Genomic variation in Trypanosoma cruzi clonal cultures

Abstract

Spontaneous changes in restriction DNA profiles and pulsed-field gel electrophoresis (PFGE) patterns, along with a concomitant loss of infectivity, were observed in infective clones of Trypanosoma cruzi strain Y either following a number of passages during the exponential growth phase of after subcloning in liver infusion tryptone (LIT) medium using as the probe a genomic fragment of the parasite (pMYP16), indicating naturally occurring rearrangements of DNA sequences. No variation could be detected when the genomic DNA was probed with conserved T. cruzi tubulin and actin genes. There was no correlation between such rearrangements and the life-cycle forms of the parasites, since trypomastigote forms showed the same karyotype and hybridization patterns as did epimastigote forms. The variations observed could be reverted and infectivity, recovered after inoculation of the parasites in newborn mice.

Impact of Dual Infections on Chemotherapeutic Efficacy in BALB/c Mice Infected with Major Genotypes ofTrypanosoma cruzi

“…These microsatellite profile changes were unexpected because we used clonal T. cruzi stocks predicted to remain genetically stable (38), even considering the possibility of genetic exchange (24). However, genetic changes have already been observed in cultures of clonal protozoan parasites as a result of drug resistance selection or even spontaneously or by modification of the culture conditions used (1,2,27,30,31,45). Furthermore, we cannot exclude the possibility that these original stocks possessed different subpopulations present at levels too low for detection by conventional molecular techniques and/or that the passage of these stocks in laboratory animals or culture propitiated the preferential growth of such subpopulations.…”

Analise do determinismo genetico da resistencia de camundongos infectados experimentalmente com a cepa Y de Trypanosoma cruzi

“…É consenso, que estes resultados, embora de extrema importância, não são conclusivos para a infecção ao 7 FUX]L requerendo a realização de outros ensaios, que permitam investigar a importância da constituição genética do hospedeiro no controle da infecção (Wrightsman et al, 1994;Wrightsman et al,1995;Wrightsman & Manning, 2000;Wrightsman et al, 2002) As análises, que até então se baseavam essencialmente no produto da expressão de genes, com o desenvolvimento de técnicas moleculares, passaram a ser realizadas com a observação direta da molécula do DNA, implicando em importantes avanços na investigação genética de mecanismos complexos, como os de resistência à infecção por patógenos intracelulares (Britto et al, 1995;Alves et al, 1996). A reação de PCR, por exemplo, consorciada à utilização de microssatélites polimórficos de DNA e acasalamentos programados, permitiu o estudo de regiões cromossômicas, envolvidas na susceptibilidade a doenças, como a infecção pelo vírus de Theiler (Bureau et al, 1993;Bureau et al, 1992;Fitte et al, 1995), animais bons e maus respondedores (Puel et al, 1995;Trezena et al, 2002), entre outros.…”