Oxidative stress in blood of camels (Camelus dromedaries) naturally infected with Trypanosoma evansi

The phosphoarginine energy-buffering system of trypanosoma brucei involves multiple arginine kinase isoforms with different subcellular locations

Phosphagen energy-buffering systems play an essential role in regulating the cellular energy homeostasis in periods of high-energy demand or energy supply fluctuations. Here we describe the phosphoarginine/arginine kinase system of the kinetoplastid parasite Trypanosoma brucei, consisting of three highly similar arginine kinase isoforms (TbAK1-3). Immunofluorescence microscopy using myc-tagged protein versions revealed that each isoform is located in a specific subcellular compartment: TbAK1 is exclusively found in the flagellum, TbAK2 in the glycosome, and TbAK3 in the cytosol of T. brucei. The flagellar location of TbAK1 is dependent on a 22 amino acid long N-terminal sequence, which is sufficient for targeting a GFP-fusion protein to the trypanosome flagellum. The glycosomal location of TbAK2 is in agreement with the presence of a conserved peroxisomal targeting signal, the C-terminal tripeptide ‘SNL’. TbAK3 lacks any apparent targeting sequences and is accordingly located in the cytosol of the parasite. Northern blot analysis indicated that each TbAK isoform is differentially expressed in bloodstream and procyclic forms of T. brucei, while the total cellular arginine kinase activity was 3-fold higher in bloodstream form trypanosomes. These results suggest a substantial change in the temporal and spatial energy requirements during parasite differentiation. Increased arginine kinase activity improved growth of procyclic form T. brucei during oxidative challenges with hydrogen peroxide. Elimination of the total cellular arginine kinase activity by RNA interference significantly decreased growth (>90%) of procyclic form T. brucei under standard culture conditions and was lethal for this life cycle stage in the presence of hydrogen peroxide. The putative physiological roles of the different TbAK isoforms in T. brucei are further discussed.

Nitric oxide level, protein oxidation and antioxidant enzymes in rats infected by Trypanosoma evansi

The aim of this study was to evaluate the nitric oxide (NO()) level, protein oxidation and antioxidant enzymes in rats infected with Trypanosoma evansi and establish the association of NO() levels with the degree of parasitemia. Thirty-six male rats (Wistar) were divided into two groups with 18 animals each. Group A was not infected while Group B was intraperitoneally infected, receiving 7.5×10(6) trypomastigotes per animal. Each group was divided into three subgroups with 6 rats each and blood was collected during different periods post-infection (PI), as follows: day 5 (A(5) and B(5)), day 15 (A(15) and B(15)) and day 30 PI (A(30) and B(30)). Blood samples were collected by cardiac puncture to estimate the levels of nitrites/nitrates (NO(x)) and advanced oxidation protein products (AOPP) in serum, and superoxide dismutase (SOD) and catalase (CAT) activities in blood. On days 15 and 30 PI NO(x) and AOPP levels were increased in serum of rats infected. Rodents infected with T. evansi showed a significant increase in SOD (days 5 and 15 PI) and CAT (day 30 PI) activities. Based on the physiological role of NO(), we can conclude that its increased concentration is related to an inflammatory response against the parasite, once a redox imbalance was observed during infection.

Pathogenic mechanisms of Trypanosoma evansi infections

Insect-borne diseases exact a high public health burden and have a devastating impact on livestock and agriculture. To date, control has proved to be exceedingly difficult. One such disease that has plagued sub-Saharan Africa is caused by the protozoan African trypanosomes (Trypanosoma species) and transmitted by tsetse flies (Diptera: Glossinidae). This presentation describes Trypanosoma evansi (T. evansi) which causes the disease known as trypanosomosis (Surra) or trypanosomiasis in which several attempts have being made to unravel the clinical pathogenic mechanisms in T. evansi infections, yielding various reports which have implicated hemolysis associated to decrease in life span of erythrocytes and extensive erythrophagocytosis being among those that enjoy prominence. T. evansi generates Adenosine Triphosphate (ATP) from glucose catabolism which is required for the parasite motility and survival. Oxidation of the erythrocytes induces oxidative stress due to free radical generation. Lipid peroxidation of the erythrocytes causes membrane injury, osmotic fragility and destruction of the red blood cell (RBC) making anemia a hallmark of the pathology of T. evansi infections.

Trypanocidal potentials of Azadirachta indica seeds against Trypanosoma evansi

The trypanocidal potentials of Azadirachta indica seeds methanolic extract (NSME) against Trypanosoma evansi was examined. In vitro studies with the NSME 100mg/ml, 50mg/ml and 25mg/ml immobilized the parasites within 3 min, 8 min and 14 min respectively. In vivo experiments in infected rats at various dosage with NSME expressed transient ability of clearing the parasites in the infected blood. Thin layer chromatographic (TLC) separations of the NSME gave 4 fractions in toluene and ethyl acetate [1:0.25] solvent system on TLC of which only fraction 3 (F3) retained the trypanocidal properties which cleared the parasites in the infected rats for 14 days. The high performance liquid chromatography (HPLC) analysis of NSF F3 revealed the presence of Azadirachtins A and B as active components. The NSF F3 manifested prophylactic potency at a dose of 500 mg/kg/day × 3/7. The packed cell volume (PCV) of the group administered 500 mg/kg/day × 3/7 NSF F3 and normal control (NC) had no significant difference. The NSF F3 also inhibited Phospholipase A(2) enzyme in a dose-dependent pattern.

Antioxidant enzymes in erythrocytes from goats seropositive to the sheep nose bot fly (Oestrus ovis L., Diptera: Oestridae) infection

Oestrus ovis (Diptera: Oestridae) causes an important cosmopolitan parasitosis of the nasal and sinusal cavities of sheep and goats called oestrosis. Our objective was to analyze the participation of erythrocytes in the antioxidant system in goats seropositive to O. ovis infection under field conditions. Fifty female goats naturally exposed to O. ovis infection from Baja California Sur, México, were blood-sampled. Erythrocytic intracellular content was obtained from blood plasma. Oestrosis serodiagnosis was determined by ELISA. Protein, hemoglobin (Hb), superoxide dismutase (SOD), mieloperoxidase (MPO), catalase (CAT), glutathione-S-transferase (GST), and lipid peroxidation in erythrocytes were determined in both seropositive and seronegative goats. Overall seroprevalence of O. ovis infection in goats was 56%. Positive significant (P<0.05) associations were observed among systemic IgG level and protein (0.34), hemoglobin (0.43), SOD (0.32), and MPO (0.41) in erythrocytes. Protein and hemoglobin concentrations, as well as SOD and MPO activities in erythrocytes were found significantly higher (P<0.05) in seropositive than in seronegative goats. By contrast, enzymatic activities of CAT and GST and lipid peroxidation values were similar in seropositive and seronegative groups. In conclusion, there was a systemic stimulation of Reactive Oxygen Species which was efficiently scavenged by erythrocytic antioxidant enzymes in goats seropositive to O. ovis infection.

Trypanosoma evansi: Ca(2+) ATPase activity and lipid peroxidation in skeletal muscle from rats experimentally infected

The aim of this study was to evaluate Ca(2+) ATPase activity and the lipid peroxidation in muscles from rats experimentally infected by Trypanosoma evansi and its roles in the muscle pathogenesis in trypanosomosis. Thirty-six rats were divided in two groups. Group A was infected with an isolate from T. evansi and group B was used as a negative control. Group A was divided into three subgroups (A1, A2 and A3), three animals each group, as well as group B (B1, B2 and B3). The collection of samples were performed at days 5 (A1 and B1), 15 (A2 and B2) and 30 (A3 and B3) post-infection (PI) with the purpose of comparison between healthy and infected rats in the course of the disease. The Ca(2+) ATPase enzyme activity was determined in skeletal muscle samples. Muscle tissue lipid peroxidation was determined by TBARS levels, and histopathologically it was investigated a possible damage to the muscle tissue of rats infected with T. evansi. It was observed a significant decrease of Ca(2+) ATPase activity in infected rats compared to not-infected. This enzymatic inhibition was observed at days 5, 15 and 30 PI. A significant increase was observed for TBARS levels in the muscles of infected rats at days 5, 15 and 30 PI. It was not identified any histological alterations for gastrocnemius in rats infected by T. evansi at days 5 and 15 PI. Nevertheless, at day 30 PI it was verified inflammatory infiltrate with mononuclear cells between muscle fibers in three infected rats (50%). T. evansi infections in rats showed a negative correlation between Ca(2+) ATPase and TBARS levels. Based on these results we suggest that the leg weakness and muscle injuries common in infected animals with T. evansi may be related to a reduced activity of Ca(2+) ATPase and oxidative stress.

Disturbance of oxidant/antioxidant equilibrium in horses naturally infected with Trypanosoma evansi

Oxidant/antioxidant equilibrium disturbance has already been reported in trypanosome infections by several authors. The present study was aimed to explore the possible oxidant/antioxidant disturbance in surra of naturally infected horses before and after treatment. Fifteen naturally infected horses were chosen to analyse erythrocytic indices, platelet counts, lipid peroxides (LPO), nitric oxide (NO), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) while six healthy animals acted as control. There was a highly significant (P<0.001) reduction in red blood cell (RBC) count, haemoglobin (Hb), packed cell volume (PCV) and platelet levels and a significant reduction in mean corpuscular haemoglobin concentration (MCHC) (P<0.05) was noticed. A highly significant increase in NO (P<0.001), a significant increase in LPO (P<0.05) and a significant decrease in GSH, SOD and CAT (P<0.05) were found. A negative correlation of RBC count with LPO (r=-0.844) and nitrate (r=-0.702) while a positive correlation with GSH (r=0.489), SOD (r=0.580) and CAT (r=0.689) was observed. All the animals were treated with Quinapyramine sulphate (3mg/kg s.c.) only once. Nine animals recovered completely without any side effects. The recovered animals were monitored and samples were collected every seven days for up to 21 days and parameters were analysed. After treatment, a significant increase in haematological parameters was noticed whereas the oxidative indices varied without any statistical significance. To conclude, the increase in oxidant parameters and decrease in antioxidant enzymes in infected horses indicates the disturbance of oxidant/antioxidant indices. There was a significant increase in post therapy haematological values, while the oxidant/antioxidant indices changed insignificantly indicating that antioxidants might be supplemented in the therapeutic regimen.

Sequencing, analysis, and annotation of expressed sequence tags for Camelus dromedarius

Despite its economical, cultural, and biological importance, there has not been a large scale sequencing project to date for Camelus dromedarius. With the goal of sequencing complete DNA of the organism, we first established and sequenced camel EST libraries, generating 70,272 reads. Following trimming, chimera check, repeat masking, cluster and assembly, we obtained 23,602 putative gene sequences, out of which over 4,500 potentially novel or fast evolving gene sequences do not carry any homology to other available genomes. Functional annotation of sequences with similarities in nucleotide and protein databases has been obtained using Gene Ontology classification. Comparison to available full length cDNA sequences and Open Reading Frame (ORF) analysis of camel sequences that exhibit homology to known genes show more than 80% of the contigs with an ORF>300 bp and ∼40% hits extending to the start codons of full length cDNAs suggesting successful characterization of camel genes. Similarity analyses are done separately for different organisms including human, mouse, bovine, and rat. Accompanying web portal, CAGBASE (http://camel.kacst.edu.sa/), hosts a relational database containing annotated EST sequences and analysis tools with possibility to add sequences from public domain. We anticipate our results to provide a home base for genomic studies of camel and other comparative studies enabling a starting point for whole genome sequencing of the organism.

Evaluation of In Vitro Activity of Essential Oils against Trypanosoma brucei brucei and Trypanosoma evansi

Essential oils (EOs) from Cymbopogon citratus (CC), Eucalyptus citriodora (EC), Eucalyptus camaldulensis (ED), and Citrus sinensis (CS) were obtained by hydrodistillation process. The EOs were evaluated in vitro for activity against Trypanosoma brucei brucei (Tbb) and Trypanosoma evansi (T. evansi). The EOs were found to possess antitrypanosomal activity in vitro in a dose-dependent pattern in a short period of time. The drop in number of parasite over time was achieved doses of 0.4 g/ml, 0.2 g/mL, and 0.1 g/mL for all the EOs. The concentration of 0.4 g/mL CC was more potent at 3 minutes and 2 minutes for Tbb and T. evansi, respectively. The GC-MS analysis of the EOs revealed presence of Cyclobutane (96.09%) in CS, 6-octenal (77.11%) in EC, Eucalyptol (75%) in ED, and Citral (38.32%) in CC among several other organic compounds. The results are discussed in relation to trypanosome chemotherapy.

Trypanosoma evansi: Effect of experimental infection on the osmotic fragility, lipid peroxidation and calcium-ATPase activity of rat red blood cells

Trypanosoma evansi is the causative agent of equine trypanosomoses. The disease is characterized by fever, anemia, and cachexia. Peroxidative damage of the red blood cells caused by the parasite, may contribute to the pathogenesis of the anemia seen in trypanosomoses. Consequently, we evaluated the hematocrit, the osmotic fragility of the red blood cells, the level of lipid peroxidation and the activity of the Ca-ATPase of red blood cell ghosts from rats experimentally infected with T. evansi. After 72 h inoculation, the hematocrit decreased from 49.5% to 33%; the osmotic fragility of the red blood cells was approximately 40% higher as compared to the healthy animals; and the red blood cell ghosts showed a higher level of lipid peroxidation and a lower Ca-ATPase activity than the red cell ghosts from the healthy animals. In vitro incubations of red blood cells from healthy animals with T. evansi, produced also a significant increase of the osmotic fragility of the red blood cells.