Expression of Exogenous Human Hepatic Nuclear Factor-1alpha by a Lentiviral Vector and Its Interactions with Plasmodium falciparum Subtilisin-Like Protease 2

The onset, severity, and ultimate outcome of malaria infection are influenced by parasite-expressed virulence factors as well as by individual host responses to these determinants. In both humans and mice, liver injury follows parasite entry, persisting to the erythrocytic stage in the case of infection with the fatal strain of Plasmodium falciparum. Hepatic nuclear factor (HNF)-1alpha is a master regulator of not only the liver damage and adaptive responses but also diverse metabolic functions. In this study, we analyzed the expression of host HNF-1alpha in relation to malaria infection and evaluated its interaction with the 5'-untranslated region of subtilisin-like protease 2 (subtilase, Sub2). Recombinant human HNF-1alpha expressed by a lentiviral vector (LV HNF-1alpha) was introduced into mice. Interestingly, differences in the activity of the 5'-untranslated region of the Pf-Sub2 promoter were detected in 293T cells, and LV HNF-1alpha was observed to influence promoter activity, suggesting that host HNF-1alpha interacts with the Sub2 gene.

Host vascular endothelial growth factor is trophic for Plasmodium falciparum-infected red blood cells.

Plasmodium falciparum, the protozoan parasite responsible for severe malaria infection, undergoes a complex life cycle. Infected red blood cells (iRBC) sequester in host cerebral microvessels, which underlies the pathology of cerebral malaria. Using immunohistochemistry on post mortem brain samples, we demonstrated positive staining for vascular endothelial growth factor (VEGF) on iRBC. Confocal microscopy of cultured iRBC revealed accumulation of VEGF within the parasitophorous vacuole, expression of host VEGF-receptor 1 and activated VEGF-receptor 2 on the surface of iRBC, but no accumulation of VEGF receptors within the iRBC. Addition of VEGF to parasite cultures had a trophic effect on parasite growth and also partially rescued growth of drug treated parasites. Both these effects were abrogated when parasites were grown in serum-free medium, suggesting a requirement for soluble VEGF receptor. We conclude that P. falciparum iRBC can bind host VEGF-R on the erythrocyte membrane and accumulate host VEGF within the parasitophorous vacuole, which may have a trophic effect on parasite growth.

Identification of Anopheles fauna in a hyperendemic falciparum area of Orissa State, India.

BACKGROUND & OBJECTIVE: Keonjhar district of Orissa State has been hyperendemic for falciparum malaria since many years with alarming deaths due to cerebral malaria. Therefore an entomological investigation to know more about the relative prevalence of Anopheles species was done. METHODS: Daytime indoor resting and outdoor resting, light trap and double bed net collections were made. Surveys were also made to collect Anopheles immature in streams and paddy fields. The Anopheles mosquitoes obtained by different catching methods were identified and the known vector species were subjected to gut and salivary gland dissection for vector incrimination. The infected specimens of An. fluviatilis and An. minimus were subjected to polymerase chain reaction assay for identification of sibling species. RESULTS: Of the anophelines collected, the most abundant was An. splendidus (18.2%) and An. fluviatilis (17.7%), followed by An. maculatus (14.0%) and An. minimus (9.0%). The sporozoite rate of An. fluviatilis and An. minimus was 0.9 and 1.4 respectively. The infected specimens have been identified as sibling species S of the An. fluviatilis complex and A of the An. minimus complex. INTERPRETATION & CONCLUSION: An. fluviatilis and An. minimus are the major two species in the transmission of malaria in Keonjhar district in Orissa.

El citocromo P-450 y la respuesta terapéutica a los antimaláricos / Cytochrome P-450 and the response to antimalarial drugs

OBJETIVOS: Evaluar la relación entre los factores genéticos y fenotípicos del sistema enzimático del citocromo P-450 y la respuesta terapéutica antimalárica a la cloroquina, la amodiaquina, la mefloquina y el proguanil, así como determinar la influencia de algunos factores biológicos y sociales del hospedero en el comportamiento de este complejo enzimático. MÉTODOS: Revisión sistemática de las bases de literatura biomédica PubMed, Excerpta Medica, LILACS y SciELO mediante descriptores en español e inglés. Se usaron los siguientes descriptores: "CYP-450" y "citocromo P-450" y sus combinaciones con "proguanil" (y lo mismo con "mefloquina", "cloroquina" y "amodiaquina"), "farmacocinética de proguanil" (y lo mismo con "mefloquina", "cloroquina" y "amodiaquina"), "resistencia a proguanil" (y lo mismo con "mefloquina", "cloroquina" y "amodiaquina"), "metabolismo", "farmacogenética", "enfermedad", "inflamación", "infección", "enfermedad hepática", "malaria", "nutrición" y "desnutrición". Estos mismos términos se usaron en inglés. La búsqueda se limitó a los artículos publicados en español, inglés y portugués hasta el 30 de junio de 2005 y a cuatro medicamentos antimaláricos: amodiaquina, cloroquina, mefloquina y proguanil. RESULTADOS: Algunos factores genéticos del citocromo P-450 humano (principalmente su polimorfismo), así como otros de tipo biológico y social (la propia presencia de enfermedad, inflamación o infección, la administración de medicamentos antimaláricos y su combinación, y el estado nutricional del paciente), influyen en la actividad de ese complejo enzimático. Solo en la última década se ha abordado el estudio de las bases genéticas de los citocromos y se han podido dilucidar los mecanismos de algunas interacciones entre fármacos y del metabolismo de estos, lo que ha permitido caracterizar el proceso de biotransformación de la amodiaquina y de la cloroquina. Se espera que nuevas investigaciones permitan responder a las interrogantes que aún subsisten, entre ellas cuál es la ruta metabólica de otros medicamentos antimaláricos, la distribución en la población de los alelos de las enzimas que participan en su metabolismo, y la contribución de tales mutaciones al fracaso terapéutico, y predecir la respuesta a los tratamientos antimaláricos...

Knob proteins in falciparum malaria.

Knob proteins play a significant role in the pathophysiology of cerebral malaria caused by Plasmodium falciparum. Most of these proteins are of parasite origin and can be divided into two major classes: (i) the cytoadherent proteins present at the surface of the knobs; and (ii) the submembranous structural proteins which are placed towards the cytoplasmic side in the knobs. Several surface proteins [viz., P. falciparum-infected erythrocyte membrane protein-1 (PFEMP-1), sequestrin, pfalhesin] and submembranous structural proteins [viz., knob-associated histidine-rich protein (KAHRP), PFEMP-2, PFEMP-3] of the knobs have been identified and characterized to a certain extent. The structural proteins interact with several host (e.g., spectrin, actin, band 4.1 etc.) as well as parasite (e.g., PFEMP-1) molecules to produce functional knobs. The surface proteins on the other hand interact with several adhesion molecules of the endothelial cell through receptor-ligand type of binding. Knob proteins are important from the point of view of malaria control since immunotherapeutic agents can be developed to block as well as reverse the cytoadherence phenomenon. The surface proteins are also good vaccine candidates except that they show a high rate of antigenic variation. Nevertheless, the use of ribozyme or antisense oligonucleotides to inhibit the expression of knob proteins (e.g., KAHRP alone or with surface protein) can be used as a molecular therapeutic agent.

Lipid peroxidation in acute falciparum malaria.

Lipid peroxidation was assessed by measuring malondialdehyde (MDA) in 30 patients with falciparum malaria and 20 controls (10 healthy adults and 10 patients of vivax malaria). Mean serum MDA was 0.96 +/- 0.38 nmol/ml, 1.1 +/- 0.17 nmol/ml and 2.9 +/- 1.1 nmol/ml in healthy controls, disease controls and falciparum malaria patients, respectively. Levels were significantly high (P less than 0.001) in patients with falciparum malaria. Higher values were associated with more number of complications and deaths.