Looking for combination of benznidazole and Trypanosoma cruzi-triosephosphate isomerase inhibitors for Chagas disease treatment

BACKGROUND The current chemotherapy for Chagas disease is based on monopharmacology with low efficacy and drug tolerance. Polypharmacology is one of the strategies to overcome these limitations. OBJECTIVES Study the anti-Trypanosoma cruzi activity of associations of benznidazole (Bnz) with three new synthetic T. cruzi-triosephosphate isomerase inhibitors, 2, 3, and 4, in order to potentiate their actions. METHODS The in vitro effect of the drug combinations were determined constructing the corresponding isobolograms. In vivo activities were assessed using an acute murine model of Chagas disease evaluating parasitaemias, mortalities and IgG anti-T. cruzi antibodies. FINDINGS The effect of Bnz combined with each of these compounds, on the growth of epimastigotes, indicated an additive action or a synergic action, when combining it with 2 or 3, respectively, and an antagonic action when combining it with 4. In vivo studies, for the two chosen combinations, 2 or 3 plus one fifth equivalent of Bnz, showed that Bnz can also potentiate the in vivo therapeutic effects. For both combinations a decrease in the number of trypomastigote and lower levels of anti-T. cruzi IgG-antibodies were detected, as well clear protection against death. MAIN CONCLUSIONS These results suggest the studied combinations could be used in the treatment of Chagas disease.

Differential Protein Expressions in Virus-Infected and Uninfected Trichomonas vaginalis

Protozoan viruses may influence the function and pathogenicity of the protozoa. Trichomonas vaginalis is a parasitic protozoan that could contain a double stranded RNA (dsRNA) virus, T. vaginalis virus (TVV). However, there are few reports on the properties of the virus. To further determine variations in protein expression of T. vaginalis, we detected 2 strains of T. vaginalis; the virus-infected (V⁺) and uninfected (V⁻) isolates to examine differentially expressed proteins upon TVV infection. Using a stable isotope N-terminal labeling strategy (iTRAQ) on soluble fractions to analyze proteomes, we identified 293 proteins, of which 50 were altered in V⁺ compared with V⁻ isolates. The results showed that the expression of 29 proteins was increased, and 21 proteins decreased in V⁺ isolates. These differentially expressed proteins can be classified into 4 categories: ribosomal proteins, metabolic enzymes, heat shock proteins, and putative uncharacterized proteins. Quantitative PCR was used to detect 4 metabolic processes proteins: glycogen phosphorylase, malate dehydrogenase, triosephosphate isomerase, and glucose-6-phosphate isomerase, which were differentially expressed in V⁺ and V⁻ isolates. Our findings suggest that mRNA levels of these genes were consistent with protein expression levels. This study was the first which analyzed protein expression variations upon TVV infection. These observations will provide a basis for future studies concerning the possible roles of these proteins in host-parasite interactions.

Multiplex Real-Time PCR Method for Simultaneous Identification and Toxigenic Type Characterization of Clostridium difficile From Stool Samples

BACKGROUND: The aim of this study was to develop and validate a multiplex real-time PCR assay for simultaneous identification and toxigenic type characterization of Clostridium difficile. METHODS: The multiplex real-time PCR assay targeted and simultaneously detected triose phosphate isomerase (tpi) and binary toxin (cdtA) genes, and toxin A (tcdA) and B (tcdB) genes in the first and sec tubes, respectively. The results of multiplex real-time PCR were compared to those of the BD GeneOhm Cdiff assay, targeting the tcdB gene alone. The toxigenic culture was used as the reference, where toxin genes were detected by multiplex real-time PCR. RESULTS: A total of 351 stool samples from consecutive patients were included in the study. Fifty-five stool samples (15.6%) were determined to be positive for the presence of C. difficile by using multiplex real-time PCR. Of these, 48 (87.2%) were toxigenic (46 tcdA and tcdB-positive, two positive for only tcdB) and 11 (22.9%) were cdtA-positive. The sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of the multiplex real-time PCR compared with the toxigenic culture were 95.6%, 98.6%, 91.6%, and 99.3%, respectively. The analytical sensitivity of the multiplex real-time PCR assay was determined to be 103colonyforming unit (CFU)/g spiked stool sample and 0.0625 pg genomic DNA from culture. Analytical specificity determined by using 15 enteric and non-clostridial reference strains was 100%. CONCLUSIONS: The multiplex real-time PCR assay accurately detected C. difficile isolates from diarrheal stool samples and characterized its toxin genes in a single PCR run.

Comparison of ChromID Agar and Clostridium difficile Selective Agar for Effective Isolation of C. difficile from Stool Specimens

BACKGROUND: ChromID Clostridium difficile agar (IDCd; bioMerieux SA, France) is a recently developed chromogenic medium for rapid and specific isolation of C. difficile. We compared the performance of IDCd with that of Clostridium difficile Selective Agar (CDSA). METHODS: A total of 530 fresh stool specimens were collected from patients with clinical signs compatible with C. difficile infection, and cultures for C. difficile were performed on IDCd and CDSA. C. difficile colonies were identified by spore staining, odor, use of an ANI identification test kit (bioMerieux SA), and multiplex PCR for tcdA, tcdB, and tpi. RESULTS: The concordance rate between IDCd and CDSA was 90.6% (480/530). The positivity rates on IDCd on days 1 and 2 (55.6% and 85.0%, respectively) were significantly higher than those on CDSA (19.4% and 75.6%, respectively) (P<0.001 for day 1 and P=0.02 for day 2), but the detection rates on IDCd and CDSA on day 3 were not different (89.4% vs. 82.8%, P=0.0914). On day 3, the recovery rates for non-C. difficile isolates on IDCd and CDSA were 30.2% (160/530) and 22.1% (117/530), respectively (P=0.0075). Clostridium spp. other than C. difficile were the most prevalent non-C. difficile isolates on both media. CONCLUSIONS: The culture positivity rates on IDCd and CDSA were not different on day 3 but IDCd may allow for rapid and sensitive detection of C. difficile within 2 days of cultivation.

Genotyping of Giardia duodenalis Isolates from Dogs in Guangdong, China Based on Multi-Locus Sequence

This study aimed to identify the assemblages (or subassemblages) of Giardia duodenalis by using normal or nested PCR based on 4 genetic loci: glutamate dehydrogenase (gdh), triose phosphate isomerase (tpi), beta-giardin (bg), and small subunit ribosomal DNA (18S rRNA) genes. For this work, a total of 216 dogs' fecal samples were collected in Guangdong, China. The phylogenetic trees were constructed with MEGA5.2 by using the neighbor-joining method. Results showed that 9.7% (21/216) samples were found to be positive; moreover, 10 samples were single infection (7 isolates assemblage A, 2 isolates assemblage C, and 1 isolate assemblage D) and 11 samples were mixed infections where assemblage A was predominant, which was potentially zoonotic. These findings showed that most of the dogs in Guangdong were infected or mixed-infected with assemblage A, and multi-locus sequence typing could be the best selection for the genotype analysis of dog-derived Giardia isolates.

First genotyping of Giardia lamblia from human and animal feces in Argentina, South America

The purpose of this study was to investigate the genotypes of Giardia lamblia from human and animal feces and their epidemiological and clinical characteristics in Argentina, South America. Seventy isolates, 60 from humans (adults and children), eight from dogs and two from cows were processed by polymerase chain reaction-restriction fragment length polymorphism. Data corresponding to demographic, socio-cultural and environmental variables and presence/absence of signs/symptoms were collected. The triosephosphate isomerase gene was amplified from 43 (71.66 percent) of the 60 human fecal samples. Among these, 3/43 (6.98 percent) were genotype AII and 40/43 (93.02 percent) were genotype B. Assemblage AII was detected in three children who lived together in a shantytown and they were oligosymptomatic and none had diarrhea. This genotype was not found in animals. Genotype B showed a high prevalence in both adults and children. It was also found in polysymptomatic people, many of whom presented diarrhea. It was also found only in one dog. The present study represents the first contribution to the knowledge of G. lamblia genotypes in Argentina.

The protective immunity of a DNA vaccine encoding Schistosoma japonicum Chinese strain triose-phosphate isomerase in infected BALB/C mice.

The development of a DNA vaccine for schistosomiasis japonica and testing the protective efficacy after challenge in BALB/c mice were performed. Thirty-nine female BALB/c mice were divided into three groups. Each mouse of the control group was injected intramuscularly with 100 microg of pcDNA3.1 DNA. In the TPI group, each mouse was injected with 100 microg of pcDNA3.1-SjCTPI DNA. The TPI+IL-12 group was injected with 100 microg of pcDNA3.1-SjCTPI DNA and 100 microg of the mixture of pcDNA3.1-P35 and pcDNA3.1-P40 DNA. Each mouse was immunized three times at two-week intervals and challenged with 45 cercariae of Schistosoma japonicum Chinese strain four weeks post-immunization. Then the mice were sacrificed and perfused at 45 days after challenge; the recovered worms and hepatic eggs were counted. Cytotoxic T lymphocyte (CTL) activity mediated by SjCTPI was detected with the 51Cr release assay. ELISA was performed for the detection of anti-rTPI antibodies. Anti-rTPI antibody detection with ELISA after immunization showed ten serum samples from the control group were negative, five of ten serum samples from the TPI group were weakly positive, six of ten from the TPI+IL-12 group were also weakly positive. The CTL activity of the control group was 9.1%, while CTL activities of the TPI group and the TPI+IL-12 group were 27.6% and 54.4%, respectively. The worm and egg reduction rates of TPI group and the TPI+IL-12 group were 30.2%, 52.9%, 32.7%, and 47.0%, respectively in comparison with the control group. This study further proved the possibility of the SjCTPI DNA vaccine as a potential DNA vaccine for schistosomiasis.

The protective immunity produced in infected C57BL/6 mice of a DNA vaccine encoding Schistosoma japonicum Chinese strain triose-phosphate isomerase.

The development of a SjCTPI DNA vaccine for Schistosoma japonicum and the detection of the immune responses to and the protective efficacy of immunization were performed and challenged in C57BL/6 mice. According to the gene sequence of SjCTPI and murine IL-12, three pairs of primers were designed. The full length cDNA encoding SjCTPI and P35, P40 amplified from pUC19-SjCTPI and murine IL-12 by PCR were subcloned into an eukaryotic expression vector (pcDNA3.1). Forty-five female C57BL/6 mice were divided into three groups; each mouse of the control group was injected with 100 pg of pcDNA3.1 by i.m. route; the TPI group was injected with 100 microg of pcDNA3. 1-SjCTPI; the TPI+IL- 12 group was injected with 100 microg of pcDNA3.1-SjCTPI and 100 pg of mixture of pcDNA3.1-P35 and pcDNA3.1-P40. Each mouse was immunized at weeks 1 and 5 and challenged with 45 cercariae of Schistosoma japonicum Chinese strain at week 9. The mice were killed and perfused 45 days after challenge; the numbers of recovered worms and hepatic eggs were counted. The expression of SjCTPI in muscle tissue was determined by an immunohistochemical method. Culture of spleen cells showed the production of IL-2, IL-4, IL-10 and IFN-gamma with the stimulation of specific antigen before and after challenge. Sera were collected from each group before immunization, before challenge and two weeks post challenge; ELISA and Western-blot tests were performed for detection of anti-rTPI antibodies. The antigen of SjCTPI was expressed in the membrane and plasma of the muscle cells of C57BL/6 mice. The obvious rising of IL-2 in TPI group and TPI+IL-12 group before and after challenge was seen. The anti-rTPI antibody detection with Western-blot showed that ten serum samples from the control group were negative; nine of ten serum samples from the TPI group were weakly positive, eight of ten from the TPI+IL-12 group were weakly positive. The worm and egg reduction rates of TPI group and TPI+IL- 12 group were 27.9% and 13.7%, 31.9% and 18.6% respectively in comparison with the pcDNA group. pcDNA3.1-TPI DNA vaccine could confer partial protection against a subsequent challenge of Schistosoma japonicum in C57BL/6 mice and might therefore be a potential DNA vaccine.

The intraspecific difference of the triose phosphate isomerase (tim) gene from Giardia lamblia / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To investigate the intraspecific difference of the triose phosphate isomerase (tim) gene from Giardia lamblia (G. lamblia).</p><p><b>METHODS</b>Total genomic DNA of G. lamblia was extracted and partial fragments of the triose phosphate isomerase (tim) gene were amplified by polymerase chain reaction (PCR). All nucleotide sequences were analyzed by using a phylogenetic analysis, which was constructed with parsimony and Neighbor-joining (N-J) methods.</p><p><b>RESULTS</b>A total of 124 variable sites (23% of all sequences detected) was defined, most of which were found at the silent sites of codons. Two similar phylogenetic trees were constructed, subdividing 16 Giardia isolates into two groups.</p><p><b>CONCLUSION</b>The genetic diversity of G. lamblia appeared to be little affected by factors of both host and geography, while natural-selection played an important role in DNA molecular evolution level of the tim gene. The tim gene may be considered a very useful genetic marker of the population genetic structure of G. lamblia.</p>

DNA sequence analysis of the triose phosphate isomerase gene from isolates of Giardia lamblia / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To confirm the genetic relation between Giardia lamblia (G. lamblia) isolates from different geographic regions of China and other countries.</p><p><b>METHODS</b>Genomic DNA were extracted from the trophozoites or cysts of Giardia lamblia. The triose phosphate isomerase (tim) gene was amplified using polymerase chain reaction (PCR) technique. PCR products were digested with endonuclease and sequenced. The data of sequencing were analyzed with the DNAstar software and compared with that of the isolates acquired from GenBank.</p><p><b>RESULTS</b>Of nine isolates of Giardia lamblia from China (C1, C2, CH2 and CH3), Cambodia (CAM), Australia (A1 and A2) and America (BP and CDC), respectively, 3 (A1, A2 and CAM) fit into Group 1 (WB), 2 (CH2 and CH3)) into Group 2, and 4 (C1, C2, BP and CDC) into Group 3 (GS). The results confirmed the genetic relatedness of G. lamblia isolates from all over the world.</p><p><b>CONCLUSION</b>Genotyping isolates of G. Lamblia provides important information for establishing the phylogenetic relationship or for the epidemiological evaluation of the spreading of this organism.</p>

Gene cloning and amino acid sequence analysis of triose-phosphate isomerase of Schistosoma japonicum Chinese strain.

A pair of primers was synthesized according to the DNA sequence of Schistosoma japonicum Philippine strain, and the mRNA of adult worms of S. japonicum Chinese strain was prepared. The gene of triose-phosphate isomerase of S. japonicum Chinese strain (SjC TPI) was successfully cloned from the mRNA through reverse transcription polymerase chain reaction (RT-PCR) technic with the primers. The DNA sequence of the gene showed that the open reading frame of encoding SjC TPI DNA includes 759bp, which has 84% homology to Sm TPI, 99.7% homology to SjP TPI. The analysis of deduced amino acid sequence of SjC TPI indicates that SjC TPI is 84.9% (214/252) identical with Sm TPI and 99.2% (250/252) with SjP TPI. The peptide-structure analysis presents 7 extra-surface, hydrophilic regions in the molecule of SjC TPI, the molecular weight of SjC TPI is 27,619. The isoelectric point is 7.38.

Purification and partial characterization of Trypanosoma cruzi triosephosphate isomerase

The enzyme triosephosphate isomerase (TPI, EC 5.3.1.1) was purified from extracts of epimastigote forms of Trypanosoma cruzi. The purification steps included: hydrophobic interaction chromatography on plenyl-Sepharose, CM-Sepharose, and high performance liquid gel filtration chromatography. The CM-Sepharose material contained two bands (27 and 25 kDa) with similar isolectric points (pI 9.3-9.5) which could be separated by gel filtration in high performance liquid chromatography. Polyclonal antibodies raised against the porcine TPI detected one single polypeptide on western blot with a molecular weight (27 kDa) identical to that purified from T. cruzi. These antibodies also recognized only one band of identical molecular weight in western blots of several other trypanosomatids (Blastocrithidia culicis, Crithidia desouzai, Phytomonas serpens, Herpertomonas samuelpessoai). The presence of only one enzymatic form of TPI in T. cruzi epimastigotes was confirmed by agarose gel activity assay and its localization was established by immunocytichemical analysis. The T. cruzi purified TPI (as well as other trypanosomatid' TPIs) is a dimeric protein, composed of two identical subunits with an approximate mw of 27,000 and it is resolved on two dimensional gel electrophoresis with a pI of 9.3. Sequence analysis of the N-terminal portion of the 27 kDa protein revealed a high homology to Leishmania mexicana and T. brucei proteins.

Gel chromatographic experiments for studying subunit interaction of aldolase and triose-phosphate isomerase

Aldolase and triose-phosphate isomerase [TPI] were prepared and purified from rabbit skeletal muscle by gel chromatographic methods. Molecular weight determination and subunit interaction were demonstrated by gel filtration experiments. Cross-linking of aldolase subunit and TPI subunit with glutaraldehyde was detected from the elution profile of sephadex G/200 column which equilibrated with known proteins. Chemical interaction of the lysyl residue of aldolase with different inhibitors such as acetyl chloride, benzoyl chloride, chloroacetic acid, acetic anhydride, thiourea, thioacetamide and bromo ethyl acetate can prevent the Schiff's base formation and may induce some conformational changes. These conformational changes near catalytic site of aldolase causing inhibition of its catalytic function

Caracterizaçäo do gene da triose fosfato isomerase do schistosoma mansoni / Characterization of the gene ensyme triose phosphate isomerase of schistosoma mansoni

O gene completo codificando a enzima triose fosfato isomerase (TPI) do Schistosoma mansoni foi caracterizado a partir do estudo de dois ciclones exibindo áreas de superposiçäo, isolados, de uma biblioteca genômica em fago de lambda. Estes clones genômicos foram caracterizados através de mapas de restriçäo, sequenciamento do DNA envolvendo a regiäo a montante do gene ("5' flanking region"), exons, limites dos entrons e o sítio de poli-adenilaçäo. O gene da TPI do Schistosoma mansoni é codificado por 6 exons ocupando uma regiäo de aproximadamente 12 Kb. Os cinco introns estäo situados em posiçöes análogas aquelas para os genes da TPI de mamíferos, porém um dos 6 introns da TPI de mamíferos está ausente no S. mansoni. Nós näo encontramos evidências da participaçäo de "spliced leader" na expressäo do gene do TPI. O gene é precedido de pelo menos 4 cópias de sequências repetitivas de 2.5 Kb dispostas de forma linear. Apesar do gene de TPI de S. mansoni com 12 Kb, ser muito maior que um gene típico da TPI de um mamífero, o qual tem em média 3-4 Kb, ele apresenta o primeiro intron com apenas 42 bp. O sítio de iniciaçäo de transiçäo do S. mansoni é heterogêneo. A análise pela técnica de "Southern blot" sugere que o gene da TPI de S. mansoni se expressa a partir de uma única cópia do gene