CD8+ cytolytic T cell clones derived against the Plasmodium yoelii circumsporozoite protein protect against malaria

Immunization of BALB/c mice with radiation-attenuated Plasmodium yoelli sporozoites induces cytotoxic T lymphocytes (CTL) specific for an epitope located within the amlno acid sequence 277-288 of the P. yoellicircumsporozoite (CS) protein. Several CD8 + CTL clones were derived from the spleen cells of sporozolte-immunlzed mice, all displaying an apparently identical epitope specificity. All the clones Induced high levels of cytotysls in vitro upon exposure to peptide-incubated MHC-compatlble target cells. The adoptive transfer of two of these clones conferred complete protection against sporozotte challenge to naive mice. This protection Is species and stage specific. Using P. yoelli specific ribosomal RNA probes to monitor the in vivo effects of the CTL clones, we found that their target was the intrahepatocytic stage of the parasite. The protective clones completely Inhibited the development of the liver stages of P. yoelli Some CTL clones were only partially Inhibitory in vivo, while others failed completely to alter liver stage development and to confer any detectable degree of protection. The elucidation of the effector mechanism of this CTL mediated protection against rodent malaria should facilitate the design of an effective malaria vaccine. From a broader perspective this model may provide further insight into the mechanlsm(s) of CTL mediated killing of intracellular non-viral pathogens in genera

MEP-2 programa de computador para manejo de praderas con bovinos en el trópico Colombiano I - desarrollo informático.

sumarios (En, Es)Se diseñó y desarrolló una herramienta informática (Manejo Experto de Praderas: MEP-2®) para simular el comportamiento de las gramíneas tropicales frente al pastoreo con bovinos y para establecer los períodos de uso y recuperación de las praderas, en función de la producción de biomasa comestible, su calidad y consumo por parte de los animales. Así mismo, MEP-2® incorpora variables de calidad del forraje y de distensión del rumen, de acuerdo con un modelo de simulación de consumo de materia seca (MS) simple y de fácil implementación. El sistema fue estructurado previamente en hoja de cálculo y posteriormente trasladado a Visual Basic 6T, la información de identificación de la finca, tipo de ganado, especies de pastos y sistema de pastoreo se almacenó en formato AccessT. El programa consta de seis ventanas que se abren secuencialmente una vez se diligencia la información solicitada: dos ventanas corresponden a la evaluación de la disponibilidad de forraje según el tipo de gramínea: erecta o postrada. Otras dos ventanas registran información de la finca y las praderas con sus características individuales. De las dos ventanas finales, una corresponde a los resultados de la simulación y la otra a su interpretación, además de algunas recomendaciones generales. El propósito de la herramienta es proporcionar a ganaderos y asistentes técnicos un sistema objetivo para la toma de decisiones en el manejo de las praderas contribuyendo de esta manera a su sostenibilidad y a una mayor eficiencia de los animales.Ganadería bovin

MEP-2 programa de computador para manejo de praderas con bovinos en el trópico Colombiano. II - evaluación en el campo del programa.

"sumarios (En, Es)Se evaluó un programa de computador diseñado para predecir la utilización de praderas con bovinos bajo diferentes sistemas de pastoreo en distintos escenarios y regiones de Colombia y se compararon las predicciones de disponibilidad de biomasa, tiempos de pastoreo y de recuperación contra los datos observados en cada una de las fincas. Se incluyeron una finca en el Valle del Cesar con vacas doble propósito secas bajo pastoreo rotacional en praderas de pasto Guinea, una finca en el Piedemonte del Meta con novillos de ceba bajo pastoreo alterno de Brachiaria decumbens, una finca en el Magdalena Medio santandereano con novillos de ceba en pastoreo rotacional de Brachiaria humidícola y una finca en la Sabana de Bogotá con vacas de ordeño bajo pastoreo de Kikuyo-Ryegrass en franjas de un día. En cada una de las fincas se evaluaron dos rotaciones completas en cada época climática (sequía, lluvias). El análisis de las predicciones contra las observaciones en las variables días de ocupación, descanso y disponibilidad de forraje, se realizó mediante una comparación de medias con prueba de ""t"" (a de 5 por ciento). El consumo animal de MS predicho por el programa se analizó en relación con variables de calidad del forraje: proteína cruda, digestibilidad y Fibra en Detergente Neutro, mediante regresión lineal simple, encontrándose una correlación media para las tres variables con el consumo. Se concluye que el programa de simulación ayuda a la toma de decisiones sobre manejo de praderas, con mayor precisión durante la época de lluvias, mientras que para la época seca, los resultados deben tomarse con precaución realizando una evaluación o aforo de las praderas cuidadosa."Ganado de leche-Ganadería lech

CD8+ cytolytic T cell clones derived against the Plasmodium yoelii circumsporozoite protein protect against malaria

Immunization of BALB/c mice with radiation-attenuated Plasmodium yoelii sporozoites induces cytotoxic T lymphocytes (CTL) specific for an epitope located within the amino acid sequence 277-288 of the P. yoelii circumsporozoite (CS) protein. Several CD8+ CTL clones were derived from the spleen cells of sporozoite-immunized mice, all displaying an apparently identical epitope specificity. All the clones induced high levels of cytolysis in vitro upon exposure to peptide-incubated MHC-compatible target cells. The adoptive transfer of two of these clones conferred complete protection against sporozoite challenge to naive mice. This protection is species and stage specific. Using P. yoelii specific ribosomal RNA probes to monitor the in vivo effects of the CTL clones, we found that their target was the intrahepatocytic stage of the parasite. The protective clones completely inhibited the development of the liver stages of P. yoelii. Some CTL clones were only partially inhibitory in vivo, while others failed completely to alter liver stage development and to confer any detectable degree of protection. The elucidation of the effector mechanism of this CTL mediated protection against rodent malaria should facilitate the design of an effective malaria vaccine. From a broader perspective this model may provide further insight into the mechanism(s) of CTL mediated killing of intracellular non-viral pathogens in general

Protein moonlighting in parasitic protists

Reductive evolution during the adaptation to obligate parasitism and expansions of gene families encoding virulence factors are characteristics evident to greater or lesser degrees in all parasitic protists studied to date. Large evolutionary distances separate many parasitic protists from the yeast and animal models upon which classic views of eukaryotic biochemistry are often based. Thus a combination of evolutionary divergence, niche adaptation and reductive evolution means the biochemistry of parasitic protists is often very different from their hosts and to other eukaryotes generally, making parasites intriguing subjects for those interested in the phenomenon of moonlighting proteins. In common with other organisms, the contribution of protein moonlighting to parasite biology is only just emerging, and it is not without controversy. Here, an overview of recently identified moonlighting proteins in parasitic protists is provided, together with discussion of some of the controversies

Effector and Naturally Occurring Regulatory T Cells Display No Abnormalities in Activation Induced Cell Death in NOD Mice

BACKGROUND: Disturbed peripheral negative regulation might contribute to evolution of autoimmune insulitis in type 1 diabetes. This study evaluates the sensitivity of naïve/effector (Teff) and regulatory T cells (Treg) to activation-induced cell death mediated by Fas cross-linking in NOD and wild-type mice. PRINCIPAL FINDINGS: Both effector (CD25(-), FoxP3(-)) and suppressor (CD25(+), FoxP3(+)) CD4(+) T cells are negatively regulated by Fas cross-linking in mixed splenocyte populations of NOD, wild type mice and FoxP3-GFP trangeneess. Proliferation rates and sensitivity to Fas cross-linking are dissociated in Treg cells: fast cycling induced by IL-2 and CD3/CD28 stimulation improve Treg resistance to Fas-ligand (FasL) in both strains. The effector and suppressor CD4(+) subsets display balanced sensitivity to negative regulation under baseline conditions, IL-2 and CD3/CD28 stimulation, indicating that stimulation does not perturb immune homeostasis in NOD mice. Effective autocrine apoptosis of diabetogenic cells was evident from delayed onset and reduced incidence of adoptive disease transfer into NOD.SCID by CD4(+)CD25(-) T cells decorated with FasL protein. Treg resistant to Fas-mediated apoptosis retain suppressive activity in vitro. The only detectable differential response was reduced Teff proliferation and upregulation of CD25 following CD3-activation in NOD mice. CONCLUSION: These data document negative regulation of effector and suppressor cells by Fas cross-linking and dissociation between sensitivity to apoptosis and proliferation in stimulated Treg. There is no evidence that perturbed AICD in NOD mice initiates or promotes autoimmune insulitis