Are our laboratory "strains" representative samples of Trypanosoma cruzi populations that circulate in nature?

Geographical, landscape and host associations of Trypanosoma cruzi DTUs and lineages

“…Previous studies provide evidence that hosts do not circulate all parasite populations all the time, in addition to segregation of infra-populations in different tissues and blood [16, 25, 27]. These studies clearly demonstrate that in vitro or in vivo passage of parasite populations further selects for haplotypes, which bias interpretation of genetic diversity [61, 62].…”

“…An additional and more pressing problem for analyzing T.cruzi ’s genetic diversity, variation, or structuring from a landscape perspective is the fact that, in general, most data are generated from culture or laboratory animal selected populations (parasite isolates). These difficulties to analyze parasite populations in all hosts have created voids in knowledge of intra-host and metapopulation dynamics, in addition to limitations from study designs and sampling methods, including ex-host selection (in vitro or in vivo) documented previously [25–27]. …”

Trypanosoma cruzi: Maintenance in Culture Modify Gene and Antigenic Expression of Metacyclic Trypomastigotes

“…However, these in vitro induced metacyclic trypomastigotes progressively loose their virulence after 78 days in culture and became almost avirulent for mice at the end of 256 days in culture. The loss of virulence of EP-strain maintained by long terms in culture could be explained by selection of a low-virulent subpopulation (Deane et al 1984, Garcia et al 1986). These results, taken together with previous evidences showing that metacyclic trypomastigotes of the Dm30L-clone maintained in mice condition had increased virulence (Contreras et al 1994), and knowing that a full avirulent parasite for vertebrate host no may be maintained in nature, suggest that our maintenance conditions in laboratory is affecting intrinsically the biological properties of metacyclic trypomastigotes.…”

Characterization of a Trypanosoma rangeli Strain of Colombian Origin

“…Indeed, authors working with bloodstream trypomasytigotes and non-professional phagocytic cells like VERO or BEMS cells (Bertelli & Brener 1980), fibroblasts (Kongtong & Inoki 1975), primary heart or skeletal muscle cells ) pointed out to the need of at least 9-24 hr of parasite contact to obtain indexes varying between 1 and 9% of infected cells, depending on the parasite strain used. Comparative studies between T. rangeli and T. cruzi strains are controversial due to the heterogeneity of clonal populations within a T. cruzi strain (Deane et al 1984, Dvorak 1984, Tibayrenc & Ayala 1988, De Diego et al 1991, Penin et al 1996.…”