Navegando por Autor "Bastrenta, Brigitte"

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Compared vectorial transmissibility of pure and mixed clonal genotypes of Trypanosoma cruzi in Triatoma infestans.
(1998) Pinto, Artur da Silveira; Lana, Marta de; Bastrenta, Brigitte; Barnabé, Christian; Quesney, Virginie; Noel, Sébastien; Tibayrenc, Michel
A total of 15 mixtures involving 9 di erent stocks attributed to the 19/20, 32 and 39 major clonal genotypes of Trypanosoma cruzi were used to infect third-instar nymphs of Triatoma infestans via an arti®- cial feeding device. Three biological parameters were considered: (1) the percentage of infected insects (%II), (2) the number of ¯agellates per insect (NFI), and (3) the percentage of trypomastigotes per insect (%DIF). Ge- netic characterization by both multilocus enzyme elec- trophoresis (MLEE) and random ampli®cation of polymorphic DNA (RAPD) indicated that in almost all cases (87%), mixtures remained present after completion of the whole cycle in the insect vector. Two lines of comparison were performed: (1) pure clonal genotypes versus corresponding mixed clonal genotypes and (2) the actual behavior of mixed clonal genotypes versus the expected behavior of the theoretical mixture (i.e. the arithmetic mean of the results observed for each of the two clonal genotypes taken separately). Statistical analyses of the variables were made di cult because of the presence of large standard deviations. Nevertheless, in several cases, mixtures di ered signi®cantly from pure clonal genotypes, and in one case the actual mixture di ered signi®cantly from the theoretical mixture. In some cases, interaction (either potentialization or re- ciprocal inhibition) could be suspected.
Experimental Trypanosoma cruzi biclonal infection in Triatoma infestans : detection of distinct clonal genotypes using kinetoplast DNA probes.
(2000) Pinto, Artur da Silveira; Lana, Marta de; Britto, Constança; Bastrenta, Brigitte; Tibayrenc, Michel
Monitored biclonal densities of parasites were offered to third-stage larvae of Triatoma infestans via an arti®cial feeding device and 30 days later, the gut contents of the insects were processed for microscopic examination and polymerase chain reaction (PCR) detection of Trypanosoma cruzi kinetoplast DNA [kDNA]). A total of 15 mixtures involving nine different stocks attributed to the 19/20, 32 and 39 major clonal genotypes of Trypanosoma cruzi were used. The presence of each T. cruzi clonal genotype after completion of the cycle through the insects was investigated by hybridising the PCR ampli®cation products with genotype-speci®c minicircle kDNA probes. Sixty-®ve out of 90 examined insects (72.2%) were positive for parasites by microscopic examination and 85 (94.4%) were positive by PCR. The results show that almost half of the biclonal infections are not detectable after completion of the cycle, and that there are important differences in detection of such biclonal infections according to the clonal genotypes considered. Moreover, elimination of a clonal genotype by another is a frequent, but not constant, pattern in biclonal infections of T. infestans. The use of PCR and kDNA probes makes it possible to avoid the culture phase, which makes detection of mixed infections much easier in epidemiological surveys. Moreover, the fact that T. infestansdoes not transmit different T. cruzi clonal genotypes with the same ef®ciency has strong implications for the reliability of xenogiagnosis. q 2000 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.
Trypanosoma cruzi : infectivity of clonal genotype infections in acute and chronic phases in mice.
(2000) Lana, Marta de; Pinto, Artur da Silveira; Bastrenta, Brigitte; Barnabé, Christian; Noel, Sébastien; Tibayrenc, Michel