The use of directed evolution to create a stable and immunogenic recombinant BCG expressing a modified HIV-1 Gag antigen

Numerous features make Mycobacterium bovis BCG an attractive vaccine vector for HIV. It has a good safety profile, it elicits long-lasting cellular immune responses and in addition manufacturing costs are affordable. Despite these advantages it is often difficult to express viral antigens in BCG, which results in genetic instability and low immunogenicity. The aim of this study was to generate stable recombinant BCG (rBCG) that express high levels of HIV antigens, by modification of the HIV genes. A directed evolution process was applied to recombinant mycobacteria that expressed HIV-1 Gag fused to the green fluorescent protein (GFP). Higher growth rates and increased GFP expression were selected for. Through this process a modified Gag antigen was selected. Recombinant BCG that expressed the modified Gag (BCG[pWB106] and BCG[pWB206]) were more stable, produced higher levels of antigen and grew faster than those that expressed the unmodified Gag (BCG[pWB105]). The recombinant BCG that expressed the modified HIV-1 Gag induced 2 to 3 fold higher levels of Gag-specific CD4 T cells than those expressing the unmodified Gag (BCG[pWB105]). Mice primed with 10 7 CFU BCG[pWB206] and then boosted with MVA-Gag developed Gag-specific CD8 T cells with a frequency of 1343±17 SFU/10 6 splenocytes, 16 fold greater than the response induced with MVA-Gag alone. Levels of Gag-specific CD4 T cells were approximately 5 fold higher in mice primed with BCG[pWB206] and boosted with MVA-Gag than in those receiving the MVA-Gag boost alone. In addition mice vaccinated with BCG[pWB206] were protected from a surrogate vaccinia virus challenge

Meconium Aspiration Syndrome

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La tormenta perfecta: crisis e impeachment en el segundo mandato de Dilma Rousseff

Este artículo se propone analizar la emergencia de las distintas crisis −económica, política y social− y el modo en que las mismas se fueron amalgamando, conduciendo al impeachment durante el segundo mandato de la presidenta Dilma Rousseff (2014-2016). Con la confluencia de estas crisis en una “tormenta perfecta”, se terminaría desarmando el pacto social lulista que había garantizado la gobernabilidad de la coalición liderada por el Partido de los Trabajadores (PT) en estos años. Para ello, se realiza una breve reconstrucción del itinerario de los cuatro gobiernos del PT en Brasil. En tanto el éxito del impeachment concluye con un ciclo de trece años de gobiernos petistas en el poder, consideramos apropiado elaborar un balance provisorio acerca de los límites y las posibilidades que habilitaron este proceso político. El trabajo, si bien no cuenta con perspectiva histórica ni análisis sistemático, puede brindar unas primeras explicaciones para los acontecimientos de relevancia que se produjeron en el país de mayor gravitación geopolítica de Sudamérica