Trypanosoma cruzi:Impact of Clonal Evolution of the Parasite on Its Biological and Medical Properties

Trypanosoma cruzi: clonal structure of parasite strains and the importance of principal clones

“…Correlations between the sensibility to benznidazole and nifurtimox and the genetic distances of T. cruzi stocks, have been described by Revollo et al (1998). This is in agreement with the observation that resistance to chemotherapy is related to the biological characteristics of the T. cruzi strains .…”

“…According to those authors, T. cruzi strains are natural clones and the natural selection, favouring only certain genetic pattern or combinations, could account for a limited number of isoenzyme strains, represented by three major clones. By using several parameters in vitro, Revollo et al (1998) has confirmed the hypothesis of a correlation between biological and phylogenetic variability of T. cruzi, by multilocus enzyme electrophoresis (MLEE), and random amplification of polymorphic DNA (RAPD), based on the genetic distances. Biological types (biodemes), are correlated with the zymodemes which were described by Miles et al (1980), with the exception of the Type I strain that presented a peculiar electrophoretic profil not described previously (Andrade et al 1983) and that has been subsequently identified as Z2b; biodeme Type II corresponds to Z2, and Type III, to Z1.…”

Update on Chagas' disease in Mexico

“…However, the relationship between genotypes and biological characteristics such as infectivity and virulence is still debated and not clearly understood. [57][58][59] The direct assessment of infectivity and virulence of Mexican strains in vitro and in vivo also indicated an important variability between strains, but their overall virulence appears comparable to that found in strains from other regions [55][56] Barrera-Perez, unpublished results). These observations appear to point out the existence of T. cruzi strains in Mexico well able to induce chronic chagasic cardiomyopathy.…”

Usefulness of PCR-based assays to assess drug efficacy in Chagas disease chemotherapy: value and limitations

“…Moreover, this parasite undergoes long-term clonal evolution that predicts correlation among phylogenetic divergence. The parasite's biological properties play an important role in the disease pathogenesis (morbidity) and may affect drug efficacy (Andrade et al 1975, Tibayrenc et al 1986, Andrade & Magalhães 1996, Revollo et al 1998, Toledo et al 2003. The occurrence of naturally resistant T. cruzi strains demonstrated in experimental models (Filardi & Brener 1987, Murta et al 2008) is supposed to be one of the most important factors explaining the low rates of cure in some treated chagasic patients from endemic zones, as seen in Central Brazil in patients infected with strains of the biodeme type III, Z1 (T. cruzi I) as compared with those infected with biodeme II, Z2 (T. cruzi II) (Andrade et al 1992).…”