to mammary gland, blood cells, bronchoalveolar lavage cells and/or lung. The diversity of the env sequences from CNS was 11.1-16.1% between animals and 0.35-11.6% within each animal, except in one animal presenting two sequence types (30% diversity) in the CNS (one grouping with those of the outbreak), indicative of CNS virus sequence heterogeneity. Outbreak sequences were of genotype A, clustering per animal and compartmentalizing in the animal tissues. No CNS specific signature patterns were found. Conclusions: Bayesian approach inferences suggested that proviruses from broncoalveolar lavage cells and peripheral blood mononuclear cells represented the common ancestors (infecting viruses) in the animal and that neuroinvasion in the outbreak involved microevolution after initial infection with an A-type strain. This study demonstrates virus compartmentalization in the CNS and other body tissues in sheep presenting the neurological form of SRLV infection.