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1.
Korean J Parasitol ; 59(2): 113-119, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33951766

RESUMEN

The computer vision diagnostic approach currently generates several malaria diagnostic tools. It enhances the accessible and straightforward diagnostics that necessary for clinics and health centers in malaria-endemic areas. A new computer malaria diagnostics tool called the malaria scanner was used to investigate living malaria parasites with easy sample preparation, fast and user-friendly. The cultured Plasmodium parasites were used to confirm the sensitivity of this technique then compared to fluorescence-activated cell sorting (FACS) analysis and light microscopic examination. The measured percentage of parasitemia by the malaria scanner revealed higher precision than microscopy and was similar to FACS. The coefficients of variation of this technique were 1.2-6.7% for Plasmodium knowlesi and 0.3-4.8% for P. falciparum. It allowed determining parasitemia levels of 0.1% or higher, with coefficient of variation smaller than 10%. In terms of the precision range of parasitemia, both high and low ranges showed similar precision results. Pearson's correlation test was used to evaluate the correlation data coming from all methods. A strong correlation of measured parasitemia (r2=0.99, P<0.05) was observed between each method. The parasitemia analysis using this new diagnostic tool needs technical improvement, particularly in the differentiation of malaria species.


Asunto(s)
Pruebas Diagnósticas de Rutina/métodos , Malaria Falciparum/diagnóstico , Malaria/diagnóstico , Plasmodium falciparum/química , Plasmodium knowlesi/química , Computadores , Pruebas Diagnósticas de Rutina/instrumentación , Eritrocitos/química , Eritrocitos/parasitología , Humanos , Malaria/parasitología , Malaria Falciparum/parasitología , Parasitemia/parasitología , Plasmodium falciparum/aislamiento & purificación , Plasmodium falciparum/fisiología , Plasmodium knowlesi/aislamiento & purificación , Plasmodium knowlesi/fisiología
2.
Am J Trop Med Hyg ; 104(2): 680-682, 2020 12 14.
Artículo en Inglés | MEDLINE | ID: mdl-33319732

RESUMEN

Invasion of Plasmodium knowlesi merozoite into human erythrocytes involves molecular interaction between the parasite's Duffy binding protein (PkDBPαII) and the Duffy antigen receptor for chemokines on the erythrocytes. This study investigates the binding activity of human erythrocyte with PkDBPαII of P. knowlesi isolates from high and low parasitemic patients in an erythrocyte binding assay. The binding activity was determined by counting the number and measuring the size of rosettes formed in the assay. The protein PkDBPαII of P. knowlesi isolated from low parasitemia cases produced significantly higher number of rosettes with human erythrocytes than high parasitemia case isolates (65.5 ± 12.9 and 17.2 ± 5.5, respectively). Interestingly, PkDBPαII of isolates from high parasitemia cases formed significantly larger rosettes with human erythrocytes than PkDBPαII of isolates from low parasitemia cases (18,000 ± 13,000 µm2 and 1,315 ± 623 µm2, respectively).


Asunto(s)
Antígenos de Protozoos/metabolismo , Eritrocitos/metabolismo , Parasitemia/parasitología , Plasmodium knowlesi/inmunología , Proteínas Protozoarias/metabolismo , Receptores de Superficie Celular/metabolismo , Antígenos de Protozoos/inmunología , Sistema del Grupo Sanguíneo Duffy , Humanos , Plasmodium knowlesi/química , Unión Proteica
3.
Parasit Vectors ; 11(1): 629, 2018 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-30541605

RESUMEN

BACKGROUND: In recent years, human infection by the simian malaria parasite Plasmodium knowlesi has increased in Southeast Asia, leading to growing concerns regarding the cross-species spread of the parasite. Consequently, a deeper understanding of the biology of P. knowlesi is necessary in order to develop tools for control of the emerging disease. TatD-like DNase expressed at the surface of P. falciparum has recently been shown to counteract host innate immunity and is thus a potential malaria vaccine candidate. METHODS: The expression of the TatD DNase of P. knowlesi (PkTatD) was confirmed by both Western-blot and immunofluorescent assay. The DNA catalytic function of the PkTatD was confirmed by digestion of DNA with the recombinant PkTatD protein in the presence of various irons. RESULTS: In the present study, we investigated the expression of the homologous DNase in P. knowlesi. The expression of TatD-like DNase in P. knowslesi (PkTatD) was verified by Western blot and indirect immunofluorescence assays. Like that of the P. falciparum parasite, PkTatD was also found to be located on the surface of erythrocytes infected by the parasites. Biochemical analysis indicated that PkTatD can hydrolyze DNA and this activity is magnesium-dependent. CONCLUSIONS: We identified that PkTatD expressed on the surface of P. knowlesi-infected RBCs is a Mg2+-dependent DNase and exhibits a stronger hydrolytic capacity than TatD from P. falciparum. The data support our previous findings that TatD-like DNase is a unanimously expressed virulence factor of Plasmodium parasites.


Asunto(s)
Desoxirribonucleasas/metabolismo , Plasmodium knowlesi/enzimología , Proteínas Protozoarias/metabolismo , Secuencia de Aminoácidos , ADN Protozoario/genética , ADN Protozoario/metabolismo , Desoxirribonucleasas/química , Desoxirribonucleasas/genética , Eritrocitos/parasitología , Humanos , Malaria Falciparum/parasitología , Plasmodium knowlesi/química , Plasmodium knowlesi/genética , Proteínas Protozoarias/química , Proteínas Protozoarias/genética , Alineación de Secuencia
4.
Parasitol Int ; 67(4): 481-492, 2018 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-29673877

RESUMEN

During development within the host erythrocyte malaria parasites generate nascent membranous structures which serve as a pathway for parasite protein transport to modify the host cell. The molecular basis of such membranous structures is not well understood, particularly for malaria parasites other than Plasmodium falciparum. To characterize the structural basis of protein trafficking in the Plasmodium knowlesi-infected erythrocyte, we identified a P. knowlesi ortholog of MAHRP2, a marker of the tether structure that connects membranous structures in the P. falciparum-infected erythrocyte. We show that PkMAHRP2 localizes on amorphous structures that connect Sinton Mulligan's clefts (SMC) to each other and to the erythrocyte membrane. Three dimensional reconstruction of the P. knowlesi-infected erythrocyte revealed that the SMC is a plate-like structure with swollen ends, reminiscent of the morphology of the Golgi apparatus. The PkMAHRP2-localized amorphous structures are possibly functionally equivalent to P. falciparum tether structure. These findings suggest a conservation in the ultrastructure of protein trafficking between P. falciparum and P. knowlesi.


Asunto(s)
Eritrocitos/parasitología , Plasmodium knowlesi/metabolismo , Proteínas Protozoarias/química , Proteínas Protozoarias/genética , Eritrocitos/química , Interacciones Huésped-Parásitos , Proteínas de la Membrana/análisis , Plasmodium falciparum/química , Plasmodium falciparum/metabolismo , Plasmodium knowlesi/química , Plasmodium knowlesi/genética , Transporte de Proteínas , Proteínas Protozoarias/metabolismo
5.
PLoS One ; 11(7): e0158998, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27391270

RESUMEN

Malaria remains a major health threat in many parts of the globe and causes high mortality and morbidity with 214 million cases of malaria occurring globally in 2015. Recent studies have outlined potential diagnostic markers and vaccine candidates one of which is the merozoite surface protein (MSP)-3. In this study, novel recombinant Plasmodium knowlesi MSP-3 was cloned, expressed and purified in an Escherichia coli system. Subsequently, the recombinant protein was evaluated for its sensitivity and specificity. The recombinant pkMSP-3 protein reacted with sera from patients with P. knowlesi infection in both Western blot (61%) and ELISA (100%). Specificity-wise, pkMSP-3 did not react with healthy donor sera in either assay and only reacted with a few non-malarial parasitic patient sera in the ELISA assay (3 of 49). In conclusion, sensitivity and specificity of pkMSP-3 was found to be high in the ELISA and Western Blot assay and thus utilising both assays in tandem would provide the best sero-diagnostic result for P. knowlesi infection.


Asunto(s)
Antígenos de Protozoos/inmunología , Malaria/diagnóstico , Malaria/inmunología , Plasmodium knowlesi/inmunología , Proteínas Protozoarias/inmunología , Adulto , Antígenos de Protozoos/química , Antígenos de Protozoos/genética , Western Blotting/métodos , Escherichia coli/genética , Femenino , Humanos , Malaria/genética , Masculino , Plasmodium knowlesi/química , Plasmodium knowlesi/genética , Proteínas Protozoarias/química , Proteínas Protozoarias/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología
6.
Mol Biochem Parasitol ; 190(2): 56-9, 2013 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23831369

RESUMEN

The myosin motor of the malaria parasite's invasion machinery moves over actin fibers while it is making critical contacts with the myosin-tail interacting protein (MTIP). Previously, in a "compact" Plasmodium falciparum MTIP•MyoA complex, MTIP domains 2 (D2) and 3 (D3) make contacts with the MyoA helix, and the central helix is kinked, but in an "extended" Plasmodium knowlesi MTIP•MyoA complex only D3 interacts with the MyoA helix, and the central helix is fully extended. Here we report the crystal structure of the compact P. knowlesi MTIP•MyoA complex. It appears that, depending on the pH, P. knowlesi MTIP can adopt either the compact or the extended conformation to interact with MyoA. Only at pH values above ~7.0, can key hydrogen bonds can be formed by the imidazole group of MyoA His810 with an aspartate carboxylate from the hinge of MTIP and a lysine amino group of MyoA simultaneously.


Asunto(s)
Proteínas del Citoesqueleto/química , Plasmodium knowlesi/química , Cristalografía por Rayos X , Proteínas del Citoesqueleto/metabolismo , Concentración de Iones de Hidrógeno , Modelos Moleculares , Plasmodium knowlesi/metabolismo , Unión Proteica , Conformación Proteica/efectos de los fármacos
7.
Int J Parasitol ; 40(11): 1257-68, 2010 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-20385136

RESUMEN

Cytidine diphosphate diacylglycerol synthase (CDS) diverts phosphatidic acid towards the biosynthesis of CDP-DAG, an obligatory liponucleotide intermediate in anionic phospholipid biosynthesis. The 78kDa predicted Plasmodium falciparum CDS (PfCDS) is recovered as a 50 kDa conserved C-terminal cytidylyltransferase domain (C-PfCDS) and a 28kDa fragment that corresponds to the unusually long hydrophilic asparagine-rich N-terminal extension (N-PfCDS). Here, we show that the two fragments of PfCDS are the processed forms of the 78 kDa pro-form that is encoded from a single transcript with no alternate translation start site for C-PfCDS. PfCDS, which shares 54% sequence identity with Plasmodium knowlesi CDS (PkCDS), could substitute for PkCDS in P. knowlesi. Experiments to disrupt either the full-length or the N-terminal extension of PkCDS indicate that not only the C-terminal cytidylyltransferase domain but also the N-terminal extension is essential to Plasmodium spp. PkCDS and PfCDS introduced in P. knowlesi were processed in the parasite, suggesting a conserved parasite-dependent mechanism. The N-PfCDS appears to be a peripheral membrane protein and is trafficked outside the parasite to the parasitophorous vacuole. Although the function of this unusual N-PfCDS remains enigmatic, the study here highlights features of this essential gene and its biological importance during the intra-erythrocytic cycle of the parasite.


Asunto(s)
Diacilglicerol Colinafosfotransferasa/química , Diacilglicerol Colinafosfotransferasa/metabolismo , Plasmodium falciparum/enzimología , Plasmodium knowlesi/enzimología , Proteínas Protozoarias/química , Proteínas Protozoarias/metabolismo , Secuencia de Aminoácidos , Animales , Chlorocebus aethiops , Citidina Difosfato Diglicéridos/biosíntesis , Diacilglicerol Colinafosfotransferasa/genética , Eritrocitos/parasitología , Humanos , Malaria/parasitología , Plasmodium falciparum/química , Plasmodium falciparum/genética , Plasmodium falciparum/crecimiento & desarrollo , Plasmodium knowlesi/química , Plasmodium knowlesi/genética , Plasmodium knowlesi/crecimiento & desarrollo , Estructura Terciaria de Proteína , Proteínas Protozoarias/genética
8.
Trends Biochem Sci ; 31(9): 487-91, 2006 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16876418

RESUMEN

Plasmodium vivax invasion of human erythrocytes requires that the ligand domain of the Duffy-binding protein (DBP) recognize its cognate erythrocyte receptor, making DBP a potential target for therapy. The recently determined crystal structure of the orthologous DBP ligand domain of the closely related simian malaria parasite Plasmodium knowlesi provides insight into the molecular basis for receptor recognition and raises important questions about the mechanism of immune evasion employed by the malaria parasite.


Asunto(s)
Antígenos de Protozoos/química , Plasmodium knowlesi/química , Proteínas Protozoarias/química , Receptores de Superficie Celular/química , Animales , Sitios de Unión , Cristalografía por Rayos X , Humanos , Ligandos , Modelos Moleculares , Plasmodium knowlesi/metabolismo , Plasmodium knowlesi/patogenicidad , Estructura Terciaria de Proteína , Receptores de Superficie Celular/metabolismo
9.
Nature ; 439(7077): 741-4, 2006 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-16372020

RESUMEN

Molecular processes that govern pathogenic features of erythrocyte invasion and cytoadherence in malaria are reliant on Plasmodium-specific Duffy-binding-like domains (DBLs). These cysteine-rich modules recognize diverse host cell-surface receptors during pathogenesis. DBLs of parasite erythrocyte-binding proteins mediate invasion, and those from the antigenically variant P. falciparum erythrocyte membrane protein 1 (PfEMP1) have been implicated in cytoadherence. The simian and human malarial parasites, P. knowlesi and P. vivax, invade human erythrocytes exclusively through the host DARC receptor (Duffy antigen receptor for chemokines). Here we present the crystal structure of the P. knowlesi DBL domain (Pkalpha-DBL), which binds to DARC during invasion of human erythrocytes. Pkalpha-DBL retains the overall fold observed in DBLs from P. falciparum erythrocyte-binding antigen (EBA)-175 (ref. 4). Mapping the residues that have previously been implicated in binding highlights a fairly flat but exposed site for DARC recognition in subdomain 2 of Pkalpha-DBL; this is in sharp contrast to receptor recognition by EBA-175 (ref. 4). In Pkalpha-DBL, the residues that contact DARC and the clusters of residues under immune pressure map to opposite surfaces of the DBL, and suggest a possible mechanism for immune evasion by P. vivax. Our comparative structural analysis of Pkalpha-DBL and P. falciparum EBA-175 provides a framework for the understanding of malaria parasite DBLs, and may affect the development of new prophylactic and therapeutic strategies.


Asunto(s)
Sistema del Grupo Sanguíneo Duffy/metabolismo , Plasmodium knowlesi/química , Plasmodium knowlesi/metabolismo , Secuencia de Aminoácidos , Animales , Sitios de Unión , Cristalografía por Rayos X , Disulfuros/metabolismo , Sistema del Grupo Sanguíneo Duffy/química , Eritrocitos/química , Eritrocitos/metabolismo , Humanos , Modelos Moleculares , Datos de Secuencia Molecular , Plasmodium falciparum/química , Plasmodium knowlesi/patogenicidad , Unión Proteica , Pliegue de Proteína , Estructura Terciaria de Proteína , Relación Estructura-Actividad
11.
Infect Immun ; 73(9): 5402-9, 2005 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16113256

RESUMEN

Proteins present on the surface of malaria parasites that participate in the process of invasion and adhesion to host cells are considered attractive vaccine targets. Aided by the availability of the partially completed genome sequence of the simian malaria parasite Plasmodium knowlesi, we have identified a 786-bp DNA sequence that encodes a 262-amino-acid-long protein, containing an altered version of the thrombospondin type I repeat domain (SPATR). Thrombospondin type 1 repeat domains participate in biologically diverse functions, such as cell attachment, mobility, proliferation, and extracellular protease activities. The SPATR from P. knowlesi (PkSPATR) shares 61% and 58% sequence identity with its Plasmodium falciparum and Plasmodium yoelii orthologs, respectively. By immunofluorescence analysis, we determined that PkSPATR is a multistage antigen that is expressed on the surface of P. knowlesi sporozoite and erythrocytic stage parasites. Recombinant PkSPATR produced in Escherichia coli binds to a human hepatoma cell line, HepG2, suggesting that PkSPATR is a parasite ligand that could be involved in sporozoite invasion of liver cells. Furthermore, recombinant PkSPATR reacted with pooled sera from P. knowlesi-infected rhesus monkeys, indicating that native PkSPATR is immunogenic during infection. Further efficacy evaluation studies in the P. knowlesi-rhesus monkey sporozoite challenge model will help to decide whether the SPATR molecule should be developed as a vaccine against human malarias.


Asunto(s)
Antígenos de Protozoos/genética , Proteínas de la Membrana/genética , Plasmodium knowlesi/genética , Proteínas Protozoarias/genética , Trombospondinas/química , Secuencia de Aminoácidos , Animales , Antígenos de Protozoos/metabolismo , Secuencia de Bases , Clonación Molecular , Técnica del Anticuerpo Fluorescente , Humanos , Proteínas de la Membrana/química , Proteínas de la Membrana/metabolismo , Datos de Secuencia Molecular , Plasmodium knowlesi/química , Señales de Clasificación de Proteína , Estructura Terciaria de Proteína , Proteínas Protozoarias/biosíntesis , Proteínas Protozoarias/química , Secuencias Repetitivas de Aminoácido , Alineación de Secuencia , Trombospondinas/genética
13.
Trop Med Int Health ; 4(4): 251-4, 1999 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-10320651

RESUMEN

Glutathione-S-transferase (GST) activity has been detected in rodent (Plasmodium berghei, P. yoelii), simian (P. knowlesi) and human (P. falciparum) malarial parasites, and in different intraerythrocytic stages of P. knowlesi (schizont > ring > trophozoite). In chloroquine-resistant strains of rodent and human malarial parasites GST activity significantly increases compared to sensitive strains. Further, the increase in enzyme activity is directly related to drug pressure of resistant P. berghei. Complete inhibition of chloroquine-sensitive and resistant P. berghei glutathione-S-transferase activities was observed at 2.5 and 5. micrometer concentration of hemin, respectively. An inverse relationship was found between the heme level and enzyme activity of chloroquine-resistant and sensitive P. berghei. Chloroquine, artemisinin, and primaquine noticeably inhibited GST activity in P. knowlesi.


Asunto(s)
Glutatión Transferasa/fisiología , Plasmodium berghei/enzimología , Plasmodium falciparum/enzimología , Plasmodium knowlesi/enzimología , Plasmodium yoelii/enzimología , Animales , Antimaláricos/metabolismo , Antimaláricos/farmacología , Cloroquina/metabolismo , Cloroquina/farmacología , Cricetinae , Resistencia a Medicamentos , Hemo/análisis , Hemo/fisiología , Humanos , Macaca mulatta/parasitología , Mesocricetus/parasitología , Ratones/parasitología , Plasmodium berghei/química , Plasmodium berghei/efectos de los fármacos , Plasmodium berghei/crecimiento & desarrollo , Plasmodium falciparum/química , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/crecimiento & desarrollo , Plasmodium knowlesi/química , Plasmodium knowlesi/efectos de los fármacos , Plasmodium knowlesi/crecimiento & desarrollo , Plasmodium yoelii/química , Plasmodium yoelii/efectos de los fármacos , Plasmodium yoelii/crecimiento & desarrollo , Protoporfirinas/análisis , Protoporfirinas/fisiología
14.
Exp Parasitol ; 91(3): 238-49, 1999 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-10072326

RESUMEN

We have identified a Plasmodium vivax merozoite surface protein (MSP) that migrates on SDS-polyacrylamide gels at a Mr of about 185 kDa. This protein was recognized by a P. vivax monoclonal antibody (mAb) that localizes the protein by immunofluorescence to the surface of merozoites and also immunoprecipitates this protein from NP-40 detergent extracts of [35S]methionine metabolically radiolabeled P. vivax schizonts. The P. vivax MSP does not become biosynthetically radiolabeled with [3H]glucoamine, [3H]myristate, [3H]palmitate, or [3H]mannose, indicating that this P. vivax MSP is not posttranslationally modified and bound to the merozoite membrane by a glycosylphosphatidylinositol (GPI) lipid anchor. Thus, in this respect, this protein is different from members of the MSP-1 protein family and from MSP-2 and MSP-4 of P. falciparum. The mAb cross-reacts with and outlines the surface of P. cynomolgi merozoites and immunoprecipitates a 150-kDa P. cynomolgi homologue. The mAb was used as an affinity reagent to purify the native homologous MSP from NP-40 extracts of P. cynomolgi mature schizonts in order to develop a specific polyclonal antiserum. The resulting anti-PcyMSP rabbit antiserum cross-reacts strongly with the P. vivax 185-kDa MSP and also recognizes an analogous 110-kDa protein from P. knowlesi. We have determined via an immunodepletion experiment that the 110-kDa P. knowlesi MSP corresponds to the PK 110 protein partially characterized earlier (Perler et al. 1987). The potential of P. vivax MSP as a vaccine candidate was addressed by conducting in vitro inhibition of erythrocyte invasion assays, and the IgG fraction of both the P. vivax MSP mAb and the P. cynomolgi MSP rabbit antiserum significantly inhibited entry of P. vivax merozoites. We denote, on a preliminary basis, these antigenically related merozite surface proteins PvMSP-185, PcyMSP-150, and PkMSP-110.


Asunto(s)
Proteína 1 de Superficie de Merozoito/análisis , Plasmodium cynomolgi/química , Plasmodium knowlesi/química , Plasmodium vivax/química , Animales , Anticuerpos Monoclonales/inmunología , Antígenos de Protozoos/análisis , Antígenos de Protozoos/inmunología , Antígenos de Superficie/análisis , Antígenos de Superficie/inmunología , Aotidae , Western Blotting , Electroforesis en Gel de Poliacrilamida , Eritrocitos/inmunología , Eritrocitos/parasitología , Técnica del Anticuerpo Fluorescente Indirecta , Humanos , Sueros Inmunes/inmunología , Macaca mulatta , Proteína 1 de Superficie de Merozoito/inmunología , Ratones , Microscopía Inmunoelectrónica , Plasmodium cynomolgi/inmunología , Plasmodium knowlesi/inmunología , Plasmodium vivax/inmunología , Pruebas de Precipitina , Conejos , Saimiri
15.
Mol Biochem Parasitol ; 93(2): 295-308, 1998 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-9662713

RESUMEN

Movement of the malaria parasite into a host erythrocyte during invasion is thought to involve polymerization of parasite actin. We have used F-actin affinity chromatography to isolate actin-binding proteins from Plasmodium knowlesi merozoites, in an attempt to identify proteins responsible for regulating parasite actin polymerization during invasion. Five major proteins, of molecular masses 75, 70, 48, 40 and 34 kDa, were reproducibly eluted from the F-actin columns. The 70 kDa actin-binding protein was identified by tryptic peptide microsequencing as heat shock protein-70 kDa (HSC70); this identification was confirmed by Western blotting with anti-HSC70 antibody, and binding of the protein to ATP-agarose. A doublet of 32/34-kDa proteins coeluted with parasite HSC70 from the F-actin and ATP-agarose columns; a complex of these three proteins was also observed by gel filtration chromatography Highly enriched fractions containing the Plasmodium HSC70/32/34 complex inhibited the polymerization of rabbit skeletal muscle actin, in vitro. This capping activity was calcium-independent, and abrogated by phosphatidylinositol 4,5-bisphosphate. The average length of the actin filaments polymerized in presence of the HSC70/32/34-kDa complex was significantly shorter than in the absence of the complex, consistent with a capping activity. The capping or uncapping of actin filament ends by the HSC70/32/34-kDa complex during invasion could provide a mechanism for localized actin filament growth and movement of the parasite into the host cell.


Asunto(s)
Actinas/metabolismo , Proteínas HSP70 de Choque Térmico/análisis , Proteínas de Microfilamentos/análisis , Plasmodium knowlesi/química , Proteínas Protozoarias/análisis , Actinas/química , Secuencia de Aminoácidos , Animales , Biopolímeros , Cromatografía de Afinidad , Cromatografía en Gel , Proteínas HSP70 de Choque Térmico/química , Proteínas HSP70 de Choque Térmico/aislamiento & purificación , Proteínas HSP70 de Choque Térmico/metabolismo , Proteínas de Microfilamentos/química , Proteínas de Microfilamentos/aislamiento & purificación , Proteínas de Microfilamentos/metabolismo , Datos de Secuencia Molecular , Peso Molecular , Plasmodium knowlesi/metabolismo , Proteínas Protozoarias/química , Proteínas Protozoarias/aislamiento & purificación , Proteínas Protozoarias/metabolismo
16.
Am J Trop Med Hyg ; 55(6): 635-41, 1996 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-9025690

RESUMEN

The circumsporozoite antigen (CS) of the simian malarial parasite Plasmodium knowlesi consists of tandemly repeated immunodominant peptide units that are variable and may play a role in evading the immune system. To study the immunogenicity of this antigen in the absence of the immunodominant repeats, the entire nonrepetitive region of the antigen was expressed in Escherichia coli as two fusion proteins with glutathione-S-transferase (GST) representing the amino terminal (GST-CSN) and the carboxy terminal domains (GST-CSC) of the CS antigen. The immunogenicity of these fusion proteins was studied in rabbits and different strains of mice. Antibody raised against both the CSN and CSC domains in both rabbits and every strain of mice recognized the native protein, as detected by immunofluorescence assay (IFA) using P. knowlesi sporozoites. A positive IFA reaction was also obtained with P. vivax sporozoites using antisera raised against the CSC domain. High titer antisera were raised in rabbits against both the domains, whereas mice showed comparatively low titers. On Western blots, mice showed specific response against the CSC domain. In both rabbits and mice, significant titers of antibodies were raised against region II, which has been shown to be the putative sporozoite binding site for hepatocytes in the case of P. falciparum.


Asunto(s)
Antígenos de Protozoos/inmunología , Plasmodium knowlesi/inmunología , Proteínas Protozoarias/inmunología , Secuencia de Aminoácidos , Animales , Anticuerpos Antiprotozoarios/biosíntesis , Anticuerpos Antiprotozoarios/inmunología , Antígenos de Protozoos/química , Western Blotting , Ensayo de Inmunoadsorción Enzimática , Femenino , Técnica del Anticuerpo Fluorescente , Sueros Inmunes/inmunología , Ratones , Ratones Endogámicos , Datos de Secuencia Molecular , Plasmodium knowlesi/química , Proteínas Protozoarias/química , Conejos , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/inmunología
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