Drug-resistant epimastigotes of Trypanosoma cruzi and persistence of this phenotype after differentiation into amastigotes

Des formes épimastigotes du parasite #Trypanosoma cruzi ont été rendues résistantes au benznidazole en utilisant, in vitro, une pression médicamenteuse continue. Les parasites ont été sélectionnés en fonction de la caractérisation génétique antérieure de leurs loci isoenzymatiques. Tous les clones résistants sont capables de croître en culture à long terme en présence d'une concentration d'au moins 50 microM de benznidazole qui est la dose circulante de drogue chez un patient en cours de traitement. Le niveau le plus élevé de résistance atteint est 220 microM. Après la différenciation des formes épimastigotes en amastigotes, le niveau de résistance n'est pas altéré. La vitesse de croissance des formes résistantes d'épimastigotes et d'amastigotes est inférieure à celle des formes sauvages mais leur viabilité n'est pas affectée. Ces résultats peuvent avoir des conséquences à la fois pour entreprendre l'étude du phénotype résistant de clones du parasite #T. cruzi mais également pour suivre le devenir de ce phénotype résistant au cours du développement du cycle expérimental in vivo. (Résumé d'auteur

Blood meal sources of wild and domestic Triatoma infestans (Hemiptera : Reduviidae) in Bolivia : connectivity between cycles of transmission of Trypanosoma cruzi

Background: Chagas disease is a major public health problem in Latin America. Its etiologic agent, Trypanosoma cruzi, is mainly transmitted through the contaminated faeces of blood-sucking insects called triatomines. Triatoma infestans is the main vector in various countries in South America and recently, several foci of wild populations of this species have been described in Bolivia and other countries. These wild populations are suspected of affecting the success of insecticide control campaigns being carried out in South America. To assess the risk that these T. infestans populations pose to human health, it is helpful to determine blood meal sources. Methods: In the present work, blood meals were identified in various Bolivian wild T. infestans populations and in three specific areas, in both wild and intra-peridomestic populations to assess the links between wild and domestic cycles of T. cruzi transmission. PCR-HDA and sequencing of Cytb gene were used to identify these blood meal sources. Results and discussion: Fourteen vertebrate species were identified as wild blood meal sources. Of those, the most prevalent species were two Andean endemic rodents, Octodontomys gliroides (36 %) and Galea musteloides (30 %), while humans were the third most prevalent source (18.7 %). Of 163 blood meals from peridomestic areas, more than half were chickens, and the others were generally domestic animals or humans. Interestingly, blood from wild animals was identified in triatomines captured in the peridomestic and domestic environment, and blood from domestic animals was found in triatomines captured in the wild, revealing links between wild and domestic cycles of T. cruzi transmission. Conclusion: The current study suggests that wild T. infestans attack humans in the wild, but is also able to bite humans in domestic settings before going back to its natural environment. These results support the risk to human health posed by wild populations of T. infestans

Molecular Typing of Trypanosoma cruzi Isolates, United States

Studies have characterized Trypanosoma cruzi from parasite-endemic regions. With new human cases, increasing numbers of veterinary cases, and influx of potentially infected immigrants, understanding the ecology of this organism in the United States is imperative. We used a classic typing scheme to determine the lineage of 107 isolates from various hosts

Metabarcoding: A Powerful Yet Still Underestimated Approach for the Comprehensive Study of Vector-Borne Pathogen Transmission Cycles and Their Dynamics

The implementation of sustainable control strategies aimed at disrupting the transmission of vector-borne pathogens requires a comprehensive knowledge of the vector ecology in the different eco-epidemiological contexts, as well as the local pathogen transmission cycles and their dynamics. However, even when focusing only on one specific vector-borne disease, achieving this knowledge is highly challenging, as the pathogen may exhibit a high genetic diversity and multiple vector species or subspecies and host species may be involved. In addition, the development of the pathogen and the vectorial capacity of the vectors may be affected by their midgut and/or salivary gland microbiome. The recent advent of Next-Generation Sequencing (NGS) technologies has brought powerful tools that can allow for the simultaneous identification of all these essential components, although their potential is only just starting to be realized. We present a metabarcoding approach that can facilitate the description of comprehensive host-pathogen networks, integrate important microbiome and coinfection data, identify at-risk situations, and disentangle the transmission cycles of vector-borne pathogens. This powerful approach should be generalized to unravel the transmission cycles of any pathogen and their dynamics, which in turn will help the design and implementation of sustainable, effective, and locally adapted control strategies

Scarce events of mitochondrial introgression in Trypanosoma cruzi : new case with a Bolivian strain

Ttypanosoma cruzi, the agent of Chagas disease, presents a predominantly clonal structure that has been shaped by recombination events leading to six genetic groups (DTUs, discrete typing units, Tcl-TcVI). Several conventional and unconventional genetic exchange events have been described, including hybridization and mitochondrial introgression, which is explored here among Eolivian and Peruvian strains belonging to TcI because recombination events have been previously suspected by means of the MLMT method (multilocus microsatellite typing). We analyzed the variation of one nuclear (Gpi) and one mitochondrial (Nd1) gene among 60 TcI strains and 15 reference strain belonging to the six DTUs. The results clearly showed that one strain isolated from Triatoma infestans in the Cochabamba department (Bolivia) presented a genotype TcI for Gpi and a mitochondrial Nd1 genotype common to the DTUs Tat IV, V. and VI; this can be interpreted as a mitochondrial introgression event between distant DTUs. These kinds of events, although probably scarce, may have played an important role in the adaptive evolution of the species