Biological, biochemical and molecular features of Trypanosoma cruzi strains isolated from patients infected through oral transmission during a 2005 outbreak in the state of Santa Catarina, Brazil: its correspondence with the new T. cruzi Taxonomy Consensus (2009)

We examined strains of Trypanosoma cruzi isolated from patients with acute Chagas disease that had been acquired by oral transmission in the state of Santa Catarina, Brazil (2005) and two isolates that had been obtained from a marsupial (Didelphis aurita) and a vector (Triatoma tibiamaculata). These strains were characterised through their biological behaviour and isoenzymic profiles and genotyped according to the new Taxonomy Consensus (2009) based on the discrete typing unities, that is, T. cruzi genotypes I-VI. All strains exhibited the biological behaviour of biodeme type II. In six isolates, late peaks of parasitaemia, beyond the 20th day, suggested a double infection with biodemes II + III. Isoenzymes revealed Z2 or mixed Z1 and Z2 profiles. Genotyping was performed using three polymorphic genes (cytochrome oxidase II, spliced leader intergenic region and 24Sα rRNA) and the restriction fragment length polymorphism of the kDNA minicircles. Based on these markers, all but four isolates were characterised as T. cruzi II genotypes. Four mixed populations were identified: SC90, SC93 and SC97 (T. cruzi I + T. cruzi II) and SC95 (T. cruzi I + T. cruzi VI). Comparison of the results obtained by different methods was essential for the correct identification of the mixed populations and major lineages involved indicating that characterisation by different methods can provide new insights into the relationship between phenotypic and genotypic aspects of parasite behaviour.

Clonal structure of Trypanosoma cruzi Colombian strain (biodeme Type III): biological, isoenzymic and histopathological analysis of seven isolated clones

The clonal structure of the Colombian strain of Trypanosoma cruzi, biodeme Type III and zymodeme 1, was analyzed in order to characterize its populations and to establish its homogeneity or heterogeneity. Seven isolated clones presented the basic characteristics of Biodeme Type III, with the same patterns of parasitemic curves, tissue tropism to skeletal muscle and myocardium, high pathogenicity with extensive necrotic-inflammatory lesions from the 20th to 30th day of infection. The parental strain and its clones C1, C3, C4 and C6, determined the higher levels of parasitemia, 20 to 30 days of infection, with high mortality rate up to 30 days (79 to 100%); clones C2, C5 and C7 presented lower levels of parasitemia, with low mortality rates (7.6 to 23%). Isoenzymic patterns, characteristic of zymodeme 1, (Z1) were similar for the parental strain and its seven clones. Results point to a phenotypic homogeneity of the clones isolated from the Colombian strain and suggest the predominance of a principal clone, responsible for the biological behavior of the parental strain and clones.

A estrutura clonal da cepa Colombiana do Trypanosoma cruzi, biodema Tipo III e zimodema 1, foi analisada com o objetivo de caracterizar as suas populações e estabelecer a homogeneidade ou heterogeneidade das mesmas. Foram isolados sete clones, os quais apresentaram as características básicas do biodema Tipo III, com o mesmo padrão de curvas parasitêmicas, tropismo tecidual para músculo esquelético e miocárdio, alta patogenicidade, com extensas lesões necrótico-inflamatórias, do 20º ao 30º dia de infecção. A cepa parental e os clones C1, C3, C4 e C6 apresentaram os niveis mais elevados de parasitemia entre 20 e 30 dias pós-infecção e alto indice de mortalidade até 30 dias (79 a 100%); os clones C2, C5 e C7 apresentaram niveis mais baixos de parasitemia com baixa mortalidade até 30 dias (7,6 a 23%). Os padrões isoenzimáticos foram característicos do zimodema 1 (Z1) para a cepa parental e os sete clones. Os achados do presente trabalho indicam uma homogeneidade fenotípica entre os clones isolados da cepa Colombiana e sugerem a predominância de um clone principal, responsável pelo padrão de comportamento biológico da cepa parental e dos clones.