Differential parasitological, molecular, and serological detection of Trypanosoma cruzi I, II, and IV in blood of experimentally infected mice

Evaluation of a novel Tc-24 recombinant antigen ELISA for serologic testing for Trypanosoma cruzi in dogs

Chagas disease is a parasitic infection caused by Trypanosoma cruzi. Diagnosis of chronic Chagas disease in dogs relies on limited serological test options. This study used a new Tc-24 recombinant antigen ELISA on an archival set of 70 dog serum samples from multi-dog kennel environments in Texas subjected to three existing Chagas serological tests. Tc-24 ELISA produced a quantitative result and could detect anti-T. cruzi antibodies in dogs with high sensitivity and specificity. Comparing individual tests to Tc-24 ELISA resulted in strong associations and correlations, which suggest that Tc-24 ELISA is a reliable and accurate diagnostic tool for dogs with a single test.

Oral Chagas Disease in Colombia-Confirmed and Suspected Routes of Transmission

Chagas disease (CD) remains endemic throughout many regions of Colombia despite implementing decades of vector control strategies in several departments. Some regions have had a significant decrease in vectorial transmission, but the oral ingestion of Trypanosoma cruzi through consumption of contaminated food and drink products is increasingly described. This form of transmission has important public health relevance in Colombia due to an increase in reported acute CD cases and clinical manifestations that often lead to significant morbidity and mortality. Oral CD in Colombia has been associated with the consumption of contaminated fruit juices, such as palm wine, sugar cane, or tangerine juice and water for consumption, or contaminated surfaces where food has been prepared. Another interesting route of oral transmission includes ingestion of unbeknownst infected armadillos' blood, which is related to a traditional medicine practice in Colombia. Some earlier reports have also implemented consumption of infected bush meat as a source, but this is still being debated. Within the Amazon Basin, oral transmission is now considered the principal cause of acute CD in these regions. Furthermore, new cases of acute CD are now being seen in departments where CD has not been documented, and triatomine vectors are not naturally found, thus raising suspicion for oral transmission. The oral CD could also be considered a food-borne zoonosis, and odoriferous didelphid secretions have been implemented in contaminating the human dwelling environment, increasing the risk of consumption of infectious metacyclic trypomastigotes. In this article, we will discuss the complex transmission dynamics of oral CD in Colombia and further examine the unique clinical manifestations of this route of infection. New insights into the oral transmission of Trypanosoma cruzi are being discovered in Colombia, which can help bring increased awareness and a better understanding of this neglected tropical disease to reduce the burden of CD throughout Latin America.

Discrete Typing Units of Trypanosoma cruzi Identified by Real-Time PCR in Peripheral Blood and Dejections of Triatoma infestans Used in Xenodiagnosis Descriptive Study

Chagas disease (ChD) is a vector zoonosis native to the American continent caused by the protozoan parasite Trypanosoma cruzi; the biological vectors are multiple species of hematophagous insects of the family Triatominae. A relevant aspect in the host–parasite relationship is the identification of the various genotypes of T. cruzi called discrete typing units (DTU) that circulate in mammals and vectors. In Chile, it has been described that the DTUs TcI, TcII, TcV, and TcVI circulate in infected humans, vectors, and wild animals. Identifying DTUs has acquired clinical importance, since it has been suggested that different genotypes could cause distinct pathologies, circulate in different geographical areas, and present different sensitivities to trypanocidal drugs. In this study, circulating T. cruzi DTUs in peripheral blood and Triatoma infestans dejections used in xenodiagnosis (XD) were amplified by qPCR in 14 Chilean patients with chronic ChD from highly endemic areas. More positive samples were detected by XD compared to peripheral blood samples, and 64.28% of the cases were simple infections and 35.72% mixed, with a statistically significant difference in the frequency of TcV DTU. This study would suggest that T. infestans from Chile is more competent to amplify one DTU over others, probably due to a process of co-evolution.

Suspected vertical transmission of Chagas disease caused by DTU TcIV in an infection probably transmitted orally, during anoutbreak in the Brazilian Amazon

This study describes difficulties in the monitoring of a child born during an oral outbreak of Chagas disease, in which there are several indications that the transmission occurred through the congenital route: 1. the mother was in the third trimester of pregnancy when she was infected; 2. She presented high parasitemia at the time of delivery; 3. In both, the mother and her daughter, T. cruzi was classified as DTU TcIV. The parasites were not found in the blood at birth and the infection was detected only three months later in an asymptomatic infant. As the mother and her child live in a highly endemic area, vector transmission could not be excluded during this period.

Galectin-3 mediates survival and apoptosis pathways during Trypanosoma cruzi-host cell interplay

Neglected tropical diseases, such as Chagas disease caused by the protozoa Trypanosoma cruzi, affect millions of people worldwide but lack effective treatments that are accessible to the entire population, especially patients with the debilitating chronic phase. The recognition of host cells, invasion and its intracellular replicative success are essential stages for progression of the parasite life cycle and the development of Chagas disease. It is predicted that programmed cell death pathways (apoptosis) would be activated in infected cells, either via autocrine secretion or mediated by cytotoxic immune cells. This process should play a key role in resolving infections by hindering the evolutionary success of the parasite. In this research, we performed assays to investigate the role of the lectin galectin-3 (Gal3) in parasite-host signaling pathways. Using cells with endogenous levels of Gal3 compared to Gal3-deficient cells (induced by RNA interference), we demonstrated that T. cruzi mediated the survival pathways and the subverted apoptosis through Gal3 promoting a pro-survival state in infected cells. Infected Gal3-depleted cells showed increased activation of caspase 3 and pro-apoptotic targets, such as poly (ADP-ribose) polymerase (PARP), and lower accumulation of anti-apoptotic proteins, such as c-IAP1, survivin and XIAP. During the early stages of infection, Gal3 translocates from the cytoplasm to the nucleus and must act in survival pathways. In a murine model of experimental infection, Gal3 knockout macrophages showed lower infectivity and viability. In vivo infection revealed a lower parasitemia and longer survival and an increased spleen cellularity in Gal3 knockout mice with consequences on the percentage of T lymphocytes (CD4⁺ CD11b⁺) and macrophages. In addition, cytokines such as IL-2, IL-4, IL-6 and TNF-α are increased in Gal3 knockout mice when compared to wild type genotype. These data demonstrate a Gal3-mediated complex interplay in the host cell, keeping infected cells alive long enough for infection and intracellular proliferation of new parasites. However, a continuous knowledge of these signaling pathways should contribute to a better understanding the mechanisms of cell death subversion that are promoted by protozoans in the pathophysiology of neglected diseases such as Chagas disease.

Trypanosoma Found in Synanthropic Mammals from Urban Forests of Paraná, Southern Brazil

Trypanosoma cruzi is a parasitic protozoan that infects a diversity of hosts constituting the cycle of enzootic transmission in wild environments and causing disease in humans (Chagas disease) and domestic animals. Wild mammals constitute natural reservoirs of this parasite, which is transmitted by hematophagous kissing bugs of the family Reduviidae. T. cruzi is genetically subdivided into six discrete typing units (DTUs), T. cruzi (Tc)I to TcVI. In Brazil, especially in the state of Paraná, TcI and TcII are widely distributed. However, TcII is less frequently found in wild reservoirs and triatomine, and more frequently found in patients. The goal of this study was to investigate the natural occurrence of T. cruzi in wild synanthropic mammals captured in urban forest fragments of the Atlantic Forest of Paraná, southern Brazil. In this way, 12 opossums and 35 bats belonging to five species were captured in urban forest parks of the city of Maringá, Paraná, an area considered endemic for Chagas disease. PCR-kinetoplast DNA molecular diagnostic reveals Trypanosoma sp. infection in 12 (100%) Didelphis albiventris and 10 (40%) Artibeus lituratus. In addition to demonstrating the presence of Trypanosoma in the two groups of mammals studied, we obtained an isolate of the parasite genotyped as TcII by amplification of the cytochrome oxidase II gene by PCR, followed by restriction fragment length polymorphism with AluI, and confirmed by PCR of rDNA 24Sα. This is the first record of the encounter in wild mammals of Trypanosoma DNA (in A. lituratus) and T. cruzi DTU TcII (in D. albiventris) in the state of Paraná.

Uncovering Trypanosoma spp. diversity of wild mammals by the use of DNA from blood clots

Trypanosoma spp. infection in wild mammals is detected mainly through parasitological tests that usually display low sensitivity. We propose the use of DNA extracted directly from blood clots (BC), which are neglected sources of DNA for diagnosis and identification of Trypanosoma spp. This approach followed by nested PCR targeting the 18S SSU rDNA demonstrated to be sensitive and suitable to evaluate the diversity of trypanosomes infecting sylvatic mammals, including subpatent and mixed infections. Infection was detected in 95/120 (79.2%) samples from bats, carnivores and marsupials that included negative serological and hemoculture testing mammals. Thirteen Trypanosoma spp. or Molecular Operational Taxonomic Units (MOTUs) were identified, including two new MOTUs. The high diversity of trypanosomes species and MOTUs infecting bats and marsupials showed that these hosts can be considered as bio-accumulators of Trypanosoma spp., with specimens of Didelphis spp. displaying the highest trypanosome diversity. The use of blood clots allowed direct access to non-culturable parasites, mixed infections, besides bypassing the selective pressure on the parasites inherent to cultivation procedures. Trypanosoma cruzi was the species found infecting the highest number of individuals, followed by T. lainsoni. Positive PCR for T. cruzi was observed in 16 seronegative individuals and 30 individuals with negative hemocultures. Also, T. lainsoni, previously found only in rodents, showed to be capable of infecting bats and marsupials. This finding makes it clear that some species of Trypanosoma are more generalist than previously thought. Molecular diagnosis using nested PCR from DNA extracted from BC allowed the increase of the knowledge about host-spectrum and distribution of Trypanosoma spp. and allowed the identification of new MOTUs.

Germacranolide-type sesquiterpene lactones from Smallanthus sonchifolius with promising activity against Leishmania mexicana and Trypanosoma cruzi

Background

Leishmaniasis and Chagas disease are life-threatening illnesses caused by the protozoan parasites Leishmania spp. and Trypanosoma cruzi, respectively. They are known as “neglected diseases” due to the lack of effective drug treatments and the scarcity of research work devoted to them. Therefore, the development of novel and effective drugs is an important and urgent need. Natural products are an important source of bioactive molecules for the development of new drugs. In this study, we evaluated the activity of enhydrin, uvedalin and polymatin B, three sesquiterpene lactones (STLs) isolated from Smallanthus sonchifolius, on Leishmania mexicana (MNYC/BZ/62/M) and Trypanosoma cruzi (Dm28c). In addition, the in vivo trypanocidal activity of enhydrin and uvedalin and the effects of these STLs on parasites’ ultrastructure were evaluated.

Methods

The inhibitory effect of the three STLs on the growth of L. mexicana amastigotes and promastigotes as well as T. cruzi epimastigotes was evaluated in vitro. The changes produced by the STLs on the ultrastructure of parasites were examined by transmission electron microscopy (TEM). Enhydrin and uvedalin were also studied in a murine model of acute T. cruzi infection (RA strain). Serum activities of the hepatic enzymes alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase were used as biochemical markers of hepatotoxicity.

Results

The three compounds exhibited leishmanicidal activity on both parasite forms with IC₅₀ values of 0.42–0.54 μg/ml for promastigotes and 0.85–1.64 μg/ml for intracellular amastigotes. Similar results were observed on T. cruzi epimastigotes (IC₅₀ 0.35–0.60 μg/ml). The TEM evaluation showed marked ultrastructural alterations, such as an intense vacuolization and mitochondrial swelling in both L. mexicana promastigotes and T. cruzi epimastigotes exposed to the STLs. In the in vivo study, enhydrin and uvedalin displayed a significant decrease in circulating parasites (50–71%) and no signs of hepatotoxicity were detected.

Conclusions

Enhydrin, uvedalin and polymatin B possess significant leishmanicidal and trypanocidal activity on different parasite stages. These results show that these compounds may provide valuable leads for the development of new drugs against these neglected parasitic diseases.

Escaping Deleterious Immune Response in Their Hosts: Lessons from Trypanosomatids

The Trypanosomatidae family includes the genera Trypanosoma and Leishmania, protozoan parasites displaying complex digenetic life cycles requiring a vertebrate host and an insect vector. Trypanosoma brucei gambiense, Trypanosoma cruzi, and Leishmania spp. are important human pathogens causing human African trypanosomiasis (HAT or sleeping sickness), Chagas' disease, and various clinical forms of Leishmaniasis, respectively. They are transmitted to humans by tsetse flies, triatomine bugs, or sandflies, and affect millions of people worldwide. In humans, extracellular African trypanosomes (T. brucei) evade the hosts' immune defenses, allowing their transmission to the next host, via the tsetse vector. By contrast, T. cruzi and Leishmania sp. have developed a complex intracellular lifestyle, also preventing several mechanisms to circumvent the host's immune response. This review seeks to set out the immune evasion strategies developed by the different trypanosomatids resulting from parasite-host interactions and will focus on: clinical and epidemiological importance of diseases; life cycles: parasites-hosts-vectors; innate immunity: key steps for trypanosomatids in invading hosts; deregulation of antigen-presenting cells; disruption of efficient specific immunity; and the immune responses used for parasite proliferation.