Identificação e análise filogenética de Trypanosoma cruzi detectados em Triatoma brasiliensis (Hemiptera: Reduviidae: Triatominae) capturados em diferentes municípios do Rio Grande do Norte

Abstract

Ribosomal DNA (rDNA) consists of genes used as molecular markers in the identification of trypanosomatids and show good results. The most used sequences for this aim correspond to its Small Subunit (SSU). In this work, the Trypanosoma cruzi 18S rRNA gene was amplified by Nested-PCR for the identification of Discrete Typing Units (DTUs) and phylogenetic analysis of parasite isolates, which were obtained from samples of the intestinal contents of Triatoma brasiliensis triatomines with previously known natural infection. Specimens were captured in nine municipalities in the Agreste, Central and West mesoregions of the state of Rio Grande do Norte (RN) in a previous study. Sequences of this gene were amplified with ~780 base pairs (bp) in 43.24% (16/37) of the samples. The samples ACA 23Tb, ACA 28Tb, CA 100-102Tb, CA 103Tb and Tb2 C Santa Rosa Acari went to Sanger sequencing and the quality of the process was observed in its electropherograms. The generated sequences went to alignments with GenBank sequences, by the BLASTN tool. Identity values greater than 90% were obtained with T. cruzi sequences from the database. The consensus sequences of samples CA 100-102Tb, ACA 28Tb and Tb2 C Santa Rosa Acari were used to generate Maximum Likelihood (MV) and Bayesian Inference (IB) phylogenetic trees with sequences of T. cruzi strains, corresponding to the DTUs I to VI, and Trypanosoma rangeli and Blastocrithidia triatomae (outgroups), from Genbank for the inference of a phylogenetic relationship between them. The results of preliminary analyses, identification and phylogenetic analysis confirmed CA 100-102Tb sample as DTU I and ACA 28Tb and Tb2 C Santa Rosa Acari samples as DTU II, indicating that these DTUs remain circulating in the domiciliary and peridomiciliary cycles in the RN, corroborating the importance of T. brasiliensis as a vector of T. cruzi in the state.