Trypanosoma cruzi pathogenesis and histotropism: don ́t forget analizing DTU and parasite populations when studying the infection

JUAN M. BURGOS

Mar del Plata

Congreso; XXXI Reunión Anual Sociedad Argentina de Protozoología; 2019

Chagas disease, caused by Trypanosoma cruzi, is one of the most important parasitic infection in America. With a prevalence of about 8 million people, it primarily affects rural populations but also migrant ones in Americas´ cities and all around the world. Pathological outcomes ranges from subclinical infection to cardiac and digestive syndromes, SNC affection, and death. In 2009 six Discrete Typing Units (DTU) were define into the specie, where each group is identifiable by common molecular markers and constitute reliable units for molecular epidemiology and evolution analysis. Different approaches, alone or in combination, are well accepted to determine parasite DTUs. PCR amplification of multicopy polymorphic sequences (SL intergenic region, 24Sα rDNA, 18S rDNA, the A10 fragment), PCR-RFLP of genes (HSP60, GPI, COII, TcSC5D, TcMK), or DNA sequencing (kDNA, TcSC5D) are used to determine T. cruzi DTUs, while other strategies (e.g. kDNA-PCR-RFLP) allow intra-DTU parasite populations comparison. With very different prevalences along the continent, all DTUs are observe in human infections. Although the association between them and the evolution of the infection and pathogenia development is still uncertain, researches information collection along years allowed observe the presence of behaviors that demand the DTU and intra-DTU analysis for a better comprehension of it. Clonal histotropism, differential virulence and response against drugs are some of the phenomenon observed. In this sense blood parasites, easily characterizable, may not be related to those populations damaging tissues. Moreover, for accuracy parasite quantification by real time PCR, DTU identity should be determined due to different genetic burden among them. Complexity of natural infections, usually multiclonal, besides host genetic background make the truly understanding of the infection and its evolution a challenge, where the parasite DTU determination is an important piece in the disease jigsaw.