The objective of this study was to construct and express recombinant prokaryotic plasmid pET32a (+)- ast1 in E. coli BL21(DE3). Amastin gene was amplified from genomic DNA of Leishmania Donovani and its transmembran region was predicted by the methods of SOSUI and Tmpred; astl located in N-terminus of amastin gene was amplified and cloned into prokaryotic plasmid pET32a(+), which was named pET32a(+)-ast1, and then rAST1 was expressed in E. coli BL21(DE3). The results of SDS-PAGE and immunobloting assay showed that a fusion protein rAST1 (relative molecular mass about 27 kDa) was able to express in BL21. The recombinant prokaryotic plasmid pET32a(+)- ast1 was successfully constructed, and noted to be efficiently expressed in E. coli BL21(DE3).
Animals ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Extracellular Space ; Genes, Protozoan ; Leishmania donovani ; genetics ; Plasmids ; genetics ; Protozoan Proteins ; biosynthesis ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics

OBJECTIVETo characterize the immune response induced by SAG1 encoding plasmid combined with IL-2 gene adjuvant in mice and to assess the protective effect of this vaccination against toxoplasmosis.

METHODSMice were co-injected intramuscularly with plasmid encoding Toxoplasma gondii SAG1 plus murine IL-2 expression vector at a dose of 100 microg. Booster immunizations were employed 2 more times at 3-week interval. As controls, mice were inoculated with PBS or empty plasmid pcDNA3. Humoral and cellular responses were assayed using ELISA for the determination of Ab, Ab isotype and IFN-gamma, as well as IL-4. To detect the integration and dissemination of DNA in the injected mice, PCR and in situ hybridization were performed. All mice were then infected with highly virulent RH tachyzoites of Toxoplasma gondii intraperitoneally.

RESULTSSignificant increases in specific IgG levels were observed in mice after immunization three times with SAG1 expression plasmid. With respect to the IgG isotype, co-inoculation of IL-2 expression plasmid enhanced the level of IgG2a and the production of IFN-gamma. Challenging mice by vaccinating with combined plasmids with RH tachyzoites resulted in prolonged survival.

CONCLUSIONHumoral and cytokine responses elicited by SAG1 DNA immunization can be modulated by co-inoculation with IL-2 expression plasmid. The use of DNA vaccine in combination with an appropriate cytokine gene to prevent T. gondii infection warrants further investigation.

Animals ; Antibodies, Protozoan ; blood ; Antigens, Protozoan ; Cytokines ; biosynthesis ; Female ; Immunization ; Immunoglobulin G ; blood ; classification ; Interleukin-2 ; genetics ; Mice ; Protozoan Proteins ; genetics ; Protozoan Vaccines ; immunology ; Toxoplasma ; immunology ; Toxoplasmosis, Animal ; prevention & control ; Vaccines, DNA ; immunology

Phenylalany--tRNA synthetase is a key enzyme for protein synthesis in Trypanosoma. Its validation as an inhibition. target will enable the development of a new generation of anti-Trypanosoma drugs. However, little is known about the isolation of the Trypanosoma Phenylalanyl-tRNA synthetase. Here we report the cloning, expression, purification, and activity assay of Phenylalanyl-tRNA synthetase from Trypanosoma brucei in Escherichia coli host. We co-cloned the alpha-subunit and beta-subunit of Phenylalanyl-tRNA synthetase from Trypanosoma brucei genomic DNA into the co-expression vector pCOLADuet. We successfully expressed the Trypanosoma brucei Phenylalanyl-tRNA synthetase in E. coli host, purified the whole enzyme by Ni-Hind affinity column and verified it by Western blotting. In addition, we tested its enzymatic activity by isotope labeling. The whole work laid a solid foundation for in vitro the screening and optimization of Trypanosoma brucei phenylalanyl-tRNA synthetase inhibitors.
Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Phenylalanine-tRNA Ligase ; biosynthesis ; genetics ; Protozoan Proteins ; biosynthesis ; genetics ; Recombinant Proteins ; biosynthesis ; genetics ; metabolism ; Trypanosoma brucei brucei ; enzymology ; genetics

OBJECTIVETo construct a recombinant prokaryotic expression vector (plasmid) containing microneme protein 1 (MIC1) partial gene in toxoplasma gondii (T. gondii) ZS2 isolate. The gene was expressed in varied Escherichia coli (E. coli) after sequencing.

METHODSThe gene fragment coding MIC 1 from the genomic DNA of T. gondii ZS2 isolate was amplified by polymerase chain reaction (PCR). The gene was inserted to a prokaryotic expression vector pWR450-1 by digesting with restriction enzymes and linking reaction. The positive clone was screened on LB plates containing ampicillin and identified by restrictive enzyme digestion, PCR amplification and sequence analysis. The recombinant plasmid was transferred into E. coli TG1, JM109 (DE3) and DH5 alpha, and was expressed under the induction of IPTG. The expression products were identified by SDS-PAGE. The MIC1 gene structure was analyzed and compared in homology with the gene sequence of RH isolate using computer software.

RESULTSThe recombinant plasmid pWR450-1/MIC1, after cloning from acquired 471 bp MIC1 gene fragment and amplified from the genome gene ZS2, was complete homologous to the sequence of RH isolate, reflecting its highly conservative. The gene could be expressed as fusion protein with 70,000 in varied E. coli.

CONCLUSIONRecombinant plasmid pWR450-MIC1 was successfully constructed and could be expressed in different strains of E. coli, laying a foundation for research on its structure and function.

Animals ; Base Sequence ; Cell Adhesion Molecules ; biosynthesis ; genetics ; Cloning, Molecular ; DNA, Protozoan ; analysis ; Escherichia coli ; genetics ; Gene Expression ; Molecular Sequence Data ; Nucleic Acid Amplification Techniques ; Protozoan Proteins ; biosynthesis ; genetics ; Recombinant Proteins ; biosynthesis ; genetics ; Toxoplasma ; genetics

Toxoplasmic encephalitis is caused by reactivation of bradyzoites to rapidly dividing tachyzoites of the apicomplexan parasite Toxoplasma gondii in immunocompromised hosts. Diagnosis of this life-threatening disease is problematic, because it is difficult to discriminate between these 2 stages. Toxoplasma PCR assays using gDNA as a template have been unable to discriminate between an increase or decrease in SAG1 and BAG1 expression between the active tachyzoite stage and the latent bradyzoite stage. In the present study, real-time RT-PCR assay was used to detect the expression of bradyzoite (BAG1)- and tachyzoite-specific genes (SAG1) during bradyzoite/tachyzoite stage conversion in mice infected with T. gondii Tehran strain after dexamethasone sodium phosphate (DXM) administration. The conversion reaction was observed in the lungs and brain tissues of experimental mice, indicated by SAG1 expression at day 6 after DXM administration, and continued until day 14. Bradyzoites were also detected in both organs throughout the study; however, it decreased at day 14 significantly. It is suggested that during the reactivation period, bradyzoites not only escape from the cysts and reinvade neighboring cells as tachyzoites, but also converted to new bradyzoites. In summary, the real-time RT-PCR assay provided a reliable, fast, and quantitative way of detecting T. gondii reactivation in an animal model. Thus, this method may be useful for diagnosing stage conversion in clinical specimens of immunocompromised patients (HIV or transplant patients) for early identification of tachyzoite-bradyzoite stage conversion.
Animals ; Antigens, Protozoan/*biosynthesis ; Brain/parasitology ; Female ; *Gene Expression ; Heat-Shock Proteins/*biosynthesis ; Immunocompromised Host ; Life Cycle Stages ; Lung/parasitology ; Mice ; Protozoan Proteins/*biosynthesis ; Real-Time Polymerase Chain Reaction ; Toxoplasma/*genetics/physiology ; Toxoplasmosis, Animal

OBJECTIVETo develop a technology for production of recombinant SAG1 of Toxoplasma gondii (T.g) in batches.

METHODSThe rSAG1 of T.g was expressed in E.coli by high-density fermentation and purified by Sephadex G-75 column chromatography after Ni-NTA agarose at native condition. The activity of rSAG1 and its efficacy in T.g diagnosis were identified by Western blotting and ELISA, respectively.

RESULTSThe optical density (OD) of the bacteria reached 20.21 after induction, and 300 g bacteria were harvested from 11.5 L broth. The rSAG1 was highly expressed in E.coli as a fusion protein, accounting for about 25.82% of the total bacterial protein. The purity of rSAG1 reached 98.54% after purification by Ni-NTA combined with Sephadex G-75 column chromatography. Western blotting revealed a distinct band reacting with the sera of rabbits vaccinated by T.g. Twenty-four of the 25 sera of mice infected with T.g and 36 of the 38 sera of human subjects with IgG antibody against T.g were detected by rSAG1-ELISA.

CONCLUSIONA large-scale production of immunoreactive SAG1 of T.g is developed by high-density fermentation and purification with Ni-NTA combined with Sephadex G-75 column chromatography.

Animals ; Antigens, Protozoan ; biosynthesis ; genetics ; immunology ; Antigens, Surface ; immunology ; Blotting, Western ; Enzyme-Linked Immunosorbent Assay ; Escherichia coli ; genetics ; metabolism ; Fermentation ; Protozoan Proteins ; biosynthesis ; genetics ; immunology ; Recombinant Fusion Proteins ; biosynthesis ; immunology ; isolation & purification ; Toxoplasma ; immunology

OBJECTIVETo establish an tachyzoite-brachyzoite interconversion system for Toxoplasma gondii RH strain in vitro.

METHODSCOS-7 cells were inoculated with purified tachyzoites of T.gondii RH strain and cultured in vitro. The morphology of the cultured cells and parasites was observed and the total cellular RNA extracted on days 1 to 6 following the inoculation for detecting the expression of tachyzoite-specific protein (SAG1) and bradyzoite-specific proteins (BAG1 and SAG2C) using RT-PCR.

RESULTSWith the passage of time, the number of parasites in COS-7 cells increased but the proliferation rate was lowered gradually. The intracellular tachyzoites proliferated by means of budding and binary fission, which led to the changes in the alignment of the parasites in the cells from curved pairs, rosette or clustered, and semi-circular patterns to spherical encapsulation-like structures. These changes indicated the gradual transformation of the tachyzoites into bradyzoites. The expressions of the tachyzoite-specific SAG1 gene were detected throughout the 6 days of in vitro culture. The expression of the bradyzoite-specific BAG1 gene had been detected since the second day after the inoculation and SAG2C gene since the fifth day. Alteration of the culture condition resulted in gradual transformation of the bradyzoites into tachyzoites.

CONCLUSIONAn in vitro tachzoites-bradyzoite interconversion system for T.gondii has been successfully established, which provides the basis for further study of the mechanism of interconversion.

Animals ; COS Cells ; Cell Culture Techniques ; Cercopithecus aethiops ; Cysts ; Female ; Genes, Protozoan ; genetics ; Host-Parasite Interactions ; Mice ; Protozoan Proteins ; biosynthesis ; genetics ; Toxoplasma ; growth & development ; physiology

OBJECTIVETo identify and clone the gene named pfstom gene which encoding the protein belonging to band 7 family and to do primary research on its function.

METHODSBased on the finished data in international public malaria database, coding sequence of pfstom cDNA was obtained by RT-PCR from FCC1/HN. Its phylogenetic profiles and the homogeny were analyzed by some softwares. After Prokaryotic expression, C terminal of Pfstom protein was expressed by Pet30a system. Recombinant Pfstom protein was used to immol/Lunize rabbit and then serum was harvested and the IgG was purified for Western blot.

RESULTSThe coding sequence of pfstom is 1,125 bp which encoding 374 amino acids with C-terminal fragment being homogenous to stomatin-like protein which belongs to band 7 family. Phylogenetic profiles analysis revealed its homogeny to stomatin. Western blot showed its stage-specific expression in trophozoite.

CONCLUSIONPfstom belongs to band-7 family. It was expressed specifically in trophozoite in erythrocyte stage of plasmodium falciparum. It was not expressed in ring stage. And it is membrane-related protein. All these results provided the foundation for further research on pfstom.

Amino Acid Sequence ; Animals ; Blood Proteins ; biosynthesis ; genetics ; immunology ; DNA, Complementary ; genetics ; Membrane Proteins ; biosynthesis ; genetics ; immunology ; Molecular Sequence Data ; Phylogeny ; Plasmodium falciparum ; chemistry ; genetics ; pathogenicity ; Protozoan Proteins ; biosynthesis ; genetics ; immunology ; Rabbits ; Recombinant Proteins ; biosynthesis ; genetics

Trypanosoma brucei, a protozoan parasite, causes sleeping sickness in humans and Nagana disease in domestic animals in central Africa. The trypanosome surface is extensively covered by glycosylphosphatidylinositol (GPI)-anchored proteins known as variant surface glycoproteins and procyclins. GPI anchoring is suggested to be important for trypanosome survival and establishment of infection. Trypanosomes are not only pathogenically important, but also constitute a useful model for elucidating the GPI biosynthesis pathway. This review focuses on the trypanosome GPI biosynthesis pathway. Studies on GPI that will be described indicate the potential for the design of drugs that specifically inhibit trypanosome GPI biosynthesis.
Animals ; Biosynthetic Pathways ; Glycosylphosphatidylinositols/*biosynthesis/chemistry ; Humans ; Protozoan Proteins/genetics/metabolism ; Trypanosoma brucei brucei/chemistry/genetics/*metabolism ; Trypanosomiasis, African/*parasitology

Trypanosoma brucei, a protozoan parasite, causes sleeping sickness in humans and Nagana disease in domestic animals in central Africa. The trypanosome surface is extensively covered by glycosylphosphatidylinositol (GPI)-anchored proteins known as variant surface glycoproteins and procyclins. GPI anchoring is suggested to be important for trypanosome survival and establishment of infection. Trypanosomes are not only pathogenically important, but also constitute a useful model for elucidating the GPI biosynthesis pathway. This review focuses on the trypanosome GPI biosynthesis pathway. Studies on GPI that will be described indicate the potential for the design of drugs that specifically inhibit trypanosome GPI biosynthesis.
Animals ; Biosynthetic Pathways ; Glycosylphosphatidylinositols/*biosynthesis/chemistry ; Humans ; Protozoan Proteins/genetics/metabolism ; Trypanosoma brucei brucei/chemistry/genetics/*metabolism ; Trypanosomiasis, African/*parasitology