Towards the physical map of the Trypanosoma cruzi nuclear genome: construction of YAC and BAC libraries of the reference clone T. cruzi CL-Brener

Strategies to construct the physical map of the Trypanosoma cruzi nuclear genome have to capitalize on three main advantages of the parasite genome, namely (a) its small size, (b) the fact that all chromosomes can be defined, and many of them can be isolated by pulse field gel electrophoresis, and (c) the fact that simple Southern blots of electrophoretic karyotypes can be used to map sequence tagged sites and expressed sequence tags to chromosomal bands. A major drawback to cope with is the complexity of T. cruzi genetics, that hinders the construction of a comprehensive genetic map. As a first step towards physical mapping, we report the construction and partial characterization of a T. cruzi CL-Brener genomic library in yeast artificial chromosomes (YACs) that consists of 2,770 individual YACs with a mean insert size of 365 kb encompassing around 10 genomic equivalents. Two libraries in bacterial artificial chromosomes (BACs) have been constructed, BACI and BACII. Both libraries represent about three genome equivalents. A third BAC library (BAC III) is being constructed. YACs and BACs are invaluable tools for physical mapping. More generally, they have to be considered as a common resource for research in Chagas disease.

[The Dot immunoenzymatic assay on nitrocellulose (Dot-ELISA) in the diagnosis of Chagas disease. II. Seroepidemiologic study in 4 rural communities of Venezuela]

A survey of human Trypanosoma cruzi infection in four rural communities of two Venezuelan states with different epidemiological Chagas' disease situations was carried out using the Dot-ELISA and conventional serology. In the two hamlets of Zulia state, no seropositives were found in the under-15 age group whereas seropositivity in the over-15 group was 15.6%. In Cojedes state, the two hamlets studied exhibited a seropositivity of 8.9% in the under-15 group and 51.6% in the over-15 group. Upon comparison with conventional methods, Dot-ELISA evidenced high co-positivity, co-negativity and efficiency indexes. In the samples taken from Zulia, the predictive value of the test was 66% and 60% for cytoplasmatic and integral antigens, respectively; with the Cojedes samples, 100% and 95%. The results suggest that Dot-ELISA could be a practical alternative for seroepidemiological Chagas' disease studies in underdeveloped regions.