Home Economics American Trypanosomiasis Chagas Disease, Second Edition: One Hundred Years of Research
Conclusions and future research
In conclusion, the concept that genetic exchange is of little importance to T. cruzi is no longer tenable. Experimental work has demonstrated that T. cruzi has an extant capacity for genetic exchange, albeit by a somewhat unusual mechanism of fusion of diploids and genome erosion. Inter-lineage genetic exchange, though infrequent, has clearly shaped the evolution of the species, giving rise to at least two of the
principal DTUs, TcV and TcVI. Furthermore, this has had a profound epidemiological impact: TcV and TcVI are widespread and probably recently dispersed agents of Chagas disease. Mechanisms of genetic exchange in natural populations may be more varied and distinct from fusion of diploids and genome erosion discovered in the laboratory. Mitochondrial introgression is emerging as a common feature of both inter- and Inter-lineage recombination events. Analyses of spatiotemporally appropriate, multiclonal samples have identified cases of frequently recombining TcI populations. Further experimental crosses, combined with genome-scale sequence analysis of parents and hybrids, as well as higher resolution analysis of natural hybrids and their putative parents, should soon yield insights into the mechanisms of genetic exchange in T. cruzi.
In terms of control of Chagas disease, it is important to re-examine the association of T. cruzi genotypes with drug susceptibility, virulence, and pathogenesis, all of which are traits that may be rapidly spread by genetic exchange within and between lineages. Given the high level of genetic diversity within T. cruzi and the complexity of its population structure(s), new drugs should be tested against representatives of all the lineages, including hybrid strains.
|< Prev||CONTENTS||Next >|