Entamoeba histolytica is a causative agent of amoebic liver abscess (ALA) and is endemic in many underdeveloped countries. We investigated antigenic E. histolytica proteins in liver abscess aspirates using proteomics approach. Pus samples were first tested by real-time PCR to confirm the presence of E. histolytica DNA and the corresponding serum samples tested for E. histolytica-specific IgG by a commercial ELISA. Proteins were extracted from pus samples which were pooled from three and one patients with ALA and PLA (pyogenic liver abscess) respectively, followed by analysis using isoelectric focussing, SDS-PAGE and Western blot. Unpurified pooled serum samples from infected hamsters and pooled human amoebic-specific IgG were used as primary antibodies. The antigenic protein band was excised from the gel, digested and analysed by MALDI-TOF/TOF and LC-MS/MS. The results using both primary antibodies showed an antigenic protein band of ∼14 kDa. Based on the mass spectrum analysis, putative tyrosine kinase is the most probable identification of the antigenic band.

The therapeutic benefits of medicinal plants in terms of anthelmintic properties are known since time immemorial in India, particularly among natives of the Northeast India. However, only sporadic and scarce reports on scientific validation of these plants are available. The present study was conducted on the cestode Raillietina echinobothrida, to establish whether the anthelmintic activity of Potentilla fulgens, Alpinia nigra and Millettia pachycarpa was mediated by apoptosis or not. Light microscopic observation following MTT assay revealed the highest percentage of inhibition of viability among the worms by methanol extract of M. pachycarpa (89.33%), followed by A. nigra (65%) and P. fulgens (37%). Ultrastructural observations revealed swelling of mitochondria, disruption of mitochondrial membrane, vacuolization of mitochondria, appearance of apoptotic bodies in the cytoplasm, disintegration of nuclear membrane and nucleolus were very common throughout the tegument. DAPI stained specimens showed typical morphology of apoptosis, like nuclear condensation and fragmentation in the extracts treated parasites. A decrease in mitochondrial membrane potential was also recorded in the treated groups. Confirmatory TUNEL assay and DNA fragmentation assay of the extracts treated parasites also confirmed the apoptotic nature of cell death and is concluded to be responsible for paralysis and death of the parasite.

Neospora caninum is a protozoan that causes abortion in cattle and neuromuscular lesions in dogs, making it an important target of veterinary medicine. Lysosomes are cellular organelles responsible for important biological functions as cellular defense mechanisms. The aim of this work was to evaluate the lysosomal stability of rat gliocytes infected in vitro with N. caninum. Rat glial cultures were infected at a ratio of 1:1 (cell/parasite). The enzymatic activity of acid phosphatase (orthophosphoric-monoester phosphohydrolase, EC 3.1.3.2) was assayed in the medium of control and infected cell cultures. The activity observed at 24h of incubation was 0.4±0.08mU/mg/min for control cells and 1.3±0.5mU/mg/min for infected cells. After 72h, control and infected cells exhibited activities of 1.3±0.5 and 4.1±0.9mU/mg/min, respectively. These results suggested that lysosomal compartment plays an important role in the mechanisms of cellular infection by N. caninum.

Blocking transmission of malaria is a reliable way to control and eliminate infection. However, in-depth knowledge of the interaction between Plasmodium and mosquito is needed. Studies suggest that innate immunity is the main mechanism inhibiting development of malaria parasites in the mosquito. Recent studies have found that use of antibiotics that inhibit the mosquito gut flora can reduce the immune response of Anopheles gambiae, thereby contributing to the development of malaria parasites. In our study, we used the non susceptible model of Anopheles dirus-Plasmodium yoelii to explore the effect of Anopheles intestinal flora on the natural resistance of A. dirus to P. yoelii. We found that in mosquitoes infected with Plasmodium, the intestinal flora can regulate expression of thioester-containing protein (TEP1) via an RNAi gene-silencing approach. Our results suggest that in the absence of TEP1, the natural microbiota cannot suppress the development of P. yoelii in A. dirus. This suggests that AdTEP1 plays an important role in the resistance of A. dirus to P. yoelii. The intestinal flora may modulate the development of P. yoelii in A. dirus by regulating TEP1 expression.

Reduction in the parasitemic levels of the Y strain of Trypanosoma cruzi in mice treated with oral or intraperitoneal ursolic (UA) and oleanolic (OA) acids was evaluated during the acute phase of Chagas' disease. Oral administration of UA and OA (50mg/kg/day) provided the most significant reduction in the parasitemic peak, while intraperitoneal administration of UA and OA did not significantly affect the biological activity of the Y strain of T. cruzi. Interleukin levels in mice treated by the intraperitoneal route were compared to untreated chagasic mice. Reduced γ-IFN levels and enhanced IL-10 concentrations potentially explain the exacerbated parasitemia. Our data suggests an immunosuppressive effect for UA and OA, which could interfere with host control of parasitemia. Optimal results were achieved with oral administration. This observation may be explained by the low intestinal absorption of UA and OA, could cause a reduced immune response and promote parasite control. Taken together, these data demonstrate that triterpenes could be interesting compounds to develop therapeutically for the treatment of Chagas' disease.

We describe the course of infection of Cryptosporidium andersoni LI03, originally isolated from cattle, in outbred Gerbillus gerbillus (Lesser Egyptian Gerbil), Meriones unguiculatus (Mongolian gerbil), and Meriones tristrami (Tristram's jird). While both Meriones spp. partially cleared the infection and shed a low number of oocysts (less than 15,000 oocysts per gram (OPG)), chronic infection with a mean infection intensity reaching 200,000 OPG was observed in G. gerbillus. These data suggest that G. gerbillus can be used as a laboratory model for the long-term maintenance and study of C. andersoni without the need for host immunosuppression.

The monitoring of resistance of cattle tick populations in Brazil to the chemical bases in use is largely limited to investigation of the phenotypic profile. There are few studies investigating the role played by the genotypic profile in acaricide resistance in the country. Therefore, the aim of the present study was to carry out molecular characterization and trace out the genetic profile of populations of Rhipicephalus microplus with respect to resistance to the organophosphate and pyrethroid chemical groups. For that purpose, larvae were genotyped belonging to 587 populations for pyrethroids and 306 for organophosphates, using the polymerase chain reaction technique. It was found that 75.49% and 97.44% of the larvae studied showed resistance to the organophosphates and pyrethroids, respectively. Among the populations resistant to pyrethroids, 91.9% were heterozygotes, showing that most of the resistant populations have only one allele responsible for resistance. Therefore, it is possible to conclude that the genotyped populations have high resistance to organophosphates, and even more so to pyrethroids. This information is fundamental for understanding the mechanisms of resistance of R. microplus to acaricides, to enable improvement of control techniques.

In Trypanosoma cruzi gene expression regulation mainly relays on post-transcriptional events. Nevertheless, little is known about the signals which control mRNA abundance and functionality. We have previously found that CA repeated tracts (polyCA) are abundant in the vicinity of open reading frames and constitute specific targets for single stranded binding proteins from T. cruzi epimastigote. Given the reported examples of the involvement of polyCA motifs in gene expression regulation, we decided to further study their role in T. cruzi. Using an in silico genome-wide analysis, we identify the genes that contain polyCA within their predicted UTRs. We found that about 10% of T. cruzi genes carry polyCA therein. Strikingly, they are frequently concurrent with GT repeated tracts (polyGT), favoring the formation of a secondary structure exhibiting the complementary polydinucleotides in a double stranded helix. This feature is found in the species-specific family of genes coding for mucine associated proteins (MASPs) and other genes. For those polyCA-containing UTRs that lack polyGT, the polyCA is mainly predicted to adopt a single stranded structure. We further analyzed the functional role of such element using a reporter approach in T. cruzi. We found out that the insertion of polyCA at the 3' UTR of a reporter gene in the pTEX vector modulates its expression along the parasite's life cycle. While no significant change of the mRNA steady state of the reporter gene could be detected at the trypomastigote stage, significant increase in the epimastigote and reduction in the amastigote stage were observed. Altogether, these results suggest the involvement of polyCA as a signal in gene expression regulation in T. cruzi.

In the present study, the poly(lactide-co-glycolide) (PLG) polymer was used as an adjuvant to encapsulate the chimeric protein rSAG1/2 for preparing a microparticle vaccine against Toxoplasma gondii. The resulting PLG-encapsulated rSAG1/2 (PLG-rSAG1/2) microparticles, 1.27-1.65μm in diameter, showed 72-83% entrapment efficiency. The amount of released rSAG1/2 protein from microparticles gradually increased over a long 56-day period and the protein still retained its antigenicity. Intraperitoneal immunization with the microparticles in BALB/c mice elicited significant long-term (10weeks) humoral and cell-mediated immune responses, accompanied by secretion of a large amount of IFN-γ, to achieve strong protection (83%) against a lethal subcutaneous tachyzoite challenge. In conclusion, we have successfully encapsulated rSAG1/2 with the PLG polymer to produce stable microparticles that can effectively induce not only long-term immunity but also high protection against T. gondii. These crucial data would be advantageous for developing long-term Toxoplasma vaccines for future use in humans and animals.

Currently, the most efficient and widely used method for tick control is the application of acaricides, especially deltamethrin and alpha-cypermethrin, two pyrethroids with neurotoxic action. In this study, the in vitro efficacy of deltamethrin and alpha-cypermethrin was assessed on engorged female Haemaphysalis qinghaiensis ticks. An in vitro bioassay (adult immersion test) was carried out to determine the LC (lethal concentration) 50 and LC90 of both compounds, calculated by probit analysis. The LC50 and LC90 values of deltamethrin and alpha-cypermethrin were 5.67 (LC50) and 51.72ppm (LC90), and 166.56 (LC50) and 1366.69ppm (LC90), respectively. This study provides important information on the efficacy of deltamethrin and alpha-cypermethrin for the control of H. qinghaiensis.