Este trabajo fue financiado por el subsidio PRB-009 para CS y una beca doctoral a LC, de la Secretaría Nacional de Ciencia y Tecnología (SENACYT) de Panamá, Panamá.

Todas las etapas del protocolo, a excepción de centrifugaciones, debe llevarse a cabo dentro de una campana para mantener la muestra estéril. 1. Aislamiento en estadio tardío de P. falciparum-eritrocitos infectados Todas las etapas tardías de Plasmodium eritrocitos infectados se pueden separar con esta metodología, ya hemozoína que confiere el paramagnetismo en el parásito, es un metabolito común al género. Una alta parasitemia (3-10%) en cultivo se recomienda para obtener mejores rendimientos con este protocolo, aunque una cultura típica contiene 2-4% de hematocrito (porcentaje en volumen de células rojas de la sangre) y 1-8% de parasitemia (porcentaje de infectados las células rojas de la sangre). Los parásitos pueden ser cultivados como se describe por Trager y Jansen 1. <ol><li> A simple, multi-parte de configuración debe estar montado para cada procedimiento de aislamiento de esquizontes. Para ello, las columnas LS, un separador magnético y un midiMACS MultiStand MACS de Miltenyi Biotec (Figura 1 </strong&gt;) se utilizan. En primer lugar, coloque el separador magnético para el soporte de metal y luego coloque la columna magnética en el separador. </li><li> En un tubo separado (utilizar 50 ml cónicos largo), mezclar 23,2 ml de RPMI 1640 y 750 l de bicarbonato sódico al 7,5% para crear la solución de trabajo. Tienen tubos adicionales en la mano para recoger y desechar el flujo a través de la cultura parásito. </li><li> Añadir 3 ml de la solución de trabajo a la columna para que se equilibren, y desechar el flujo a través de un tubo. </li><li> Añadir 8 ml de la P. falciparum cultura a la columna, asegurándose de que tan pronto como la última parte de la solución de trabajo ha sido empujado fuera de la columna por la cultura, el tubo receptor se sustituye por el de recogida para comenzar la recuperación de la cultura no unido. Esto es necesario para evitar diluir el cultivo más allá. </li><li> Una vez que el flujo de la cultura a través de la columna ha cesado, añadir 1 ml de la solución de trabajo para empujar los glóbulos rojos que quedan fuera de la columna. </li><li> Etapa de lavado: Añadir otra ml 3 de la solución de trabajo a la columna y recoger el líquido que fluye en el &quot;descarte&quot; tubo a fin de evitar la dilución de la cultura que se guarda como de flujo a través en el otro tubo. </li><li> La elución: Una vez que el 3 ml han pasado a través de la columna, separar este último del soporte y colocarlo en la parte superior de un tubo de 15 ml. </li><li> Una vez más, añadir 3 ml de solución de trabajo a la columna. Este paso se eluye de los eritrocitos infectados con parásitos de etapa tardía que quedaron atrapados en las cuentas de la columna. </li></ol> Nota: En este punto, y en función de la cantidad de parásitos necesario, iniciar otra ronda / s de recogida, obviamente, sujeto a los límites de la parasitemia en el cultivo original. La columna se puede reutilizar siempre y cuando el flujo mantiene un estado estacionario. <ol start="9"><li> La concentración de los parásitos recogidos: Se centrifuga el tubo de 15 ml que contiene el eluido durante 5 minutos a 150 xg, a temperatura ambientepara formar un sedimento oscuro de los eritrocitos parasitados. </li><li> Eliminar el sobrenadante dejando suficiente líquido para tomar una pequeña muestra y determinar la concentración y el rendimiento total a través de microscopía (Ver paso 2). </li><li> En este momento, si el aislamiento y la captura de los parásitos en fase tardía se realiza satisfactoriamente, incubar el cultivo recogido de nuevo con medio fresco. </li><li> Diluir los parásitos recogidos en el volumen y la solución necesaria para los experimentos posteriores. </li></ol> 2. Pureza y Análisis de Rendimiento <ol><li> Comprobar la concentración de parásitos obtenidos mediante el uso de un hemocitómetro y recuento bajo un microscopio de luz. Para contar, añadir 10 l de la mezcla de los parásitos recogidos y medios de comunicación bajo el cubreobjetos del hemocitómetro. Contar el número de parásitos en los cuatro cuadrantes del hemocitómetro y se dividen por el número total 4. Multiplicar este número por 10 4 para obtener la concentración de e infectadarythrocytes por ml. </li></ol> Notas: a) La concentración de la mezcla será decidido por el usuario en el momento de la resuspensión del sedimento, mediante la adición de más o menos medio. Una concentración de trabajo que se sugiere es de 5,5 x 10 4 schizontes por microlitro (esto normalmente se logra mediante la adición de 100-300 l de los parásitos recogidos). Si 20 l de esta concentración se añade a un volumen final de 100 l de mezcla de medios de comunicación y eritrocitos, una parasitemia de aproximadamente 1% en un cultivo típico hematocrito 4% se obtendrá. b) Contar en el hemocitómetro tiene que ser rápido, ya que los eritrocitos iniciar lisis como se seca la muestra dentro de la cámara. Eritrocitos infectados, que deben ser la mayoría, se mostrará una mancha oscura en el interior, lo que los diferencia de los no infectados. <ol start="2"><li> Realizar una Giemsa en capa fina tinción para evaluar la pureza de la recogida mediante la fijación de las diapositivas muy rápidamente en 10% de metanol, secado, y sumergiendo tdobladillo en una solución de 20% de tinción de Giemsa diluido con agua destilada. Teñir los portaobjetos durante 10 min, después de lo cual se puede secar por aire y se examina bajo el microscopio. Un parasitemia muy por encima de 70% deben ser alcanzables. </li></ol>

<ol>
	<li>Jensen, J. B., Trager, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmodium+falciparum+in+culture:+use+of+outdated+erythrocytes+and+description+of+the+candle+jar+method.">Plasmodium falciparum in culture: use of outdated erythrocytes and description of the candle jar method.</a> J. Parasitology. 63 (5), 883-886 (1977).</li><li>Guzman, I. Y., Francis, S. E., Oksman, A., Smith, C. E., Duffin, K. L., Goldberg, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Order+and+specificity+of+the+Plasmodium+falciparum+hemoglobin+degradation+pathway.">Order and specificity of the Plasmodium falciparum hemoglobin degradation pathway.</a> J. Clin. Invest. 93, 1602-1608 (1994).</li><li>Rosenthal, P. J., Meshnick, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemoglobin+catabolism+and+iron+utilization+by+malaria+parasites.">Hemoglobin catabolism and iron utilization by malaria parasites.</a> Mol. Biochem. Parasitol. 83 (2), 131-139 (1996).</li><li>Fitch, C. D., Chevli, R., Kanjananggulpan, P., Dutta, P., Chevli, K., Chou, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracellular+ferriprotoporphyrin+IX+is+a+lytic+agent.">Intracellular ferriprotoporphyrin IX is a lytic agent.</a> Blood. 62 (6), 1165-1168 (1983).</li><li>Hebbel, R. P., Eaton, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathobiology+of+heme+interaction+with+the+erythrocyte+membrane.">Pathobiology of heme interaction with the erythrocyte membrane.</a> Semin. Hematol. 26 (2), 136-149 (1989).</li><li>Egan, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Haemozoin+formation.">Haemozoin formation.</a> Mol. Biochem. Parasitol. 157 (2), 127-136 (2008).</li><li>Hempelmann, E., Marques, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+malaria+pigment+from+Plasmodium+falciparum.">Analysis of malaria pigment from Plasmodium falciparum.</a> J. Pharmacol. Toxicol. Methods. 32 (1), 25-30 (1994).</li><li>Fitch, C. D., Kanjananggulpan, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+state+of+ferriprotoporphyrin+IX+in+malaria+pigment.">The state of ferriprotoporphyrin IX in malaria pigment.</a> J. Biol. Chem. 262 (32), 15552-15555 (1987).</li><li>Moore, L. R., Fujioka, H., Williams, P. S., Chalmers, J. J., Grimberg, B., Zimmerman, P. A., Zborowski, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemoglobin+degradation+in+malaria-infected+erythrocytes+determined+from+live+cell+magnetophoresis.">Hemoglobin degradation in malaria-infected erythrocytes determined from live cell magnetophoresis.</a> FASEB J. 20 (6), 747-749 (2006).</li><li>Spadafora, C., Gerena, L., Kopydlowski, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+the+in+vitro+invasive+capabilities+of+Plasmodium+falciparum+schizonts+isolated+by+Percoll+gradient+or+using+magnetic+based+separation.">Comparison of the in vitro invasive capabilities of Plasmodium falciparum schizonts isolated by Percoll gradient or using magnetic based separation.</a> Malaria J. 10, 96 (2011).</li><li>Jackson, K. E., Spielmann, T., Hanssen, E., Adisa, A., Separovic, F., Dixon, M. W., Trenholme, K. R., Hawthorne, P. L., Gardiner, D. L., Gilberger, T., Tilley, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+permeabilization+of+the+host+cell+membrane+of+Plasmodium+falciparum-infected+red+blood+cells+with+streptolysin+O+and+equinatoxin+II.">Selective permeabilization of the host cell membrane of Plasmodium falciparum-infected red blood cells with streptolysin O and equinatoxin II.</a> Biochem. J. 403, 167-175 (2007).</li><li>Goodyer, I. D., Johnson, J., Eisenthal, R., Hayes, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+of+mature-stage+Plasmodium+falciparum+by+gelatine+flotation.">Purification of mature-stage Plasmodium falciparum by gelatine flotation.</a> Ann. Trop. Med. Parasitol. 88 (2), 209-211 (1994).</li><li>Pasvol, G., Wilson, R. J., Smalley, M. E., Brown, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Separation+of+viable+schizont-infected+red+cells+of+Plasmodium+falciparum+from+human+blood.">Separation of viable schizont-infected red cells of Plasmodium falciparum from human blood.</a> Ann. Trop. Med. Parasitol. 72, 87-88 (1978).</li><li>Pertoft, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fractionation+of+cells+and+subcellular+particles+with+Percoll.">Fractionation of cells and subcellular particles with Percoll.</a> J. Biochem. Biophys. Methods. 44 (1-2), 1-30 (2000).</li><li>Paul, F., Roath, S., Melville, D., Warhurst, D. C., Osisanya, J. O. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Separation+of+malaria-infected+erythrocytes+from+whole+blood:+use+of+a+selective+high-gradient+magnetic+separation+technique.">Separation of malaria-infected erythrocytes from whole blood: use of a selective high-gradient magnetic separation technique.</a> The Lancet. 318, 70-71 (1981).</li><li>Trang, D. T., Huy, N. T., Kariu, T., Tajima, K., Kamei, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One-step+concentration+of+malarial+parasite-infected+red+blood+cells+and+removal+of+contaminating+white+blood+cells.">One-step concentration of malarial parasite-infected red blood cells and removal of contaminating white blood cells.</a> Malar. J. 3, 7 (2004).</li><li>Nillni, E. A., Londner, M. V., Spira, D. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+method+for+separation+of+uninfected+erythrocytes+from+those+infected+with+Plasmodium+berghei+and+for+isolation+of+artificially+released+parasites.">A simple method for separation of uninfected erythrocytes from those infected with Plasmodium berghei and for isolation of artificially released parasites.</a> Z. Parasitenkd. 64, 279-284 (1981).</li></ol>

No tenemos nada que revelar.

Los cultivos in vitro del parásito de la malaria P. falciparum presentan una parasitemia limitada, con más de la mitad de las células rojas de la sangre infectadas en el punto más alto de la proliferación de cultivo. Para la mayoría de los experimentos de investigación, es deseable para trabajar sólo con los eritrocitos infectados. Con este fin, una técnica de separación es necesario dividir el cultivo de acuerdo a la infección. Los métodos útiles incluyen el uso de estreptolisina...

<table border="1"><tbody><tr><td> Nombre del reactivo </td><td> Empresa </td><td> Número de catálogo </td><td> Comentarios (opcional) </td></tr><tr><td> RPMI 1640 Hepes modificado </td><td> Sigma-Aldrich </td><td> R4130 </td><td> Suplementado con 10% de suero humano, 2% de glucosa, y 0,2% de bicarbonato de sodio </td></tr><tr><td> MidiMACS Separador </td><td> Miltenyi Biotec MACS </td><td> 130-042-302 </td><td></td></tr><tr><td> MACS MultiStand </td><td> Miltenyi Biotec MACS </td><td> 130-042-303 </td><td></td></tr><tr><td> Columnas LS </td><td> Miltenyi Biotec MACS </td><td> 130-042-401 </td><td></td></tr><tr><td> Hemocitómetro </td><td> Grafco </td><td> Grafco Cámara Neubauer </td><td> Se puede encontrar a través de muchos otros proveedores </td></tr></tbody></table>

separation of plasmodium falciparum late stage-infected erythrocytes by magnetic means

A diferencia de otras especies de Plasmodium, P. falciparum pueden ser cultivados en el laboratorio, lo que facilita su estudio 1. Mientras que la parasitemia alcanzado puede alcanzar el límite de ≈ 40%, el investigador normalmente impide que el porcentaje en torno al 10%. En muchos casos es necesario aislar las células rojas de parásito que contienen la sangre (glóbulos rojos) de los no infectados, para enriquecer la cultura y proceder con un experimento dado. Cuando P. falciparum infecta los eritrocitos, el parásito se degrada y se alimenta de hemoglobina 2, 3. Sin embargo, el parásito debe tratar con un resto hemo muy tóxico que contiene hierro 4, 5. El parásito elude su toxicidad mediante la transformación del hemo en un polímero de cristal inerte llamada haemozoin 6, 7. Esta molécula que contiene hierro se almacena en su vacuola alimentaria y el metal en él tiene un estado de oxidación que difiere de la de hemo 8. El estado férrico de hierro en el grupo hemoozoin le confiere una propiedad paramagnética ausente en los eritrocitos no infectados. Como el parásito invasor alcanza la madurez, el contenido de haemozoin 9 también aumenta, lo que confiere paramagnetismo aún más en las últimas etapas de P. falciparum en el interior de los eritrocitos. En base a esta propiedad paramagnética, las últimas etapas de la P. falciparum infectados células rojas de la sangre pueden ser separadas haciendo pasar la cultura a través de una columna que contiene perlas magnéticas. Estas perlas se vuelven magnéticos cuando las columnas contienen se coloca en un soporte de imán. Eritrocitos infectados, debido a su paramagnetismo, entonces quedará atrapado en el interior de la columna, mientras que el flujo a través contendrá, en su mayor parte, los eritrocitos no infectados y aquellos que contienen etapas tempranas del parásito. Aquí, se describe la metodología para enriquecer la población de parásitos en fase tardía con columnas magnéticas, lo que mantiene la viabilidad del parásito buena 10.Después de realizar este procedimiento, la cultura no unida puede ser devuelto a una incubadora para permitir que los parásitos restantes para continuar creciendo.

En la Figura 2, el cultivo pasa a través de la columna magnética se muestra, antes (A) y después del procedimiento (B). Una a dos eritrocitos infectados se ven generalmente en un campo de aumento de 100X, como se muestra en la Figura 2, con las flechas apuntando a los eritrocitos infectados en la Figura 2A. En un procedimiento típico, a partir de un cultivo a 5% de parasitemia (Figura 2A), el rendimiento de este pro...

Watch this Scientific Journal Video about Separation of Plasmodium falciparum Late Stage-infected Erythrocytes by Magnetic Means at JoVE.com

Separation of Plasmodium falciparum Late Stage-infected Erythrocytes by Magnetic Means

Las propiedades paramagnéticas de hemozoína se utilizan para aislar las últimas etapas de<em&gt; Plasmodium falciparum</em&gt;-Infectados glóbulos rojos que crecen en cultivo. El método es simple y rápido y no afecta a las capacidades invasivas posteriores de los parásitos.

Separación de los<em&gt; Plasmodium falciparum</em&gt; Late Stage-eritrocitos infectados por medios magnéticos

Unlike other Plasmodium species, P. falciparum can be cultured in the lab, which facilitates its study 1. While the parasitemia achieved can reach the ...

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Research

JoVE Journal

Immunology and Infection

Separation of Plasmodium falciparum Late Stage-infected Erythrocytes by Magnetic Means

13.8K vistas.  Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP). Las propiedades paramagnéticas de hemozoína se utilizan para aislar las últimas etapas de Plasmodium falciparum-Infectados glóbulos rojos que crecen en cultivo. El método es simple y rápido y no afecta a las capacidades invasivas posteriores de los parásitos.

Video: Separation of Plasmodium falciparum Late Stage-infected Erythrocytes by Magnetic Means

Ex vivo Expansion of Tumor-reactive T Cells by Means of Bryostatin 1/Ionomycin and the Common Gamma Chain Cytokines Formulation

It was reported that breast cancer patients have pre-existing immune responses against their tumors1,2. However, such immune responses fail to provide complete protection against the development or recurrence of breast cancer. To overcome this problem by increasing the frequency of tumor-reactive T cells, adoptive immunotherapy has been employed. A variety of protocols have been used for the expansion of tumor-specific T cells. These protocols, however, are restricted to the use of tumor antigens ex vivo for the activation of antigen-specific T cells. Very recently, common gamma chain cytokines such as IL-2, IL-7, IL-15, and IL-21 have been used alone or in combination for the enhancement of anti-tumor immune responses3. However, it is not clear what formulation would work best for the expansion of tumor-reactive T cells. Here we present a protocol for the selective activation and expansion of tumor-reactive T cells from the FVBN202 transgenic mouse model of HER-2/neu positive breast carcinoma for use in adoptive T cell therapy of breast cancer. The protocol includes activation of T cells with bryostatin-1/ionomycin (B/I) and IL-2 in the absence of tumor antigens for 16 hours. B/I activation mimics intracellular signals that result in T cell activation by increasing protein kinase C activity and intracellular calcium, respectively4. This protocol specifically activates tumor-specific T cells while killing irrelevant T cells. The B/I-activated T cells are cultured with IL-7 and IL-15 for 24 hours and then pulsed with IL-2. After 24 hours, T cells are washed, split, and cultured with IL-7 + IL-15 for additional 4 days. Tumor-specificity and anti-tumor efficacy of the ex vivo expanded T cells is determined.

Ex vivo Expansion of Tumor-reactive T Cells by Means of Bryostatin 1/Ionomycin and the Common Gamma Chain Cytokines Formulation

An efficient protocol for the ex vivo expansion of tumor-reactive T cells from tumor-draining lymph nodes or other secondary lymphoid tissues of tumor-bearing hosts is described. This protocol selectively expands tumor-specific T cells for use in adoptive immunotherapy of breast cancer.

Expansión ex vivo de células T tumor-reactiva por medio de la 1/Ionomycin briostatina y la formulación de la cadena gamma común de citoquinas

It was reported that breast cancer patients have pre-existing immune responses against their tumors1,2. However, such immune responses fail to provide ...

Investigación

Inmunología e Infección

Selection of Plasmodium falciparum Parasites for Cytoadhesion to Human Brain Endothelial Cells

Most human malaria deaths are caused by blood-stage Plasmodium falciparum parasites. Cerebral malaria, the most life-threatening complication of the disease, is characterised by an accumulation of Plasmodium falciparum infected red blood cells (iRBC) at pigmented trophozoite stage in the microvasculature of the brain2-4. This microvessel obstruction (sequestration) leads to acidosis, hypoxia and harmful inflammatory cytokines (reviewed in 5). Sequestration is also found in most microvascular tissues of the human body2, 3. The mechanism by which iRBC attach to the blood vessel walls is still poorly understood.
The immortalized Human Brain microvascular Endothelial Cell line (HBEC-5i) has been used as an in vitro model of the blood-brain barrier6. However, Plasmodium falciparum iRBC attach only poorly to HBEC-5i in vitro, unlike the dense sequestration that occurs in cerebral malaria cases. We therefore developed a panning assay to select (enrich) various P. falciparum strains for adhesion to HBEC-5i in order to obtain populations of high-binding parasites, more representative of what occurs in vivo.
A sample of a parasite culture (mixture of iRBC and uninfected RBC) at the pigmented trophozoite stage is washed and incubated on a layer of HBEC-5i grown on a Petri dish. After incubation, the dish is gently washed free from uRBC and unbound iRBC. Fresh uRBC are added to the few iRBC attached to HBEC-5i and incubated overnight. As schizont stage parasites burst, merozoites reinvade RBC and these ring stage parasites are harvested the following day. Parasites are cultured until enough material is obtained (typically 2 to 4 weeks) and a new round of selection can be performed. Depending on the P. falciparum strain, 4 to 7 rounds of selection are needed in order to get a population where most parasites bind to HBEC-5i. The binding phenotype is progressively lost after a few weeks, indicating a switch in variant surface antigen gene expression, thus regular selection on HBEC-5i is required to maintain the phenotype.
In summary, we developed a selection assay rendering P. falciparum parasites a more "cerebral malaria adhesive" phenotype. We were able to select 3 out of 4 P. falciparum strains on HBEC-5i. This assay has also successfully been used to select parasites for binding to human dermal and pulmonary endothelial cells. Importantly, this method can be used to select tissue-specific parasite populations in order to identify candidate parasite ligands for binding to brain endothelium. Moreover, this assay can be used to screen for putative anti-sequestration drugs7.

Selection of Plasmodium falciparum Parasites for Cytoadhesion to Human Brain Endothelial Cells

An in vitro model for cerebral malaria sequestration is described1. Plasmodium falciparum infected red blood cells are selected for binding to immortalized human brain microvascular endothelial cells. The selected parasites show a distinct phenotype. The selection process can be applied using various P. falciparum strains and endothelial cell lines.

Selección de Plasmodium falciparum Los parásitos de cytoadhesion a las células cerebrales endoteliales humanas

Most human malaria deaths are caused by blood-stage Plasmodium falciparum parasites. Cerebral malaria, the most life-threatening complication of the ...

An In vitro Co-infection Model to Study Plasmodium falciparum-HIV-1 Interactions in Human Primary Monocyte-derived Immune Cells

Plasmodium falciparum, the causative agent of the deadliest form of malaria, and human immunodeficiency virus type-1 (HIV-1) are among the most important health problems worldwide, being responsible for a total of 4 million deaths annually1. Due to their extensive overlap in developing regions, especially Sub-Saharan Africa, co-infections with malaria and HIV-1 are common, but the interplay between the two diseases is poorly understood. Epidemiological reports have suggested that malarial infection transiently enhances HIV-1 replication and increases HIV-1 viral load in co-infected individuals2,3. Because this viremia stays high for several weeks after treatment with antimalarials, this phenomenon could have an impact on disease progression and transmission.
The cellular immunological mechanisms behind these observations have been studied only scarcely. The few in vitro studies investigating the impact of malaria on HIV-1 have demonstrated that exposure to soluble malarial antigens can increase HIV-1 infection and reactivation in immune cells. However, these studies used whole cell extracts of P. falciparum schizont stage parasites and peripheral blood mononuclear cells (PBMC), making it hard to decipher which malarial component(s) was responsible for the observed effects and what the target host cells were4,5. Recent work has demonstrated that exposure of immature monocyte-derived dendritic cells to the malarial pigment hemozoin increased their ability to transfer HIV-1 to CD4+ T cells6,7, but that it decreased HIV-1 infection of macrophages8. To shed light on this complex process, a systematic analysis of the interactions between the malaria parasite and HIV-1 in different relevant human primary cell populations is critically needed.
Several techniques for investigating the impact of HIV-1 on the phagocytosis of micro-organisms and the effect of such pathogens on HIV-1 replication have been described. We here present a method to investigate the effects of P. falciparum-infected erythrocytes on the replication of HIV-1 in human primary monocyte-derived macrophages. The impact of parasite exposure on HIV-1 transcriptional/translational events is monitored by using single cycle pseudotyped viruses in which a luciferase reporter gene has replaced the Env gene while the effect on the quantity of virus released by the infected macrophages is determined by measuring the HIV-1 capsid protein p24 by ELISA in cell supernatants.

An In vitro Co-infection Model to Study Plasmodium falciparum-HIV-1 Interactions in Human Primary Monocyte-derived Immune Cells

We have developed an in vitro malaria-HIV-1 co-infection model to study the impact of Plasmodium falciparum on the HIV-1 replicative cycle in human primary monocyte-derived macrophages. This versatile system can easily be adapted to other primary cell types susceptible to HIV-1 infection.

Un<em&gt; In vitro</em&gt; Co-infección modelo para estudiar<em&gt; Plasmodium falciparum</em&gt;-VIH-1 en las interacciones humano primario de monocitos derivados de las células inmunitarias

Plasmodium falciparum, the causative agent  of the deadliest form of malaria, and human immunodeficiency virus type-1 (HIV-1) are among the most important ...

A Simple Protocol for Platelet-mediated Clumping of Plasmodium falciparum-infected Erythrocytes in a Resource Poor Setting

P. falciparum causes the majority of severe malarial infections. The pathophysiological mechanisms underlying cerebral malaria (CM) are not fully understood and several hypotheses have been put forward, including mechanical obstruction of microvessels by P. falciparum-parasitized red blood cells (pRBC). Indeed, during the intra-erythrocytic stage of its life cycle, P. falciparum has the unique ability to modify the surface of the infected erythrocyte by exporting surface antigens with varying adhesive properties onto the RBC membrane. This allows the sequestration of pRBC in multiple tissues and organs by adhesion to endothelial cells lining the microvasculature of post-capillary venules 1. By doing so, the mature forms of the parasite avoid splenic clearance of the deformed infected erythrocytes 2 and restrict their environment to a more favorable low oxygen pressure 3. As a consequence of this sequestration, it is only immature asexual parasites and gametocytes that can be detected in peripheral blood.
Cytoadherence and sequestration of mature pRBC to the numerous host receptors expressed on microvascular beds occurs in severe and uncomplicated disease. However, several lines of evidence suggest that only specific adhesive phenotypes are likely to be associated with severe pathological outcomes of malaria. One example of such specific host-parasite interactions has been demonstrated in vitro, where the ability of intercellular adhesion molecule-1 to support binding of pRBC with particular adhesive properties has been linked to development of cerebral malaria 4,5. The placenta has also been recognized as a site of preferential pRBC accumulation in malaria-infected pregnant women, with chondrotin sulphate A expressed on syncytiotrophoblasts that line the placental intervillous space as the main receptor 6. Rosetting of pRBC to uninfected erythrocytes via the complement receptor 1 (CD35)7,8 has also been associated with severe disease 9.
One of the most recently described P. falciparum cytoadherence phenotypes is the ability of the pRBC to form platelet-mediated clumps in vitro. The formation of such pRBC clumps requires CD36, a glycoprotein expressed on the surface of platelets. Another human receptor, gC1qR/HABP1/p32, expressed on diverse cell types including endothelial cells and platelets, has also been shown to facilitate pRBC adhesion on platelets to form clumps 10. Whether clumping occurs in vivo remains unclear, but it may account for the significant accumulation of platelets described in brain microvasculature of Malawian children who died from CM 11. In addition, the ability of clinical isolate cultures to clump in vitro was directly linked to the severity of disease in Malawian 12 and Mozambican patients 13, (although not in Malian 14).
With several aspects of the pRBC clumping phenotype poorly characterized, current studies on this subject have not followed a standardized procedure. This is an important issue because of the known high variability inherent in the assay 15. Here, we present a method for in vitro platelet-mediated clumping of P. falciparum with hopes that it will provide a platform for a consistent method for other groups and raise awareness of the limitations in investigating this phenotype in future studies. Being based in Malawi, we provide a protocol specifically designed for a limited resource setting, with the advantage that freshly collected clinical isolates can be examined for phenotype without need for cryopreservation.

A Simple Protocol for Platelet-mediated Clumping of Plasmodium falciparum-infected Erythrocytes in a Resource Poor Setting

This method investigates the platelet-mediated clumping phenotype of Plasmodium falciparum-infected erythrocytes (pRBC) in clinical isolates. This is performed by isolating and co-incubating platelet-rich plasma and a suspension of pRBC.

Un protocolo simple para el agrupamiento de plaquetas mediada por<em&gt; Plasmodium falciparum</emEritrocitos&gt; por el VIH en un recurso pobre ajuste

P. falciparum causes the majority of severe malarial infections. The pathophysiological mechanisms underlying cerebral malaria (CM) are not fully ...

Isolation and Analysis of Brain-sequestered Leukocytes from Plasmodium berghei ANKA-infected Mice

We describe a method for isolation and characterization of adherent inflammatory cells from brain blood vessels of P. berghei ANKA-infected mice. Infection of susceptible mouse-strains with this parasite strain results in the induction of experimental cerebral malaria, a neurologic syndrome that recapitulates certain important aspects of Plasmodium falciparum-mediated severe malaria in humans 1,2 . Mature forms of blood-stage malaria express parasitic proteins on the surface of the infected erythrocyte, which allows them to bind to vascular endothelial cells. This process induces obstructions in blood flow, resulting in hypoxia and haemorrhages 3 and also stimulates the recruitment of inflammatory leukocytes to the site of parasite sequestration.
Unlike other infections, i.e neutrotopic viruses4-6, both malaria-parasitized red blood cells (pRBC) as well as associated inflammatory leukocytes remain sequestered within blood vessels rather than infiltrating the brain parenchyma. Thus to avoid contamination of sequestered leukocytes with non-inflammatory circulating cells, extensive intracardial perfusion of infected-mice prior to organ extraction and tissue processing is required in this procedure to remove the blood compartment. After perfusion, brains are harvested and dissected in small pieces. The tissue structure is further disrupted by enzymatic treatment with Collagenase D and DNAse I. The resulting brain homogenate is then centrifuged on a Percoll gradient that allows separation of brain-sequestered leukocytes (BSL) from myelin and other tissue debris. Isolated cells are then washed, counted using a hemocytometer and stained with fluorescent antibodies for subsequent analysis by flow cytometry.
This procedure allows comprehensive phenotypic characterization of inflammatory leukocytes migrating to the brain in response to various stimuli, including stroke as well as viral or parasitic infections. The method also provides a useful tool for assessment of novel anti-inflammatory treatments in pre-clinical animal models.

Isolation and Analysis of Brain-sequestered Leukocytes from Plasmodium berghei ANKA-infected Mice

A method for isolation of adherent inflammatory leukocytes from brain blood vessels of Plasmodium berghei ANKA-infected mice is described. The method allows quantification as well as phenotypic characterization of isolated leukocytes after staining with fluorescent antibodies and subsequent analysis by flow cytometry.

Aislamiento y análisis de Brain-secuestrados Los leucocitos de<em&gt; Plasmodium berghei</em&gt; ANKA de ratones infectados

We describe a method for isolation and  characterization of adherent inflammatory cells from brain blood vessels of P. berghei ANKA-infected mice. ...

Automated Separation of C. elegans Variably Colonized by a Bacterial Pathogen

The wormsorter is an instrument analogous to a FACS machine that is used in studies of Caenorhabditis elegans, typically to sort worms based on expression of a fluorescent reporter. Here, we highlight an alternative usage of this instrument, for sorting worms according to their degree of colonization by a GFP-expressing pathogen. This new usage allowed us to address the relationship between colonization of the worm intestine and induction of immune responses. While C. elegans immune responses to different pathogens have been documented, it is still unknown what initiates them. The two main possibilities (which are not mutually exclusive) are recognition of pathogen-associated molecular patterns, and detection of damage caused by infection. To differentiate between the two possibilities, exposure to the pathogen must be dissociated from the damage it causes. The wormsorter enabled separation of worms that were extensively-colonized by the Gram-negative pathogen Pseudomonas aeruginosa, with the damage likely caused by pathogen load, from worms that were similarly exposed, but not, or marginally, colonized. These distinct populations were used to assess the relationship between pathogen load and the induction of transcriptional immune responses. The results suggest that the two are dissociated, supporting the possibility of pathogen recognition.

Automated Separation of C. elegans Variably Colonized by a Bacterial Pathogen

The wormsorter facilitates genetic screens in Caenorhabditis elegans by sorting worms according to expression of fluorescent reporters. Here, we describe a new usage:&#160;sorting according to colonization by a GFP-expressing pathogen, and we employ it to examine the poorly understood role of pathogen recognition in initiating immune responses.

La separación automatizada de<em&gt; C. elegans</em&gt; Variablemente colonizada por un patógeno bacteriano

The wormsorter is an instrument analogous to a FACS machine that is used in studies of Caenorhabditis elegans, typically to sort worms based on expression ...

High Yield Purification of Plasmodium falciparum Merozoites For Use in Opsonizing Antibody Assays

Plasmodium falciparum merozoite antigens are under development as potential malaria vaccines. One aspect of immunity against malaria is the removal of free merozoites from the blood by phagocytic cells. However assessing the functional efficacy of merozoite specific opsonizing antibodies is challenging due to the short half-life of merozoites and the variability of primary phagocytic cells. Described in detail herein is a method for generating viable merozoites using the E64 protease inhibitor, and an assay of merozoite opsonin-dependent phagocytosis using the pro-monocytic cell line THP-1. E64 prevents schizont rupture while allowing the development of merozoites which are released by filtration of treated schizonts. &#160;Ethidium bromide labelled merozoites are opsonized with human plasma samples and added to THP-1 cells. Phagocytosis is assessed by a standardized high throughput protocol. Viable merozoites are a valuable resource for assessing numerous aspects of P. falciparum biology, including assessment of immune function. Antibody levels measured by this assay are associated with clinical immunity to malaria in naturally exposed individuals. The assay may also be of use for assessing vaccine induced antibodies. &#160;

High Yield Purification of Plasmodium falciparum Merozoites For Use in Opsonizing Antibody Assays

Measuring antibody function is key to understanding immunity to Plasmodium falciparum malaria. This method describes the purification of viable merozoites, and measurement of opsonization-dependent phagocytosis by flow cytometry.

Alto Rendimiento Purificación de<em&gt; Plasmodium falciparum</em&gt; Los merozoitos Para uso en opsonizante Antibody Ensayos

Plasmodium falciparum merozoite antigens are under development as potential malaria vaccines. One aspect of immunity against malaria is the removal of ...

In Vivo Assessment of Rodent Plasmodium Parasitemia and Merozoite Invasion by Flow Cytometry

During blood stage infection, malaria parasites invade, mature, and replicate within red blood cells (RBCs). This results in a regular growth cycle and an exponential increase in the proportion of malaria infected RBCs, known as parasitemia. We describe a flow cytometry based protocol which utilizes a combination of the DNA dye Hoechst, and the mitochondrial membrane potential dye, JC-1, to identify RBCs which contain parasites and therefore the parasitemia, of in vivo blood samples from Plasmodium chabaudi adami DS infected mice. Using this approach, in combination with fluorescently conjugated antibodies, parasitized RBCs can be distinguished from leukocytes, RBC progenitors, and RBCs containing Howell-Jolly bodies (HJ-RBCs), with a limit of detection of 0.007% parasitemia. Additionally, we outline a method for the comparative assessment of merozoite invasion into two different RBC populations. In this assay RBCs, labeled with two distinct compounds identifiable by flow cytometry, are transfused into infected mice. The relative rate of invasion into the two populations can then be assessed by flow cytometry based on the proportion of parasitized RBCs in each population over time. This combined approach allows the accurate measurement of both parasitemia and merozoite invasion in an in vivo model of malaria infection.

In Vivo Assessment of Rodent Plasmodium Parasitemia and Merozoite Invasion by Flow Cytometry

The malaria parasite invades and replicates within red blood cells. The accurate assessment of merozoite invasion and parasitemia is therefore crucial in assessing the course of malaria infection. Here we describe a flow cytometry based protocol for the measurement of these parameters in a mouse model of malaria.

En la Evaluación in vivo de roedores Plasmodium parasitemia y Merozoite Invasión por Citometría de Flujo

During blood stage infection, malaria parasites invade, mature, and replicate within red blood cells (RBCs). This results in a regular growth cycle and an ...

Methods to Investigate the Regulatory Role of Small RNAs and Ribosomal Occupancy of Plasmodium falciparum

The genetic variation responsible for the sickle cell allele (HbS) enables erythrocytes to resist infection by the malaria parasite, P. falciparum. The molecular basis of this resistance, which is known to be multifactorial, remains incompletely understood. Recent studies found that the differential expression of erythrocyte microRNAs, once translocated into malaria parasites, affect both gene regulation and parasite growth. These miRNAs were later shown to inhibit mRNA translation by forming a chimeric RNA transcript via 5&#39; RNA fusion with discreet subsets of parasite mRNAs. Here, the techniques that were used to study the functional role and putative mechanism underlying erythrocyte microRNAs on the gene regulation and translational potential of P. falciparum, including the transfection of modified synthetic microRNAs into host erythrocytes, will be detailed.&#160; Finally, a polysome gradient method is used to determine the extent of translation of these transcripts. Together, these techniques allowed us to demonstrate that the dysregulated levels of erythrocyte microRNAs contribute to cell-intrinsic malaria resistance of sickle erythrocytes.

Methods to Investigate the Regulatory Role of Small RNAs and Ribosomal Occupancy of Plasmodium falciparum

Human microRNAs translocate from host erythrocytes to Plasmodium falciparum parasites. Here, the techniques used to transfect synthetic microRNAs into host erythrocytes and isolate all RNAs from P. falciparum are described. In addition, this paper will detail a method of polysome isolation in P. falciparum to determine the ribosomal occupancy and translational potential of parasite transcripts.

Métodos para investigar el papel de Regulación de pequeños ARN ribosomal y ocupación de<em&gt; Plasmodium falciparum</em

The genetic variation responsible for the sickle cell allele (HbS) enables erythrocytes to resist infection by the malaria parasite, P. falciparum. The ...

Bioluminescence Imaging to Detect Late Stage Infection of African Trypanosomiasis

Human African trypanosomiasis (HAT) is a multi-stage disease that manifests in two stages; an early blood stage and a late stage when the parasite invades the central nervous system (CNS). In vivo study of the late stage has been limited as traditional methodologies require the removal of the brain to determine the presence of the parasites.
Bioluminescence imaging is a non-invasive, highly sensitive form of optical imaging that enables the visualization of a luciferase-transfected pathogen in real-time. By using a transfected trypanosome strain that has the ability to produce late stage disease in mice we are able to study the kinetics of a CNS infection in a single animal throughout the course of infection, as well as observe the movement and dissemination of a systemic infection.
Here we describe a robust protocol to study CNS infections using a bioluminescence model of African trypanosomiasis, providing real time non-invasive observations which can be further analyzed with optional downstream approaches.

This manuscript describes the use of a bioluminescent strain of African trypanosomes to enable the tracking of late stage infection and demonstrates how in vivo live imaging can be used to visualize infections within the central nervous system in real-time.

Imágenes de bioluminiscencia para detectar la infección en fase tardía de la tripanosomiasis africana

Human African trypanosomiasis (HAT) is a multi-stage disease that manifests in two stages; an early blood stage and a late stage when the parasite invades ...

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