the agent of Chagas disease is a monophyletic but heterogeneous group conformed by several Discrete Typing Units (DTUs) named TcI to TcVI characterized by genetic markers. TcBat has been added [3], [4]. Because of the predominantly clonal evolution of the parasite, these DTUs are rather stable in space and time, constituting a useful framework for epidemiological and IC-83 evolutionary analysis [5]. This genetic diversity seems to be correlated with a geographical distribution [3], [6],[7] and with biological characteristics of the parasite such as culture growth, pathogenicity in mice, evolution in the insect IC-83 vector, susceptibility to antichagasic drugs and tissular tropism in animal and human infections. Human contamination displays different IC-83 clinical evolutions ranging from asymptomatic to cardiomyopathy, megaviscera or even death. Different outcome incidences are also determined by host genetics, the presence of mixed infections, cultural factors, etc. [8]. Within the endemic area, heterogeneous geographical distribution of DTUs has been extensively described suggesting that this genetic composition of the parasite could be partly responsible for the different manifestations of Chagas disease. Broadly, TcI is found from the south of the USA in the sylvatic environment to northern South America Rabbit Polyclonal to IRF4. where it seems to be responsible for chagasic cardiomyopathy [7], [9]C[11]. In Southern Cone countries, TcI is usually associated to the sylvatic cycle whereas TcII, TcV, and TcVI are relatively more abundant than TcI in the domestic cycle [3], [12], [13]. In this region, human infections present higher rates of severe heart affectation [7], [14]C[18] and digestive abnormalities, which are outstanding in northern South America and Central America [19], [20]. TcIII which is usually isolated from vectors and sylvatic reservoirs has a low prevalence in human infections [11], [21], [22] whereas TcIV shows a similar geographical distribution but higher incidence in human contamination [15], [23]C[25]. Although sialic acid is crucial for the life cycle of iTS deduced amino acid sequences shows variations in 20 residues, although the inactivation is entirely due to the single crucial Tyr342His usually replacement as a consequence of a T/C transition [33]. The replacement by histidine renders the protein enzymatically inactive but allows retaining the substrate binding ability conferring therefore a lectin-like activity [32], [34]. This strongly suggests a physiologic role for iTS in parasite attachment to substrates or cell surface receptors that might explain its conservation. Crystallographic analyses and enzyme kinetic assays [35] have recently shown that iTS retains residual hydrolytic activity. By using the recombinant iTS, a co-stimulating host T-cells effect have been adscribed [36]. Previous efforts to associate parasite genetic classification and biological features have allowed us to determine the expression/shed of aTS as a marker of pathogenicity that segregates strains belonging to different lineages [37]. In this study our aim was to analyze the distribution of genes encoding the virulence factor TS among DTU-representative isolates collected along the Americas in the context of their evolution. We found in all analyzed stocks and the striking absence of genes in TcI, TcIII and TcIV DTUs. The consistence of IC-83 the TS results with current evolutionary genome models was reviewed to fit findings. Parasite stocks to attempt genetic KO or to assay the involvement of iTS in parasite biology and virulence are now available. Materials and Methods Trypanosoma cruzi isolates The study was carried out in a panel of 38 parasite isolates encompassing IC-83 all DTUs (nine TcI stocks, seven TcII, two TcIII, five TcIV, six TcV, and nine TcVI) obtained from various ecological origins (vectors, animal reservoirs and human infections) spanning all the endemic area from Argentina to the USA. genomic DNA purification DNA from Ac, Hc, K-98, SN, Br, CMA, ChVal, HE, HT, RA, Q501/3, Tulahuen, ML, Alf, FAL and Cvd parasite strains was obtained from peripheral blood trypomastigotes. DNA from Silvio X10, Tu18, M5631, Can III, CL Brener, CID, H1, QUE, CBBcl2, ESMcl3Z2, IVVcl4, MAS1cl1, MVBcl8, X109/2, 3.1, 92122102R, STC10R, STC16Rcl1, MNcl2, SC43cl1, CA15, P63cl1 strains was obtained from epimastigotes. The Blood and Cell Culture DNA Purification Kit (Qiagen) or conventional phenol-chloroform DNA extraction methods were used. DTU characterization All DNA samples were genotyped using polymerase chain reaction (PCR) strategies following Burgos et al [17].