Association between Trypanosoma cruzi DTU TcII and chronic Chagas disease clinical presentation and outcome in an urban cohort in Brazil.

BACKGROUND: The specific roles of parasite characteristics and immunological factors of the host in Chagas disease progression and prognosis are still under debate. Trypanosoma cruzi genotype may be an important determinant of the clinical chronic Chagas disease form and prognosis. This study aimed to identify the potential association between T. cruzi genotypes and the clinical presentations of chronic Chagas disease. METHODOLOGY/PRINCIPAL FINDINGS: This is a retrospective study using T. cruzi isolated from blood culture samples of 43 patients with chronic Chagas disease. From 43 patients, 42 were born in Brazil, mainly in Southeast and Northeast Brazilian regions, and one patient was born in Bolivia. Their mean age at the time of blood collection was 52.4±13.2 years. The clinical presentation was as follows 51.1% cardiac form, 25.6% indeterminate form, and 23.3% cardiodigestive form. Discrete typing unit (DTU) was determined by multilocus conventional PCR. TcII (n = 40) and TcVI (n = 2) were the DTUs identified. DTU was unidentifiable in one patient. The average follow-up time after blood culture was 5.7±4.4 years. A total of 14 patients (32.5%) died and one patient underwent heart transplantation. The cause of death was sudden cardiac arrest in six patients, heart failure in five patients, not related to Chagas disease in one patient, and ignored in two patients. A total of 8 patients (18.6%) progressed, all of them within the cardiac or cardiodigestive forms. CONCLUSIONS/SIGNIFICANCE: TcII was the main T. cruzi DTU identified in chronic Chagas disease Brazilian patients (92.9%) with either cardiac, indeterminate or cardiodigestive forms, born at Southeast and Northeast regions. Other DTU found in much less frequency was TcVI (4.8%). TcII was also associated to patients that evolved with heart failure or sudden cardiac arrest, the two most common and ominous consequences of the cardiac form of Chagas disease.

Infecção natural de Triatoma brasiliensis brasiliensis, Caicó, Rio Grande do Norte, pelo Trypanosoma cruzi e o estudo de peptídeos antimicrobianos em diferentes espécies de triatomíneos (Hemiptera, Heteroptera, Reduviidae) / Natural infection of Triatoma brasiliensis brasiliensis, Caicó, Rio Grande do Norte by trrypanosoma cruzi and the study of antimicrobial peptides in different triatomine species (hemiptera, heteroptera, reduviidae)

Triatoma brasiliensis é um dos vetores da doença de Chagas no Nordeste do Brasil, apresentando altos índices de infecção natural pelo Trypanosoma cruzi. No presente estudo, dois aspectos foram abordados: primeiro a coleta de exemplares de T. b. brasiliensis oriundos de Caicó, RN, para análise de infecção natural por T. cruzi, em períodos diferentes (abril e novembro de 2011). O segundo aspecto abordado está relacionado ao estudo do gene que codifica defensinas como marcador molecular filogenético para a análise de diferentes espécies de triatomíneos, incluindo o complexo T. brasiliensis, além de exemplares de T. b. brasiliensis coletados em Caicó. Em relação à infecção natural de T. b. brasiliensis por T. cruzi observamos um alto índice (86 porcento), mais especificamente na localidade de Penedo. Também foi observado que não houve diferenças significativas entre as expedições realizadas nos períodos de chuva (abril de 2011) e seca (novembro de 2011)Além disso, cinco isolados de T. cruzi foram caracterizados molecularmente por duas metodologias: mini-exon, 24Salpha rDNA e 18S rDNA. Como resultados observamos os dois genótipos (TcI e TcII) circulando em Caicó. Foram obtidas sequências do gene que codifica defensina, onde diferentes isoformas deste gene puderam ser identificadas e caracterizadas nas diferentes espécies de triatomíneos estudadas. A espécie Panstrongylus megistus ficou nos mesmos clados que representantes do gênero Rhodnius. Houve uma clara separação dos clados em relação aos gêneros Triatoma e Rhodnius. Com relação aos membros do complexo T. brasiliensis, não foi possível uma clara distinção entre as espécies pelo fato da molécula de defensina apresentar menos que 500 bp em seu tamanho, além de ser bastante conservada, não sendo portanto um bom marcador para separar grupos muito proximamente relacionados...

Triatoma brasiliensis is one of the main Chagas disease vectors in NortheasternBrazil, presenting a high natural Trypanosoma cruzi infection rate. In the present work, two different aspects were investigated: First, triatomines of the subspecies T. b. brasiliensis were collected in Caicó, RN for analysis of natural infection by T. cruzi in two dissimilar periods (April and November 2011). The second aspect is related touse of defensin encoding genes as a phylogenetic marker for the study of different triatomine species, mainly the T. brasiliensis species complex, including T. b. brasiliensis specimens from Caicó. The results showed a high infection rate (86 percent) of T. b. brasiliensis from Caicó by T. cruzi, especially in insects from Penedo. Nosignificant differences between the rainy period (April 2011) and dried season (November 2011) could be observed. In addition, five T. cruzi isolates were cultivated and characterized by three different molecular methods (mini-exon, 24Salpha rDNA and 18S rDNA). The results showed the presence of TcI and TcII genotypes circulating in Caicó. Defensin encoding genes were amplified and sequenced for different triatomine species, showing three differing forms. Panstrongylus megistus clusteredtogether with representatives of the genus Rhodnius. A separation between the genus Triatoma and Rhodnius could also be detected. However, inside of the T. brasiliensis species complex the taxa could not be well separated. Since thismolecular marker has a size of less than 500 bp and is highly conserved defensinencoding sequences might not be a good marker to separate closely related species and subspecies...