Biological and isoenzymatic characterization of Trypanosoma cruzi strains isolated from sylvatic reservoirs and vectors from the state of Santa Catarina, Southern Brazil

Molecular characterization of Trypanosoma cruzi samples derived from Triatoma vitticeps and Panstrongylus geniculatus of the Atlantic rainforest, southeast Brazil

Background: In rural areas of Espírito Santo state, southeast Brazil, triatomine species attracted by light frequently invade residences. The aim of this study was to investigate the Trypanosoma cruzi discrete typing units (DTUs) harbored by these triatomines. Methods: Triatomine’s intestinal contents were examined, inoculated in mice, and the positive samples were cultivated. Flagellates obtained from infected mice hemoculture were submitted to DNA extraction using a salting-out method and to TcSC5D gene amplification. The amplified samples were sequenced, and polymorphism was analyzed for DTU identification. Results: Three hundred and ninety-four triatomines were identified: Triatoma vitticeps (90.03%), Panstrongylus geniculatus (8.89%), Panstrongylus megistus (0.54%), Panstrongylus diasi (0.27%), and Triatoma tibiamaculata (0.27%). Among the specimens, 251/394 (67.65%) presented flagellated forms similar to T. cruzi. After triatomine intestinal content inoculation into mice, 134 mice presented T. cruzi-like trypomastigotes from Tr. vitticeps and P. geniculatus and 89 samples were positive in hemoculture. Sixty-two samples were analyzed for the TcSC5D gene and TcI, TcII, TcIII, and TcIV DTUs were identified. Conclusions: We observed T. cruzi DTU diversity in Tr. vitticeps and P. geniculatus, which showed the predominance of TcII and occurrence of TcI, TcIII and TcIV. Triatomines presented high T. cruzi infection rates. Since little is known regarding the possible mammalian hosts that maintain the T. cruzi cycle, further studies are necessary to obtain a better understanding of the parasite transmission cycle in this region.

Between a bug and a hard place: Trypanosoma cruzi genetic diversity and the clinical outcomes of Chagas disease

Over the last 30 years, concomitant with successful transnational disease control programs across Latin America, Chagas disease has expanded from a neglected, endemic parasitic infection of the rural poor to an urbanized chronic disease, and now a potentially emergent global health problem. Trypanosoma cruzi infection has a highly variable clinical course, ranging from complete absence of symptoms to severe and often fatal cardiovascular and/or gastrointestinal manifestations. To date, few correlates of clinical disease progression have been identified. Elucidating a putative role for T. cruzi strain diversity in Chagas disease pathogenesis is complicated by the scarcity of parasites in clinical specimens and the limitations of our contemporary genotyping techniques. This article systematically reviews the historical literature, given our current understanding of parasite genetic diversity, to evaluate the evidence for any association between T. cruzi genotype and chronic clinical outcome, risk of congenital transmission or reactivation and orally transmitted outbreaks.

The role of sigmodontine rodents as sylvatic hosts of Trypanosoma cruzi in the Argentinean Chaco

The role of rodents in the sylvatic transmission of Trypanosoma cruzi has seldom been investigated using parasitological and molecular methods. We assessed the occurrence of T. cruzi in wild small rodents from Pampa del Indio, in the Argentinean Chaco, and identified the taxonomic status of positive rodents by sequencing a fragment of cytochrome b gene (cytb) and performing BLAST searches and phylogenetic analyses. A total of 176 Sigmodontinae rodents was captured in six surveys using 5425 trap-nights in a wide range of sylvatic habitats between 2009 and 2011. Host infection was determined by xenodiagnosis and by polymerase chain reaction amplification of the hyper-variable region of kinetoplast DNA minicircles of T. cruzi (kDNA-PCR) from blood samples. None of the 176 rodents examined was xenodiagnosis-positive. The prevalence of infection determined by kDNA-PCR from blood samples was 16.2% (95% confidence interval, 10.1-21.9%). Half of the infections detected by kDNA-PCR were confirmed by nuclear satellite DNA-PCR or by kDNA-PCR of the rectal contents of xenodiagnostic bugs. The 24 positive specimens were assigned to eight species, providing the first records of T. cruzi in Akodon montensis, Akodon toba, Graomys chacoensis, and Oligoryzomys chacoensis. The occurrence of T. cruzi infection in Oligoryzomys nigripes, Calomys callosus, Necromys lasiurus and Oecomys sp. (most probably Oecomys mamorae) from the Gran Chaco is also reported for the first time. Although sigmodontine rodents were frequently infected, the intensity of bug rectal infection with T. cruzi was below the detection limit of xenodiagnosis (subpatent infectiousness to bugs), indicating they had a low reservoir host competence.

Biological, biochemical and molecular features of Trypanosoma cruzi strains isolated from patients infected through oral transmission during a 2005 outbreak in the state of Santa Catarina, Brazil: its correspondence with the new T. cruzi Taxonomy Consensus (2009)

We examined strains of Trypanosoma cruzi isolated from patients with acute Chagas disease that had been acquired by oral transmission in the state of Santa Catarina, Brazil (2005) and two isolates that had been obtained from a marsupial (Didelphis aurita) and a vector (Triatoma tibiamaculata). These strains were characterised through their biological behaviour and isoenzymic profiles and genotyped according to the new Taxonomy Consensus (2009) based on the discrete typing unities, that is, T. cruzi genotypes I-VI. All strains exhibited the biological behaviour of biodeme type II. In six isolates, late peaks of parasitaemia, beyond the 20th day, suggested a double infection with biodemes II + III. Isoenzymes revealed Z2 or mixed Z1 and Z2 profiles. Genotyping was performed using three polymorphic genes (cytochrome oxidase II, spliced leader intergenic region and 24Sα rRNA) and the restriction fragment length polymorphism of the kDNA minicircles. Based on these markers, all but four isolates were characterised as T. cruzi II genotypes. Four mixed populations were identified: SC90, SC93 and SC97 (T. cruzi I + T. cruzi II) and SC95 (T. cruzi I + T. cruzi VI). Comparison of the results obtained by different methods was essential for the correct identification of the mixed populations and major lineages involved indicating that characterisation by different methods can provide new insights into the relationship between phenotypic and genotypic aspects of parasite behaviour.

Biological behaviour in mice of Trypanosoma cruzi isolates from Amazonas and Paraná, Brazil

The biological behaviour of 23 Trypanosoma cruzi isolates in Swiss mice was compared. Nineteen isolates were obtained from patients in the acute phase of Chagas disease (13), sylvatic reservoir hosts (Didelphis marsupialis) (3), and triatomine bugs (Rhodnius robustus) (3) from four regions of the State of Amazonas (AM). Four isolates were obtained from chronic chagasic patients in the State of Paraná (PR): three autochthones, and one allochthone from the State of Minas Gerais. Only one isolate was unable to infect the mice. The AM and PR isolates showed the largest number of significant differences from each other. The former had lower mean values in the pre-patent (5.4 days) and patent (4.6 days) periods (PP), with the parasitaemia (Pmax) reaching a peak of 9.9×10(4) blood trypomastigotes (BT)/mL of blood by the 7th day following inoculation. The AM isolates also had higher positivity to fresh-blood examination (FBE) (84.1%) compared to haemoculture (HC) (58.7%) and polymerase chain reaction (PCR) (33.3%), in addition to higher mortality (2.9%). The PR isolates had higher values for PP (18.5 days) and Pmax (99.9×10(4)BT/mL) as well as higher positivity to FBE (87.2%), HC (100%), and PCR (83.3%). The correlations between the biological behaviour of the T. cruzi isolates and the clinical and epidemiological characteristics of Chagas disease are discussed.

Trypanosoma cruzi: multiplex PCR to detect and classify strains according to groups I and II

A multiplex PCR was developed for simultaneous detection of Trypanosoma cruzi DNA and classification of the parasite strain into groups I and II. As little as 10fg of T. cruzi DNA could be detected by multiplex PCR. The technique was shown to be specific for T. cruzi DNA, since no PCR amplification products were obtained with DNA from other tripanosomatid species. Multiplex PCR was validated by assaying genomic DNA from 34 strains of T. cruzi that had been previously characterized; 24 blood samples from experimentally-infected mice and non-infected controls; 20 buffy coat samples from patients in the acute phase of Chagas disease and non-infected individuals, and 15 samples of feces from naturally-infected Triatoma infestans. T. cruzi samples from patients and from Y strain-infected mice were classified by multiplex PCR as T. cruzi II and samples from T. infestans and Colombiana strain-infected mice as T. cruzi I.

Characterization of Trypanosoma cruzi isolated from humans, vectors, and animal reservoirs following an outbreak of acute human Chagas disease in Santa Catarina State, Brazil

During March 2005, 24 cases of acute human Chagas disease were detected in Santa Catarina State, southern Brazil, all of them related to the ingestion of Trypanosoma cruzi-contaminated sugar cane juice. Following field studies allowed the isolation of 13 T. cruzi strains from humans, opossums (Didelphis aurita and Didelphis albiventris), and vectors (Triatoma tibiamaculata). The isolated strains were characterized by multilocus enzyme electrophoresis (MLEE) and analysis of the spliced-leader and 24Salpha rRNA genes. The assays revealed that all strains isolated from humans belong to the TcII group but revealed a TcII variant pattern for the phosphoglucomutase enzyme. Strains isolated from opossums also showed a TcI profile in all analysis, but strains isolated from triatomines revealed a mixed TcI/TcII profile by MLEE. No indication of the presence of Trypanosoma rangeli was observed in any assay. Considering that mixed strains (TcI/TcII) were isolated from triatomines in an area without active vectorial transmission to humans and that all strains isolated from humans belong to the TcII group, our results show that T. cruzi TcI and TcII groups are circulating among reservoirs and vectors in southern Brazil and indicate that selection toward TcII group in humans may occur after ingestion of a mixed (TcI/TcII) T. cruzi population.

Infectivity for mice of Trypanosoma cruzi I and II strains isolated from different hosts

In this paper, the infectivity for mice of Trypanosoma cruzi I and II strains isolated from sylvatic animals, triatomines, and humans is determined using fresh blood examination, hemoculture, culture of macerated organs, and polymerase chain reaction (PCR). Six strains were considered to have low infectivity (9.1-18.2%), five medium (27.3-45.4%), and one high (100.0%). Infectivity of T. cruzi strains isolated from sylvatic animals was significantly higher than that of strains isolated from humans and triatomines (p=0.0141). No significant difference was observed between the infectivity of T. cruzi I and II strains. The parasite was detected by fresh blood examination in one strain, by hemoculture and culture of macerated organs in four strains, and by PCR in all strains. We conclude that the infectivity is related to the host from which the strains were isolated, but the infectivity is not related to the genetic group of the parasite. We also conclude that the majority of the strains studied have low and medium infectivity for mice, and that PCR is an important tool to detect T. cruzi in strains with this biological characteristic.

Differential infectivity and immunopathology in murine experimental infections by two natural clones belonging to theTrypanosoma cruziI lineage

Immunopathology of Chagas' disease in Balb/c mice infected with 2Trypanosoma cruziclones, belonging to theT. cruziI lineage and presenting differentin vitrovirulence (P/209 cl1>SO34 cl4) was compared. In the acute phase, evading mechanisms such as parasite-induced lymphocyte polyclonal activation and T cell immunosuppression were higher in mice infected with the clone giving a higher parasitaemia (P/209 cl1). A similar increase of non-specific isotypes was observed in both infections with IgG2a prevalence. Interestingly, CD8+ cell hypercellularity and lymphocyte immunosuppression were observed during the chronic phase (245 days post-infection) in mice infected by the most virulent clone. In the same way, the parasite-specific antibody response was more intense in P/209 cl1-infected mice over the acute phase. During the chronic phase this response remarkably dropped down in SO34 cl4-infected mice exclusively. Finally, P/209 cl1-infected mice presented a more severe inflammation and tissue damage in heart and quadriceps than SO34 cl4-infected mice. This comparative study showed differences between the two clones: a higher virulencein vivobeing clearly associated with a greater ability to induce evasion mechanisms and severe tissue damage.

Biochemical characterization of new strains of Trypanosoma cruzi and T. rangeli isolates from Peru and Mexico

Seven trypanosome stocks isolated have been characterized by lectin agglutination, isoenzyme analysis, and the end products excreted. The stocks were isolated from different geographic areas-one from Mexico (TM5), and six from Peru, four of these isolated from different species of triatoma (TP504, TP702, TP704 and TP706), the other two isolated from the salivary glands of Rhodnius ecuadorensis (TRa605 and TRa606). Additionally, one strain of Trypanosoma cruzi isolated from a human case (strain TC-Maracay) and one strain of T. rangeli (TRa, Cajamarca-Peru strain), characterized and maintained in our laboratory, were used as reference strains. According to statistical study, the stocks were grouped into three clusters: (1) cluster I included the reference strain of T. cruzi (TC-Maracay); (2) cluster II was subdivided into two groups-subcluster IIA for the Mexican isolate (TM5) and subcluster IIB for the Peruvian ones, isolated from the salivary glands of Rhodnius ecuadorensis (TRa 605 and TRa 606) and the reference strain T. rangeli (TRa); these two new isolates were classified as T. rangeli; and (3) cluster III for the rest of the Peruvian isolates, which should be considered at least as a different strain from the T. cruzi strain Maracay. We show that the identification of T. cruzi and T. rangeli in mixed infections is readily achieved by biochemical methods. These findings identified three clusters of Mexican and Peruvian stocks that correlate with geographic origin, although assignment to a T. cruzi linage was not possible.

Trypanosoma cruzi infection in Didelphis marsupialis in Santa Catarina and Arvoredo Islands, southern Brazil

Between 1984 and 1993 the prevalence of the Trypanosoma cruzi infection in opossums (Didelphis marsupialis) was studied in Santa Catarina and Arvoredo Islands, State of Santa Catarina, Brazil. The association of the triatomine bug Panstrongylus megistus with opossums nests and the infection rate of these triatomines by T. cruzi was also studied. Thirteen different locations were studied in Santa Catarina Island (SCI), in which 137 D. marsupialis were collected. Sixty two opossums were collected at the Arvoredo Island (AI), located 12 miles north from SCI. All captured animals were submitted to parasitological examinations that revealed the presence of T. cruzi in 21.9% of the opossums captured in SCI and 45.2% among opossums captured in the AI. The presence of P. megistus was detected in most of the D. marsupialis nests collected in the SCI, however, in the non-inhabited AI only eight triatomines were collected during the whole study. The presence of T. cruzi-infected D. marsupialis associated with P. megistus in human dwellings in the SCI, and the high infection rate of D. marsupilais by T. cruzi in the absence of a high vector density are discussed.

Trypanosoma cruzi: parasitaemia produced in mice does not seem to be related to in vitro parasite-cell interaction

The interaction of Trypanosoma cruzi strains producing subpatent or high parasitaemia in mice with mouse macrophages, Vero and L929 cells was evaluated using tissue culture trypomastigotes. Macrophages were the cells most readily infected while Vero cells presented the highest parasite intracellular multiplication rates. Subpatent strains were equal or more infective than the high parasitaemia. Due to the small number of strains, no correlation could be established between the zymodemes and parasitaemia or parasite-cell interaction in vitro. However parasitaemia in mice does not seem to be related to in vitro parasite-cell interaction.