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Gomez F.A.,Pontifical Catholic University of Valparaiso | Tobar J.A.,Laboratorio Centrovet | Henriquez V.,Pontifical Catholic University of Valparaiso | Sola M.,Laboratorio Centrovet | And 3 more authors.
PLoS ONE | Year: 2013

Piscirickettsia salmonis is a fish bacterial pathogen that has severely challenged the sustainability of the Chilean salmon industry since its appearance in 1989. As this Gram-negative bacterium has been poorly characterized, relevant aspects of its life cycle, virulence and pathogenesis must be identified in order to properly design prophylactic procedures. This report provides evidence of the functional presence in P. salmonis of four genes homologous to those described for Dot/Icm Type IV Secretion Systems. The Dot/Icm System, the major virulence mechanism of phylogenetically related pathogens Legionella pneumophila and Coxiella burnetii, is responsible for their intracellular survival and multiplication, conditions that may also apply to P. salmonis. Our results demonstrate that the four P. salmonis dot/icm homologues (dotB, dotA, icmK and icmE) are expressed both during in vitro tissue culture cells infection and growing in cell-free media, suggestive of their putative constitutive expression. Additionally, as it happens in other referential bacterial systems, temporal acidification of cell-free media results in over expression of all four P. salmonis genes, a well-known strategy by which SSTIV-containing bacteria inhibit phagosome-lysosome fusion to survive. These findings are very important to understand the virulence mechanisms of P. salmonis in order to design new prophylactic alternatives to control the disease. © 2013 Gómez et al. Source

Arancibia S.,Investigacion y Desarrollo | Arancibia S.,Laboratorio Centrovet | Barrientos A.,Laboratorio Centrovet | Torrejon J.,Laboratorio Centrovet | And 2 more authors.
Nanomedicine | Year: 2016

Aim: In the present study, we examine the effects of copper oxide nanoparticles (CuNP) on macrophage immune response and the signaling pathways involved. Materials & Methods: A peritonitis model was used to determine in vivo immune cells recruitment, while primary macrophages were used as an in vitro model for the cellular and molecular analysis. Results: In vivo, CuNP induce significant macrophages recruitment to the site of injection. In vitro, in LPS-stimulated primary macrophages, the co-treatment with CuNP inhibited the production of NO in a dose-dependent manner. The mechanism underlying NO and proinflammatory cytokines inhibition was associated with an increased arginase activity. Macrophage stimulation with CuNP did not provoke any cytokine secretion; however, arginase inhibition promoted TNFα and MIP-1β production. In addition, CuNP induced the expression of COX-2 and the production of PGE2 through arginase activation. Conclusion: Our results demonstrate that CuNP activate arginase and suppress macrophage innate immune response. © 2015 Sergio Arancibia. Source

Tobar J.A.,Laboratorio Centrovet | Jerez S.,Laboratorio Centrovet | Caruffo M.,Laboratorio Centrovet | Bravo C.,Laboratorio Centrovet | And 3 more authors.
Vaccine | Year: 2011

Effective oral immunization systems may be very helpful to the salmon industry, particularly during the seawater growth stages in which vaccination through injection is not possible. During the seawater growing stage, fish become more susceptible to several types of disease, due to the natural decay of vaccine-induced immune responses. In this study, we demonstrate the immune response and efficacy of a new salmonid rickettsial septicaemia (SRS) oral vaccine, developed using MicroMatrix™ Technology. The vaccine, which is administered together with daily feed ration, induces a specific immune response at local and systemic levels. Anti-Piscirickettsia salmonis specific antibodies were detected as soon as 300 degree-days after vaccination. Furthermore, oral vaccination was able to protect fish against a lethal pathogen challenge when administered either as a primary vaccination or as a booster for an injected vaccine. Results show that oral vaccination is an efficacious treatment for the prevention of SRS outbreaks throughout the salmon culture period. © 2010 Elsevier Ltd. Source

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