A rhamnose-binding lectin from Rhodnius prolixus and the impact of its silencing on gut bacterial microbiota and Trypanosoma cruzi.

Lectins are ubiquitous proteins involved in the immune defenses of different organisms and mainly responsible for non-self-recognition and agglutination reactions. This work describes molecular and biological characterization of a rhamnose-binding lectin (RBL) from Rhodnius prolixus, which possesses a 21 amino acid signal peptide and a mature protein of 34.6 kDa. The in-silico analysis of the primary and secondary structures of RpLec revealed a lectin domain fully conserved among previous insects studied. The three-dimensional homology model of RpLec was similar to other RBL-lectins. Docking predictions with the monosaccharides showed rhamnose and galactose-binding sites comparable to Latrophilin-1 and N-Acetylgalactosamine-binding in a different site. The effects of RpLec gene silencing on levels of infecting Trypanosoma cruzi Dm 28c and intestinal bacterial populations in the R. prolixus midgut were studied by injecting RpLec dsRNA into the R. prolixus hemocoel. Whereas T. cruzi numbers remained unchanged compared with the controls, numbers of bacteria increased significantly. The silencing also induced the up regulation of the R. prolixus defC (defensin) expression gene. These results with RpLec reveal the potential importance of this little studied molecule in the insect vector immune response and homeostasis of the gut bacterial microbiota.

First genotyping of Trypanosoma cruzi from naturally infected Triatoma juazeirensis, Triatoma melanica and Triatoma sherlocki from Bahia State, Brazil.

Many previous studies have shown a great phylogenetic and biological variability of Trypanosoma cruzi using different molecular and biochemical methods. Populations of T. cruzi were initially clustered into two main lineages called TcI and TcII by the size of the mini-exon PCR product. In the present study, 33 isolates derived from three triatomine taxa, which belong to the Triatoma brasiliensis species complex (Triatoma juazeirensis, Triatoma melanica and Triatoma sherlocki); collected in three distinct areas of Bahia state were characterized by PCR. The isolates were identified by the size of the mini-exon gene, 18S rRNA and 24Sα rRNA amplicons. T. cruzi isolates obtained in sylvatic and intradomiciliar ecotopes, derived from T. juazeirensis and T. melanica, were identified as TcI while the parasites originated from T. sherlocki were characterized as TcI and TcII genotypes, respectively. Those species are present in sylvatic ecotopes but are able to infest intradomiciliar areas. Therefore, it would be important to maintain studies in those localities of Bahia and further investigate the possibilities of Chagas disease transmission. Human disease may occur by any T. cruzi genotype and not only by TcII as it is the case in Amazonia.

Are Members of the Triatoma brasiliensis (Hemiptera, Reduviidae) Species Complex Able to Alter the Biology and Virulence of a Trypanosoma cruzi Strain?

Trypanosoma cruzi is the causative agent of Chagas disease, transmitted to humans and mammals by blood-sucking hemipteran insects belonging to the Triatominae subfamily. The two main genotypes of T. cruzi (TcI and TcII) differ in many characteristics concerning their genetic profile. Despite the extensive literature on vectors and the etiologic agent, several interactive aspects between these two elements of Chagas disease are still waiting to be further clarified. Here, biological and histological features resulting from the interaction between Albino Swiss mice and T. cruzi isolate PB913 after passages through vectors of the Triatoma brasiliensis species complex were evaluated. Comparing the four members of the T. brasiliensis species complex-Triatoma brasiliensis brasiliensis Neiva, Triatoma brasiliensis macromelasoma Galvão, Triatoma melanica Neiva & Lent, and Triatoma juazeirensis Costa & Felix-no significant differences in parasitemia of the infected mice were observed. At 20 days post-infection, the highest number of parasites was observed in the group of mice that were infected with parasites obtained from T. b. macromelasoma. Tropism of the parasites to different organs such as heart, bladder, and skeletal muscles followed by inflammatory cell infiltrates was observed with quantitative and qualitative differences. Even though the four members of the T. brasiliensis species complex differ in their geographical distribution, morphology, biology, ecology, and genetics, no significant influence on the parasitemia of the T. cruzi PB913 isolate was detected. After evaluation of the tissue samples, a higher pathogenicity of parasites obtained from T. b. brasiliensis was noticeable.

Genotype variation of Trypanosoma cruzi isolates from different Brazilian biomes.

Chagas disease is an enzootic disease, in which the flagellate Trypanosoma cruzi infects a large variety of animals. Humans are accidentally infected due to the migration into wild environments. To identify T. cruzi discrete typing units (DTUs), 19 Brazilian isolates from different biomes and hosts were analyzed by PCR amplification of 24Sα rRNA, 18S rRNA and mini-exon gene sequences. The majority of the isolates was classified as TcIIb (TcII) but subtypes TcIIc (TcIII) and TcIId (TcV) were also identified. In addition, in monkeys TcI was detected.

Sequence characterization and expression patterns of defensin and lysozyme encoding genes from the gut of the reduviid bug Triatoma brasiliensis.

The cDNAs encoding an intestinal defensin (def1) and lysozyme (lys1) of the reduviid bug Triatoma brasiliensis have been amplified by PCR using specific oligonucleotide primers and 5'- and 3'-RACE, cloned and sequenced. The 576 bp clone has an open reading frame of 282 bp and encodes a pre-prodefensin with 94 amino acid residues, containing a putative signal and activation peptide cleavage site at Ser19 and Arg51, respectively. The genomic DNA contains a second defensin gene with similar characteristics, 88.3% identity and also one intron of 107 nucleotides. The 538 bp clone has an open reading frame of 417 bp, encoding a pre-lysozyme with 139 amino acid residues. The putative signal peptide is cleaved at alanine 18. Using whole mount in situ hybridization, high expression of both genes has been found, distributed uniformly throughout the entire cardia and the blood-storing stomach and to a much lower extent in the digesting small intestine. Using quantitative real-time PCR, the expression level of def1 was also shown to be very low in small intestine, rectum and salivary glands; in the stomach, expression was 500-2500 times higher than in the cardia and fat body. No expression of lys1 could be detected in the salivary glands and rarely a very low expression in the small intestine, rectum and fat body. Lys1 expression in the stomach was 60-300 times higher than in the cardia. Comparing the levels in unfed fifth instars and up to 15 days after feeding, a strong def1 induction was evident in the fat body at 15 days after feeding and in the stomach a maximum level of def1 and lys1 at 5 days after feeding.

Trypanosoma cruzi I and Trypanosoma cruzi II: recognition of sugar structures by Arachis hypogaea (peanut agglutinin) lectin.

Epimastigote culture forms of different isolates of Trypanosoma cruzi from different mammal hosts, humans, and vectors were tested with FITC-conjugated peanut agglutinin lectin (PNA-FITC). The parasites maintained in axenic medium, liver infusion tryptose. were evaluated by flow cytometric analyses; whereas T. cruzi I (Tcl), which is associated with the sylvatic transmission cycle, was labeled in high percentages with PNA (88-99.2%), T. cruzi II (TcII) (parasites associated with domiciliar cycle) and T. cruzi, zymodeme 3 (Tc/Z3) (also associated with the sylvatic cycle) were labeled in low percentages (TcII, 0-26% and Tc/Z3, 0-12.6%). It was demonstrated that it is possible to differentiate the 2 main T. cruzi subpopulations, TcI and TcII, using Arachis hypogaea. These results also showed a higher variability in TcII in terms of PNA binding.

Biological activities of Curcuma longa L

There are several data in the literature indicating a great variety of pharmacological activities of Curcuma longa L. (Zingiberaceae), which exhibit anti-inflammatory, anti-human immunodeficiency virus, anti-bacteria, antioxidant effects and nematocidal activities. Curcumin is a major component in Curcuma longa L., being responsible for its biological actions. Other extracts of this plant has been showing potency too. In vitro, curcumin exhibits anti-parasitic, antispasmodic, anti-inflammatory and gastrointestinal effects; and also inhibits carcinogenesis and cancer growth. In vivo, there are experiments showing the anti-parasitic, anti-inflammatory potency of curcumin and extracts of C. longa L. by parenteral and oral application in animal models. In this present work we make an overview of the pharmacological activities of C. longa L., showing its importance