Characterisation of a cyclophilin isoform in Trypanosoma cruzi.

The immunosuppressive drug cyclosporin A (CsA) has shown antiparasitic activity against several protozoans and helminths, when complexed to proteins called cyclophilins (CyPs). In this paper, the molecular characterisation of one member of the CyP family in Trypanosoma cruzi is reported. TcCyP19 gene proved to be highly conserved compared to CyPs from other organisms and was highly homologous to a Trypanosoma brucei brucei CyPA. This gene was expressed in Escherichia coli and the purified recombinant protein exhibited a peptidyl prolyl cis-trans isomerase activity that was inhibited by CsA (IC(50) = 18.4 + /-0.8 nM). The TcCyP19 gene was located on two chromosomal bands in T. cruzi CL Brener clone.

The tyrosine aminotransferase from Trypanosoma rangeli: sequence and genomic characterization.

The complete sequence and genomic characterization of the tyrosine aminotransferase (TAT) gene from Trypanosoma rangeli is reported. The gene was found to be organized in a tandem multicopy gene array. A homologous mRNA species (2.5 kb) was identified in the epimastigote form of the parasite. From the deduced amino acid sequence, the gene encodes a protein of 420 amino acids with a predicted molecular mass of 46.4 kDa and a theoretical pI of 6.23. A high sequence identity was found with the Trypanosoma cruzi, human and rat enzymes. All the essential residues for TAT enzymatic activity are conserved, as well as a pyridoxal-phosphate attachment site typical of class-I aminotransferases. The recombinant enzyme was recognized by a monoclonal antibody against the T. cruzi enzyme. Additionally, the recombinant protein showed enzymatic activity when incubated with L-tyrosine and 2-oxoglutaric acid as substrates.

Molecular cloning, sequencing and expression of a serine proteinase inhibitor gene from Toxoplasma gondii.

A cDNA clone from a Toxoplasma gondii tachyzoite cDNA library encoding a serine proteinase inhibitor (serpin) was isolated. The 1376 bp cDNA sequence encodes a 294 amino acid protein with a putative signal peptide of 23 amino acids resulting in a mature protein with a predicted mass of 30,190 Da and a pI of 4.86. This protein has internal sequence similarity of residues 30-66, 114-150, 181-217 and 247-283 indicating a four-domain structure. The four domains exhibit high identity to serine proteinase inhibitors belonging to the non-classical Kazal-type family. The gene is single copy in the tachyzoite haploid genome of RH strain and was amplified by polymerase chain reaction (PCR). Several introns were identified. The sequence encoding the mature protein was amplified by PCR, cloned into the pQE30 vector and expressed in Escherichia coli. Specific antiserum generated against the recombinant protein was used in immunoblot assay and two bands of 38 and 42 kDa were detected in a whole parasite homogenate. The recombinant protein showed trypsin-inhibitory activity, one of the two potential specificities. We discuss the possible roles that T. gondii serpin(s) may play in the survival of the tachyzoites in the host.

Trypanosoma rangeli and Trypanosoma cruzi: molecular characterization of genes encoding putative calcium-binding proteins, highly conserved in trypanosomatids.

Genes encoding a 29-kDa flagellar calcium-binding protein (F29) in Trypanosoma cruzi, strongly homologous to EF-hand calcium-binding protein-encoding genes previously reported in this parasite, were isolated by immunoscreening. F29 is encoded by a number of very similar genes, highly conserved among different T. cruzi isolates. The genes are located on a pair of homologous chromosomes, arranged in one or two clusters of tandem repeats. PCR amplification of Trypanosoma rangeli genomic DNA, using primers derived from the T. cruzi F29 sequence made it possible to isolate the homologous gene in T. rangeli, encoding a 23-kDa protein called TrCaBP. Gene sequence comparisons showed homology to EF-hand calcium-binding proteins from T. cruzi (82.8%), Trypanosoma brucei brucei (60.2%), and Entamoeba histolytica (28.4%). Northern blot analysis revealed that the TrCaBP gene is expressed in T. rangeli as a polyadenylated transcript. The TrCaBP-encoding genes are present in at least 20 copies per cell, organized in tandem arrays, on large T. rangeli chromosomes in some isolates and on two smaller ones in others. This gene, however, seems to be absent from Leishmania.

Trypanosoma cruzi exoantigen is a member of a 160 kDa gene family.

During the chronic stage of Chagas disease a 160 kDa antigen appears in the blood of patients and remains detectable many years after the onset of the disease. This antigen is secreted by the trypomastigote form of the parasite while it is undetectable in the epimastigote form. We report here that the chronic 160 kDa exoantigen is encoded by a gene family (CEA 160 family). We describe the cloning and partial nucleotide sequence of a gene (CEA 160-1) belonging to the CEA160 family. Comparison of the gene sequence with other sequences present in the databases revealed homologies with several Trypanosoma cruzi surface antigens. Highest amino acid identity (59%) was with members of a family containing epitopes that mimic nervous tissues (Van Voorhis et al. 1993). Another related group (18-22% amino acid identity) comprises proteins of 85 or 160 kDa sharing an amino acid motif that is conserved among bacterial neuraminidases (Fouts et al. 1991; Pollevick et al. 1991; Kahn et al. 1991; Takle & Cross, 1991; Franco et al. 1993). The amino acid identities with the different antigens were not homogeneously distributed. Regions of higher identity (40-60%) were grouped in the central region of each protein.

Isolation and characterization of a gene from Trypanosoma cruzi encoding a 46-kilodalton protein with homology to human and rat tyrosine aminotransferase.

The complete sequence of a gene encoding a 46-kDa protein of Trypanosoma cruzi is presented. The first ATG complies with the consensus sequence for initiation of translation. A single band of 2 kb was highlighted by hybridizing a probe from the 46-kDa protein gene to a Northern filter containing total T. cruzi RNA. The gene is present in 50-80 copies per cell and most of them are contained in 2 tandem arrays on large T. cruzi chromosomes (> 2000 kb). A strong homology with rat and human tyrosine aminotransferase was detected. Homology with a Trypanosoma brucei retrotransposon was found in the nonsense strand of the intergenic region.

Trypanosoma cruzi: cellular and antibody response against the parasite in mice immunized with a 19-amino acid synthetic peptide.

Several monoclonal antibodies were prepared against the flagellar fraction of Trypanosoma cruzi epimastigotes (Tulahuén strain, stock Tul 2). One of them, FCH-F8-4, has previously shown biologic activity against the parasite (complement-mediated lysis and neutralization of the trypomastigote infectivity). Immunopurified antigens using this monoclonal antibody elicited a protective immune response in mice. Two recombinant cDNA clones were detected with this anti-flagellar fraction monoclonal antibody on a lambda gt11 expression library prepared from T. cruzi epimastigote mRNA. The insert of one of these cDNA clones, lambda(FCH-F8-4)1 (150 bp) coded for a 19-amino acid peptide (PAFLGCSSRFSGSFSGVEP). This insert hybridized with a 5.0-kb mRNA from epimastigotes. The beta-galactosidase fusion protein was produced in lysogenic bacteria. The monoclonal antibody recognized the epitope present in the fusion protein after western blotting of the crude lysate. A synthetic peptide (SP4) containing the complete sequence of lambda(FCH-F8-4)1 was constructed on solid phase. This peptide was able to inhibit the ELISA reactivity (in a range from 13 to 52%) of flagellar fraction immunized mouse sera and when administered (coupled to KLH or alone) to BALB/c mice with Bordetella pertussis as adjuvant, it induced a humoral and cellular immune response which was detected by ELISA, immunofluorescence, blotting, and DTH reactions against T. cruzi antigens. The immune response obtained indicates that this synthetic peptide resembles the parasite antigen conformation and could be useful for diagnosis purposes or be able to elicit immunoprotection against T. cruzi infection.

Bases moleculares e inmunológicas para el desarrollo de una vacuna contra la enfermedad de Chagas / Molecular and immunological bases for the development of a vaccine against Chagas'disease

Diferentes fracciones subcelulares de epimastigotes de T.cruzi fueron ensayadas en su capacidad de inducir protección o agresión en animales experimentales. La fracción flagelar (F) tuvo las mejores propiedades protectoras, sin efectos agresivos sobre los tejidos. Se prepararon varios anticuerpos monoclonales contra esta fracción. Dos de ellos, FCH-F8-1 y 4, mostraron capacidad de neutralizar la infectividad de tripomastigotes sanguíneos, de producir la lisis mediada por complemento de tripomastigotes de cultivo y de reconocer antígenos de la superfície de ambas formas epi y tripomastigotes. El anticuerpo FCH-F8-1, reconoce por inmunoprecipitación, una proteína de 85 kDa en tripomastigotes, mientras que en "blotting" reaccionó con una molécula de 43 kDa, en ambas formas del parásito. El otro anticuerpo, FCH-F8-4 reaccionó por esta última técnica, con varias proteínas de peso molecular entre 50 y 150 kDa, en epimastigotes y sólo con dos (15 y 48 kDa) en tripomastigotes. Ratones inmunizados con antígenos purificados por cromatografia de afinidad usando FCH-F8-4, fueron protegidos contra el desafio de formas infectantes. En una biblioteca de ADNc de epimastigotes de T. cruzi construída en el vector I gt11 se detectaron varios clones, tres con FCH-F8-4 y dos con FCH-F8-1. Dos clones, uno de cada grupo fueron estudiados, y (FCH-F8-1) 1 y (FCH-F8-4) 1. El tamaño de los insertos para ambos fue de 150 pares de bases y utilizados como sondas detectaron ARNm de epimastigotes de 3,5 y 5,0...

Bases moleculares e inmunológicas para el desarrollo de una vacuna contra la enfermedad de Chagas / Molecular and immunological bases for the development of a vaccine against Chagasdisease

Diferentes fracciones subcelulares de epimastigotes de T.cruzi fueron ensayadas en su capacidad de inducir protección o agresión en animales experimentales. La fracción flagelar (F) tuvo las mejores propiedades protectoras, sin efectos agresivos sobre los tejidos. Se prepararon varios anticuerpos monoclonales contra esta fracción. Dos de ellos, FCH-F8-1 y 4, mostraron capacidad de neutralizar la infectividad de tripomastigotes sanguíneos, de producir la lisis mediada por complemento de tripomastigotes de cultivo y de reconocer antígenos de la superfície de ambas formas epi y tripomastigotes. El anticuerpo FCH-F8-1, reconoce por inmunoprecipitación, una proteína de 85 kDa en tripomastigotes, mientras que en "blotting" reaccionó con una molécula de 43 kDa, en ambas formas del parásito. El otro anticuerpo, FCH-F8-4 reaccionó por esta última técnica, con varias proteínas de peso molecular entre 50 y 150 kDa, en epimastigotes y sólo con dos (15 y 48 kDa) en tripomastigotes. Ratones inmunizados con antígenos purificados por cromatografia de afinidad usando FCH-F8-4, fueron protegidos contra el desafio de formas infectantes. En una biblioteca de ADNc de epimastigotes de T. cruzi construída en el vector I gt11 se detectaron varios clones, tres con FCH-F8-4 y dos con FCH-F8-1. Dos clones, uno de cada grupo fueron estudiados, y (FCH-F8-1) 1 y (FCH-F8-4) 1. El tamaño de los insertos para ambos fue de 150 pares de bases y utilizados como sondas detectaron ARNm de epimastigotes de 3,5 y 5,0... (AU)

[Molecular and immunologic bases for the development of a vaccine against Chagas disease]. / Bases moleculares e inmunológicas para el desarrollo de una vacuna contra la enfermedad de Chagas.

Subcellular fractions of T. cruzi epimastigotes (Epi) were studied for their capability to induce protective or aggressive effects in animals. The flagellar fraction (F) showed the best immunoprotective properties without tissular aggression. Monoclonal antibodies were raised against F. Two of them, FCH-F8-1 and 4, were able to neutralize the infectivity of bloodstream forms, to mediate lysis by complement of cell culture derived[trypomastigotes (Tripo) and to recognize the surface of Tripo and Epi. FCH-F8-1 reacted with a 85 kDa protein from Tripo (assayed by immunoprecipitation) and with peptides of 43 kDa on Epi and Tripo (tested by immunoblotting). FCH-F8-4 recognized several proteins ranging from 50 to 150 kDa on Epi and two molecules of 15 and 48 kDa on Tripo. Mice immunized with antigens purified by affinity chromatography by using FCH-F8-4 were protected against the infection. Several recombinant clones were detected on a cDNA lambda gt11 expression library constructed from T. cruzi Epi (Tulahuén strain): three with FCH-F8-4 and two with FCH-F8-1. One clone recognized by each monoclonal antibody was studied gamma (FCH-F8-1) 1 and gamma (FCH-F8-4) 1. Both inserts were of 150 base pairs each; they detected a 3.5 and 5.0 kilobases Epi mRNA, respectively. Both inserts were sequenced, and the amino acid sequences were inferred. gamma (FCH-F8-4) 1 codified for a 19 aa peptide, PAFLGCSSRFSGSFSGVEP, and gamma (FCH-F8-1) 1 for a 29 aa peptide EFLERGRISCORHSYTSYTSCSDEHNVTPFC. The whole 19 aa peptide was synthesized. This peptide (SP4) inhibited the ELISA reactivity against the parasite of chronically infected and F immunized mouse sera.(ABSTRACT TRUNCATED AT 250 WORDS)

Bases moleculares e inmunológicas para el desarrollo de una vacuna contra la enfermedad de Chagas. / [Molecular and immunologic bases for the development of a vaccine against Chagas disease]

Subcellular fractions of T. cruzi epimastigotes (Epi) were studied for their capability to induce protective or aggressive effects in animals. The flagellar fraction (F) showed the best immunoprotective properties without tissular aggression. Monoclonal antibodies were raised against F. Two of them, FCH-F8-1 and 4, were able to neutralize the infectivity of bloodstream forms, to mediate lysis by complement of cell culture derived[trypomastigotes (Tripo) and to recognize the surface of Tripo and Epi. FCH-F8-1 reacted with a 85 kDa protein from Tripo (assayed by immunoprecipitation) and with peptides of 43 kDa on Epi and Tripo (tested by immunoblotting). FCH-F8-4 recognized several proteins ranging from 50 to 150 kDa on Epi and two molecules of 15 and 48 kDa on Tripo. Mice immunized with antigens purified by affinity chromatography by using FCH-F8-4 were protected against the infection. Several recombinant clones were detected on a cDNA lambda gt11 expression library constructed from T. cruzi Epi (Tulahuén strain): three with FCH-F8-4 and two with FCH-F8-1. One clone recognized by each monoclonal antibody was studied gamma (FCH-F8-1) 1 and gamma (FCH-F8-4) 1. Both inserts were of 150 base pairs each; they detected a 3.5 and 5.0 kilobases Epi mRNA, respectively. Both inserts were sequenced, and the amino acid sequences were inferred. gamma (FCH-F8-4) 1 codified for a 19 aa peptide, PAFLGCSSRFSGSFSGVEP, and gamma (FCH-F8-1) 1 for a 29 aa peptide EFLERGRISCORHSYTSYTSCSDEHNVTPFC. The whole 19 aa peptide was synthesized. This peptide (SP4) inhibited the ELISA reactivity against the parasite of chronically infected and F immunized mouse sera.(ABSTRACT TRUNCATED AT 250 WORDS)