Resumen Chagas es una endemia que afecta a Latinoamérica con alto impacto biomédico y social. Es un caso único en la historia médica donde primero se descubre un microorganismo y luego la enfermedad que produce. El “redescubrimiento” de su importancia se origina en la Argentina, con los estudios de Salvador Mazza y colaboradores de diferentes provincias en la Misión de Estudios de Patología Regional Argentina (MEPRA). A pesar de su magnitud, es objeto de adjetivaciones como “endemia olvidada”, “enfermedad silenciosa”, “mal escondido” y está incluida entre las “enfermedades desatendidas”. Originalmente era una endemia rural, actualmente se ha urbanizado y globalizado por migraciones y propagación interhumana, principalmente por la transmisión madre-hijo. Además, la vía oral hace años adquirió importancia epidemiológica. El diagnóstico de laboratorio está protocolizado y es posible realizarlo incluso en laboratorios de baja complejidad. Para la prevención, interferir en la cadena epidemiológica que incluye reservorios domésticos es una estrategia que puede contribuir a disminuir la infección en zonas con transmisión vectorial. La vacunación con Trypanosoma rangeli, parásito inmunológicamente similar a Trypanosoma cruzi pero no patógeno, ha demostrado su eficacia para proteger perros y cobayos contra la infección por T. cruzi. Basso et al. han estudiado además mecanismos protectores, demostrando la importancia de la inmunidad innata, además de la clásica inmunidad adaptativa. Por último, este artículo aborda aspectos académicos, sociales y bioéticos, enfatizando la importancia de la enseñanza de Chagas en ciencias de la salud y la necesidad de garantizar los principios y valores bioéticos aplicables a poblaciones vulnerables.

Resumo Chagas é uma doença endêmica que afeta à América Latina com alto impacto biomédico e social. É um caso único na história da Medicina, onde primeiro se descobre um microrganismo e depois a doença que ele produz. A “redescoberta” de sua importância tem origem na Argentina, com os estudos de Salvador Mazza e colaboradores de diferentes províncias na Missão de Estudos de Patologia Regional Argentina (MEPRA). Apesar de sua importância, é objeto de adjetivos como “endemia esquecida”, “doença silenciosa”, “mal escondido” e está incluída entre as “doenças negligenciadas”. Originalmente endemia rural, agora é urbanizada e globalizada por migrações e disseminação inter-humana, principalmente a transmissão mãe-filho. Por outro lado, a transmissão oral faz anos adquiriu importância epidemiológica. O diagnóstico laboratorial é protocolizado e é possível realizá-lo mesmo em laboratórios de baixa complexidade. Quanto à prevenção, a interrupção da cadeia epidemiológica que inclui reservatórios domésticos, é uma estratégia que pode contribuir a reduzir a infecção em áreas com transmissão vetorial. A vacinação com Trypanosoma rangeli, parasita imunologicamente semelhante ao Trypanosoma cruzi, mas não patogênico, tem se mostrado eficaz na proteção de cães e cobaias contra a infecção por T. cruzi. Basso et al. estudaram os mecanismos protetores, demonstrando a importância da imunidade inata, além da imunidade adaptativa clássica. Finalmente, o artigo aborda aspectos acadêmicos, sociais e bioéticos, enfatizando a importância do ensino de Chagas em Ciências da Saúde, e a necessidade de garantir os princípios e valores bioéticos aplicáveis às populações vulneráveis.

Abstract Chagas disease is an endemic disease that affects Latin America with high biomedical and social impact. This work addresses aspects and particularities that characterise this disease. It is a unique case in medicine as the microorganism was discovered before the disease it causes. The re-discovery of its relevance had its origin in Argentina, due to studies conducted by Salvador Mazza and collaborators from various provinces, within the Mission of Regional Pathology Studies from Argentina (MEPRA). Notwithstanding its importance, it is often described as “forgotten endemic disease”, “silent disease”, “hidden illness”, and it is included among the “neglected diseases”. Originally considered as rural endemic, nowadays it is urbanised and globalised, due to migrations and inter-human propagation, mainly by mother-child transmission. On the other hand, oral transmission is considered now of epidemiological relevance. Laboratory diagnosis is protocolised and it is possible to carry it out even in low complexity laboratories. Concerning disease prevention, interrupting the epidemiological chain that includes domestic reservoirs is a strategy that can contribute to reducing the infection in areas where it is vector-borne. Vaccination with Trypanosoma rangeli, a parasite immunologically similar to Trypanosoma cruzi but which is nonpathogenic, has demonstrated its efficacy in protecting dogs and guinea pigs against T. cruzi infection. Basso et al. have studied the importance of innate immunity, in addition to the classic adaptive immunity. Finally, this article addresses academic, social and bioethical aspects, emphasizing the importance of an adequate education in the health science field, as well as the need to guarantee bioethical principles and values regarding vulnerable populations.

Resumen Hay poca información sobre la inmunidad innata de los triatominos contra Trypanosoma rangeli, un parásito infeccioso para el humano, aunque no patógeno, y T. cruzi, el agente causal de la enfermedad de Chagas. En este trabajo se buscó llenar ese vacío mediante el estudio de la actividad tripanolítica in vitro de la hemolinfa de insectos no infectados con T. rangeli o T. cruzi. Se examinaron ocho especies de triatominos: Rhodnius prolixus, R. robustus, R. colombiensis, R. pallescens, R. pictipes, Triatoma dimidiata, T. maculata, y Panstrongylus geniculatus. La hemolinfa de las colonias de laboratorio de R. prolixus y R. robustus presentó una fuerte actividad tripanolítica durante las primeras 14 horas de incubación con los parásitos, evidenciando 81 y 90 % de lisis para los genotipos C y E de T. rangeli y 95 % para la unidad taxonómica discreta (DTU) de TcII, 94 % para TcV, 96% para TcVI, 94 % para Tcbat y 90 % para Tcmarinkellei. No se detectó lisis a las 14 ni a las 24 horas de incubación de los parásitos con las hemolinfas de colonias de laboratorio de R. pictipes, R. pallescens, P. geniculatus y T. maculata. Se registraron resultados idénticos (ausencia de lisis) con la hemolinfa de colonias de laboratorio de R. colombiensis y T. dimidiata y de especímenes capturados en ambientes selváticos. La actividad lítica de la hemolinfa fue similar en cultivos recientes de TcII (95 % de lisis) y en aquellos mantenidos por periodos prolongados (96 % de lisis). La actividad lítica de la hemolinfa de R. prolixus fue similar en ninfas, machos y hembras y en insectos alimentados con sangre de gallina o sangre de ratón. Este es el primer estudio comparativo de la actividad tripanolítica en la hemolinfa de diferentes especies de triatominos contra genotipos de T. rangeli y T. cruzi. Aunque la estructura química de los factores líticos, así como los mecanismos que determinan su expresión, aún no se han establecido completamente, su identificación permitirá comprender mejor la inmunidad innata de los triatominos y su papel en la trasmisión de los tripanosomas.

Abstract There is limited information about the innate immunity of triatomines against Trypanosoma rangeli, an infectious, non-pathogenic human parasite, and T. cruzi, the causative agent of Chagas' disease. This study aimed at addressing this gap by studying the in vitro trypanolytic hemolymph activity from insects not infected by T. rangeli or T. cruzi. Eight triatomine species were examined including Rhodnius prolixus, R. robustus, R. colombiensis, R. pallescens, R. pictipes, Triatoma dimidiata, T. maculata, and Panstrongylus geniculatus. The hemolymph of R. prolixus and R. robustus laboratory colonies demonstrated strong trypanolytic activity during the first 14 hours of parasite incubation with 81% lysis for the T. rangeli C genotype, 90% for the E genotype, 95% for T. cruzi discrete taxonomic unit (DTU) TcII, 94% for TcV, 96% for TcVI, 94% for Tcbat, and 90% for Tcmarinkellei. No lysis activity was detected 14 or 24 hours after parasite incubation with the hemolymph of insects from R. pictipes R. pallescens, P. geniculatus, and T. maculata colonies. Identical results (absence of lysis) were observed using hemolymph from R. colombiensis and T. dimidiata laboratory colonies and specimens captured in sylvatic environments. The hemolymph lytic activity against recently obtained cultures (95% decrease in live parasite count) and long-term T. cruzi TcII ones (96% decrease) was similar. Lytic activity was similar in hemolymph from R. prolixus nymphs, males and females and insects fed on chicken or mouse blood. This is the first comparative study of the trypanolytic activity of hemolymph from different triatomine species against T. rangeli and T. cruzi genotypes. Although the chemical structures of such lysis factors and the mechanisms determining their expression have not been fully determined, their identification furthers our understanding of triatomines' innate immunity and their role in Trypanosoma transmission.

Abstract INTRODUCTION: Trypanosoma rangeli is a protozoan that infects several domestic and wild mammals and shows significant distribution in Latin American countries. T. rangeli infection is similar to Chagas disease, both in diagnostic and prophylactic terms. Thus, the objective of this work was to review the diagnostic aspects and use of T. rangeli as an immunogen for Trypanosoma cruzi infection. METHODS: For this elaboration, Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were adopted with descriptors derived from the Medical Subject Headings (MeSH) platform in the PubMed/MEDLINE and SciELO databases. The inclusion criteria were defined as original articles on "Trypanosoma rangeli" and diagnostic aspects of T. rangeli infection in humans and/or research on the possible vaccines developed using T. rangeli strains for T. cruzi infection. RESULTS: After applying the inclusion and exclusion criteria, 18 articles were procured, of which 4 addressed research on the possible vaccines developed using T. rangeli for T. cruzi infection in vertebrates and the remaining 14 predominantly dealt with the diagnostic aspects of T. rangeli infection in humans. CONCLUSIONS: In this study, we formulated a compilation of the essential literature on this subject, emphasizing the need for more accurate and accessible techniques for the differential diagnosis of infections caused by both protozoa, and underscored several prospects in the search for a vaccine for Chagas disease.

Abstract INTRODUCTION: Trypanosomes can infect humans and animals. This is the first record of the occurrence of Trypanosoma evansi in Rondônia. METHODS: Blood samples were collected from 7 dogs and 22 humans. Furthermore, triatomines and tabanids were collected. RESULTS: It was observed that 42.8% of the dogs tested positive for T. evansi and 14.3% presented mixed infection; 15% of the triatomines tested positive for flagellates identified as T. cruzi TCI (3 specimens), T. cruzi TCI, and T. rangeli (1 specimen), and one with T. cruzi TCV. Two tabanids were infected with T. theileri. CONCLUSIONS: These findings may benefit vector control strategies.

Abstract INTRODUCTION Rhodnius stali infection by Trypanosoma rangeli is reported in this study for the first time. METHODS The triatomines were collected from the campus of the Federal University of Acre in Rio Branco, Acre, Brazil. The identification of T. rangeli was confirmed by multiplex polymerase chain reaction. RESULTS The examinations of two specimens revealed R. stali infection by the epimastigote forms of T. rangeli. CONCLUSIONS The encounter of R. stali infected by T. rangeli generates an alert for the state of Acre, since the simultaneous presence with Trypanosoma cruzi can make the differential diagnosis of Chagas disease difficult.

Resumen Introducción. Trypanosoma cruzi se ha dividido en seis unidades taxonómicas discretas (Discreet Typing Units, DTU) denominadas TcI, TcII, TcIII, TcIV, TcV y TcVI. Aún se desconocen los factores determinantes de la dinámica de la transmisión vectorial de los genotipos de T. cruzi en las diferentes regiones geográficas de distribución de la enfermedad de Chagas en Perú. Objetivo. Detectar y tipificar las unidades taxonómicas discretas de T. cruzi en las heces de siete especies de triatominos (Panstrongylus chinai, P. geniculatus, P. herreri, Rhodnius robustus, R. pictipes, Triatoma carrioni y T. infestans), capturados en ocho departamentos de diferentes regiones naturales de Perú. Materiales y métodos. Se examinaron 197 insectos para la detección de tripanosomas. Se extrajo el ADN del contenido intestinal de cada insecto y se amplificó mediante reacción en cadena de la polimerasa (PCR) de los genes kDNA, SL-IR, 24Sa rRNA y 18Sa RNA para detectar las DTU de T. cruzi. Resultados. Se detectaron cinco infecciones con T. rangeli y 113 con T. cruzi. De estas últimas, fue posible identificar 95 de TcI (dos en P. chinai, una en P. geniculatus, 68 en P. herreri, cuatro en R. pictipes, siete en R. robustus, una en T. carrioni, y 12 en T. infestans); cinco de TcII (cuatro en P. herreri, una en T. infestans); cuatro de TcIII (tres en P. herreri, una en R. robustus) y cuatro infecciones de TcIV en P. herreri. Conclusión. Este es el primer trabajo de caracterización a gran escala de T. cruzi en el intestino de vectores de importancia epidemiológica en Perú, orientado a generar información básica que permita entender la dinámica de la transmisión vectorial de T. cruzi en esta región del continente.

Abstract Introduction: Trypanosoma cruzi has been divided by international consensus into six discrete typing units (DTU): TcI, TcII, TcIII, TcIV, TcV y TcVI. The factors determining the dynamics of T. cruzi genotypes vector transmission of Chagas’ disease in the different geographical regions of Perú are still unknown. Objective: To detect and type T. cruzi DTUs from the faeces of seven species of triatomines (Panstrongylus chinai, P. geniculatus, P. herreri, Rhodnius robustus, R. pictipes, Triatoma carrioni and T. infestans) captured in eight departments from different natural regions of Perú. Materials and methods: We examined 197 insects for detecting trypanosomes. DNA was extracted from each insect intestinal contents and PCR amplification of kDNA, SL-IR, 24Sa rRNA and 18Sa RNAwas performed for detecting T. cruzi DTUs. Results: Five T. rangeli and 113 T. cruzi infections were detected; 95 of the latter were identified as TcI (two in P. chinai, one in P. geniculatus, 68 in P. herreri, four in R. pictipes, seven in R. robustus, one in T. carrioni, 12 in T. infestans), five as TcII (four in P. herreri, one in T. infestans), four as TcIII (three in P. herreri, one in R. robustus) and four TcIV infections in P. herreri. Conclusions: This is the first study which has attempted a large-scale characterization of T. cruzi found in the intestine of epidemiologically important vectors in Perú, thus providing basic information that will facilitate a better understanding of the dynamics of T. cruzi vector transmission in Perú.

ABSTRACT Trypanosomatid type I nitroreductases (NTRs), i.e., mitochondrial enzymes that metabolise nitroaromatic pro-drugs, are essential for parasite growth, infection, and survival. Here, a type I NTR of non-virulent protozoan Trypanosoma rangeli is described and compared to those of other trypanosomatids. The NTR gene was isolated from KP1(+) and KP1(-) strains, and its corresponding transcript and 5’ untranslated region (5’UTR) were determined. Bioinformatics analyses and nitro-drug activation assays were also performed. The results indicated that the type I NTR gene is present in both KP1(-) and KP1(+) strains, with 98% identity. However, the predicted subcellular localisation of the protein differed among the strains (predicted as mitochondrial in the KP1(+) strain). Comparisons of the domains and 3D structures of the NTRs with those of orthologs demonstrated that the nitroreductase domain of T. rangeli NTR is conserved across all the strains, including the residues involved in the interaction with the FMN cofactor and in the tertiary structure characteristics of this oxidoreductase protein family. mRNA processing and expression were also observed. In addition, T. rangeli was shown to be sensitive to benznidazole and nifurtimox in a concentration-dependent manner. In summary, T. rangeli appears to have a newly discovered functional type I NTR.

Abstract: INTRODUCTION: Behavioral fever is a response to infections with microorganisms observed in some poikilothermic animals. Rhodnius prolixus is involved in the transmission of two parasites: Trypanosoma cruzi (pathogenic for humans and transmitted in feces) and Trypanosoma rangeli (non-pathogenic for humans, pathogenic for Rhodnius and transmitted by the bite of an infected individual). Only T. rangeli is found in the hemolymph of Rhodnius as it travels to the salivary glands. METHODS: To study vector-parasite interactions, we evaluated possible behavioral fever responses of R. prolixus to intracoelomic inoculation with T. cruzi or T. rangeli. Temperature preferences of fifth-instar nymphs of R. prolixus were evaluated after inoculation with T. rangeli KP1(+), KP1(-), T. cruzi I, or the Trypanosome culture medium. Four different fixed temperatures (25, 30, 35, and 40°C) in two simultaneous experiments (enclosed and free-moving insects) were evaluated. Free-moving insects were marked daily according to their temperature preferences on each of the 15 days after inoculation. Numbers of insects in each temperature shelter and daily mortality were compared with those enclosed shelters of different temperatures. RESULTS: Rhodnius prolixus inoculated with both strains of T. rangeli and with the trypanosome culture medium showed preferences for the lowest temperatures (25°C). However, R. prolixus inoculated with T. cruzi I showed significant preferences for temperatures around 35°C. CONCLUSIONS: This is the first known investigation to demonstrate a behavioral fever response in R. prolixus injected intracoelomically with T. cruzi I.

Abstract: INTRODUCTION This work shows that 3% (v/v) human urine (HU) in semisolid Liver Infusion Tryptose (SSL) medium favors the growth of Trypanosoma cruzi and T. rangeli. METHODS Parasites were plated as individual or mixed strains on SSL medium and on SSL medium with 3% human urine (SSL-HU). Isolate DNA was analyzed using polymerase chain reaction (PCR) and pulsed-field gel electrophoresis (PFGE). RESULTS SSL-HU medium improved clone isolation. PCR revealed that T. cruzi strains predominate on mixed-strain plates. PFGE confirmed that isolated parasites share the same molecular karyotype as parental cell lines. CONCLUSIONS SSL-HU medium constitutes a novel tool for obtaining T. cruzi and T. rangeli clonal lineages.

Dogs play a major role in the domestic cycle of Trypanosoma cruzi, acting as reservoirs. In a previous work we have developed a model of vaccination of dogs in captivity with nonpathogenic Trypanosoma rangeli epimastigotes, resulting in the production of protective antibodies against T. cruzi, with dramatic decrease of parasitaemia upon challenge with 100,000 virulent forms of this parasite. The aim of this work was to evaluate the immunogenicity of this vaccine in dogs living in a rural area. Domestic dogs, free from T. cruziinfection, received three immunisations with fixed T. rangeliepimastigotes. Dogs were not challenged with T. cruzi, but they were left in their environment. This immunisation induced antibodies againstT. cruzi for more than three years in dogs in their natural habitat, while control dogs remained serologically negative.

A diferencia de Trypanosoma cruzi, agente causal de la enfermedad de Chagas, Trypanosoma rangeli es un parásito infectivo y no patógeno para el humano, pero sí para los vectores del género Rhodnius. Con base en polimorfismos del ADN del cinetoplasto (kADN), del gen miniexón o líder de empalme (Spliced Leader), del espaciador interno transcrito (ITS) y de la subunidad pequeña del ribosoma (SSU rARN), se han descrito varios genotipos de T. rangeli (KP1+/A, B, KP1-/C, KP1-/D y E), los cuales son transmitidos selectivamente por dos líneas filogenéticas de Rhodnius, lo que indica la ocurrencia de procesos coevolutivos entre el parásito y los vectores. La línea Robustus (Rhodnius prolixus, Rhodnius robustus y Rhodnius neglectus) transmite exclusivamente el genotipo KP1+/A y la línea Pallescens (Rhodnius pallescens, Rhodnius colombiensis y Rhodnius ecuadoriensis) transmite el genotipo KP1-/C. Aunque el conocimiento de las bases moleculares de la interacción parásito-vector es todavía escaso, este trabajo presenta observaciones inéditas sobre la capacidad de los genotipos KP1+/A y KP1-/C para completar el ciclo de vida en algunas de las 19 especies de Rhodnius y la detección de factores tripanolíticos en R. prolixus, R. robustus y R. neglectus contra el genotipo KP1-/C y varios genotipos de T. cruzi. Los avances recientes en los estudios de transcripción genómica de T. rangeli, y su comparación con T. cruzi constituyen el punto de partida para entender cabalmente la transmisión vectorial selectiva de T. rangeli y T. cruzi, así como de la patogenia de T. rangeli para el vector y de la incapacidad de T. rangeli y la capacidad de T. cruzi para invadir células del mamífero.

Unlike Trypanosoma cruzi, the causative agent of Chagas' disease, T. rangeli is an infective, non-pathogenic parasite for humans, but pathogenic for vectors from the Rhodnius genus. Several T. rangeli genotypes (KP1+/A, B, KP1-/C, KP1-/D and E) have been described based on kinetoplast DNA (kDNA) polymorphisms, the spliced leader or miniexon, the intergenic transcribed spacer (ITS) and the small ribosomal subunit (SSUrRNA). These are selectively transmitted by two Rhodnius phylogenetic lines, thereby indicating co-evolutionary processes between parasite and vector genotypes. The Robustus line (Rhodnius prolixus, R. robustus and R. neglectus) exclusively transmits the KP1+/A genotype and the Pallescens line (R. pallescens, R. colombiensis and R. ecuadoriensis) only transmits the KP1-/C genotype. Even though little knowledge is available regarding the molecular basis of parasite- vector interaction, the present work presents unpublished observations about KP1+/A and KP1-/C genotype ability to complete the life-cycle of some of the 19 Rhodnius species and the detection of trypanolytic factors in R. prolixus, R. robustus and R. neglectus against the KP1-/C genotype and some T. cruzi genotypes. Several advances regarding molecular, transcriptome and genomic studies dealing with T. rangeli are presented and compared to T. cruzi; these are the starting point for understanding the selective vectorial transmission of T. rangeli and T. cruzi, T. rangeli pathogenicity for the vector, as well as T. rangeli inability and T. cruzi ability to invade mammalian cells.

Introducción. Se han detectado asociaciones biológicas huésped-parásito específicas que sugieren que los triatominos del género Rhodnius podrían actuar como filtros biológicos en la transmisión de Trypanosoma rangeli . Objetivo. Estudiar la sensibilidad de cuatro especies de Rhodnius ( Rhodnius robustus , Rhodnius neglectus , Rhodnius nasutus y Rhodnius p ictipes ) frente a la cepa de T. rangeli (SC-58/KP1-). Materiales y métodos. Se seleccionaron treinta ninfas de cada especie después de xenodiagnóstico artificial en sangre infectada con T. rangeli. Se examinaron periódicamente m uestras de heces y hemolinfa. Los insectos con hemolinfas infectadas fueron alimentados en ratones a fin de comprobar la transmisión por picadura y posteriormente disecados para confirmar la infección de las glándulas salivales . Resultados . En Rhodnius pictipes se encontró un mayor porcentaje de infección intestinal que en las otras especies . Se detectaron epimastigotes y tripomastigotes en la hemolinfa de las cuatro especies , y se encontró que el parasitismo fue menor en las especies del linaje R. robustus . Rhodnius robustus y R. neglectus no transmitían T. rangeli a ratones por picadura: después de la disección , sus glándulas no estaban infectadas. Solo un espécimen de R. nasutus y dos de R. pictipes transmitieron el parásito por la picadura . La tasa de infección glandular fue de 16 % para R. pictipes y de 4 % para R. nasutus . Conclusiones . La capacidad infecciosa ( hemolinfática, intestinal y glandular ) y la transmisión de T. rangeli (SC-58/KP1-) fueron mayores y más eficientes en R. pictipes . Estos resultados refuerzan la hipótesis de que estos triatominos actúan como filtros biológicos en la transmisión de T. rangeli .

Introduction: Specific host-parasite a ssociations have been detected experimentally and suggest that triatomines of the genus Rhodnius act as biological filters in the transmission of Trypanosoma rangeli . Objective: To analyze the susceptibility of four Rhodnius species ( Rhodnius robustus , Rhodnius neglectus , Rhodnius nasutus and Rhodnius pictipes ) to a Brazilian strain of T. rangeli (SC-58/KP1-). Materials and methods: We selected t hirty nymphs of each species, which were fed on blood infected with T. rangeli . Periodically, samples of feces and hemolymph were analyzed. Triatomines with T. rangeli in their hemolymph were fed on mice to check for transmission by bites. Later, the triatomines were dissected to confirm salivary gland infection. Results: Specimens of R. pictipes showed higher rates of intestinal infection compared to the other three species. Epimastigotes and trypomastigotes were detected in hemolymph of four species; however, parasitism was lower in the species of the R. robustus lineage. Rhodnius robustus and R. neglectus specimens did not transmit T. rangeli by bite; after dissection, their glands were not infected. Only one specimen of R. nasutus and two of R. pictipes transmitted the parasite by bite. The rate of salivary gland infection was 16% for R. pictipes and 4% for R. nasutus . Conclusions: Both infectivity (intestinal, hemolymphatic and glandular) and transmission of T. rangeli (SC58/KP1-) were greater and more efficient in R. pictipes. These results reinforce the hypothesis that these triatomines may act as biological filters in the transmission of T. rangeli .

Os triatomíneos são insetos hematófagos que apresentam interesse médico nas América do Sul e Central por serem hospedeiros invertebrados dos protozoários hemoflagelados Trypanosoma cruzi (agente etiológico da doença de Chagas) e Trypanosoma rangeli (Tejera, 1920). Os triatomíneos do gênero Rhodnius possuem glândula salivar formada por duas unidades próximas e independentes: a principal e a acessória. Esta glândula secreta uma saliva que contém substâncias que facilitam e permitem a hematofagia. Entretanto, apesar da sua importância, poucos estudos realizaram sua análise citoquímica. No propósito de ampliar esse entendimento, neste trabalho foram investigadas as estruturas nucleares (cromatina e corpúsculos nucleolares) das células da glândula salivar de Rhodnius neglectus (Lent, 1954) e Rhodnius prolixus (Stål, 1859). As glândulas foram removidas de insetos adultos, fixadas e submetidas a diferentes métodos citoquímicos: Orceína Lacto-Acética, Impregnação por Íons de Prata, Reação de Feulgen, Azul de Toluidina, Variante da Concentração Eletrolítica Crítica e Bandamento C. Os resultados evidenciaram predomínio de células binucleadas, com núcleos volumosos e poliplóides, cromatina descondensada e uma grande área nucleolar. Além disso, foi observada metacromasia citoplasmática e uma clara associação entre os corpúsculos nucleolares e heterocromáticos. Tais características foram associadas às atividades de intensa síntese proteica para a produção de saliva. Além disso, os corpúsculos heterocromáticos observados no Bandamento C permitiram a diferenciação dos sexos e das espécies.

Triatomines are hematophagous bugs of medical interest in South and Central America, where they may act as invertebrate hosts of the hemoflagellate protozoa Trypanosoma cruzi (the causative of Chagas’ disease) and Trypanosoma rangeli (Tejera, 1920). Triatomines of Rhodnius genus have salivary gland formed by two close and independent units: the principal and the accessory. This gland secretes saliva that abounds in substances that facilitate and permit feeding. Despite this importance, there are few reports on its cytochemistry. In purpose of amplifying this understanding, in this work it was investigated the nuclear structures (chromatin and nucleolar corpuscles) of salivary gland cells of Rhodnius neglectus (Lent, 1954) and Rhodnius prolixus (Stål, 1859). The salivary glands were removed from adult insects, fixed and submitted to different cytochemical methods: lacto-acetic orcein, silver ion impregnation, Feulgen reaction, Toluidine Blue, Variant method of critical electrolyte concentration and C-banding. The results evidenced predominance of binucleated cells, with bulky and polyploid nucleus, decondensed chromatin and a large nucleolar area. In addition, cytoplasmic metachromasy and a clear association between nucleolar and heterochromatic corpuscles were observed. Such characteristics were associated with intense synthesis activity to produce saliva. Besides, the heterochromatic corpuscles observed with C Banding permitted the differentiation of sexes and species.

Introduction: This study reports for the first time the infection of Rhodnius montenegrensis by Trypanosoma rangeli. Methods: The triatomines were manually collected in Attalea speciosa in the municipality of Buritis, Rondônia. The identification of the trypanosomatid species was confirmed by multiplex PCR. Results: All of the collected triatomines were R. montenegrensis. The analysis confirmed that all of the adults were infected with the epimastigote form of T. rangeli. Conclusions: This report of a new vector of T. rangeli raises a warning for the State of Rondônia because the simultaneous presence of T. rangeli with T. cruzi in the same geographic region enables the occurrence of mixed infections in hosts and vectors, which complicates the differential diagnosis.

In this study the effect of eight DNA topoisomerase inhibitors on the growth Trypanosoma rangeli epimastigotes in cell culture was investigated. Among the eight compounds tested, idarubicin was the only compound that displayed promising trypanocidal activity with a half-maximal growth inhibition (GI50) value in the sub-micromolar range. Fluorescence-activated cell sorting analysis showed a reduction in DNA content in T. rangeli epimastigotes when treated with idarubicin. In contrast to T. rangeli, against Trypanosoma cruzi epimastigotes idarubicin was much less effective exhibiting a GI50 value in the mid-micromolar range. This result indicates that idarubicin displays differential toxic effects in T. rangeli and T. cruzi. Compared with African trypanosomes, it seems that American trypanosomes are generally less susceptible to DNA topoisomerase inhibitors.