PCR-based screening and lineage identification of Trypanosoma cruzi directly from faecal samples of triatomine bugs from northwestern Argentina

MARCET PL; DUFFY T; CARDINAL MV; BURGOS JM; LAURICELLA MA; LEVIN MJ; KITRON U; GÜRTLER RE.; SCHIJMAN AG

PARASITOLOGY

CAMBRIDGE UNIV PRESS

Año: 2006 vol. 132 p. 57 - 65

0031-1820

This study applied improved DNA extraction and polymerase chain reaction strategies for screening and identification ofTrypanosoma cruzi lineages directly from faeces of triatomines collected in a well-defined rural area in northwesternArgentina. Amplification of the variable regions of the kinetoplastid minicircle genome (kDNA-PCR) was performedin faecal lysates from 33 microscope (MO)-positive and 93 MO-negative Triatoma infestans, 2 MO-positive and 38MO-negative Triatoma guasayana and 2 MO-positive and 73 MO-negative Triatoma garciabesi. kDNA-PCR detectedT. cruzi in 91% MO-positive and 7.5% MO-negative T. infestans, which were confirmed by amplification of the minicircleconserved region. In contrast, kDNA-PCR was negative in all faecal samples from the other triatomine species. A panel ofPCR-based genomic markers (intergenic region of spliced-leader DNA, 24Sa and 18S rRNA genes and A10 sequence)was implemented to identify the parasite lineages directly in DNA lysates from faeces and culture isolates from 28 infectedspecimens. Two were found to be infected with TCI, 24 with TCIIe, 1 with TCIId and 1 revealed a mixed TCI+TCIIinfection in the faecal sample whose corresponding culture only showed TCII, providing evidence of the advantages ofdirect typing of biological samples. This study provides an upgrade in the current diagnosis and lineage identification ofT. cruzi in field-collected triatomines and shows T. cruzi II strains as predominant in the region.