Course of infection and histopathological lesions in mice infected with seventeen Trypanosoma cruzi strains isolated from chronic patients

Abstract

Mice were infected with blood forms of 17 Trypanosoma cruzi strains recently isolated from chronic patients, which were dassified as of low, medium or high virulence on grounds of the prepatent period, parasitemia and mortality at the acute phase. A total of 212 mice were studied after 3, 6, 9 and 12 months of infection. In the chronic phase, intracellular parasites were detected in 11.0%,27.9%and 54.0,% of mice inoculated, respectively, with the low, medium and high virulent strains (r= 0.98, p < 0.005). Heart fibrosis was also related to virulence, affecting 5.7%, 11.6%and30.8% (r = 0.98, p < 0.001) of the mice inoculated with the above strains; a similar relationship was observed between intensity and frequency of the heart inflammatory reaction and the severity of infection at its early stage. Necrotizing arteritis was detected in 12.2% of the inoculated animals and this lesion was related to the infection duration rather than to strain characteristics. Inflammatory lesions and tissue parasitism were stable within the period of observation, whereas fibrosis was Progressive. The findings suggest that mice may reproduce heart lesions resembling human pathology and that organ damage apparently depends on the parasite virulence.

Host and parasite genetics shape a link between Trypanosoma cruzi infection dynamics and chronic cardiomyopathy

“…The extent of intra‐lineage genetic diversity, particularly within TcI, means that these differences should not be extrapolated to suggest that TcI is, in general, more virulent than TcVI. The potential for strain‐dependent variation in chronic cardiomyopathy presentation and severity is known to exist, even between closely related parasites (Schlemper et al , ; Andrade, ). In this study, the infection dynamics of TcI‐JR and TcI‐X10 varied in some respects and other TcI‐X10 clones are known to differ in virulence (Postan et al , ).…”

Characterization of Trypanosoma cruzi Strains Isolated from Chronic Chagasic Patients, Triatomines and Opossums Naturally Infected from the State of Rio Grande do Sul, Brazil

“…On the other hand, strains (RS11 and RS21) isolated from P. megistus were highly virulent to mice. T. cruzi of high, medium and low virulence and strains that did not induce patent parasitemia in mice have been isolated from chronic chagasic patients (Schlemper Jr et al 1983, Carneiro et al 1991 and from sylvatic reservoirs and vectors (Steindel 1993). Our results confirm the predominance of T. cruzi strains of low virulence to mice in chronic chagasic patients.…”

Biological factors that impinge on Chagas disease drug development

“…There is substantial intra-lineage genetic diversity, particularly within TcI, II, III and IV (Lewis et al 2011 ); however, this has rarely been taken into account, because in most studies, genotyping is only conducted at the lineage level. Studies using experimental animal models do show that there can be important differences in virulence between individual strains (Schlemper et al 1983 ; Postan et al 1987 ; Espinoza et al 2010 ; Rodriguez et al 2014 ; Lewis et al 2016 ), although no candidate genetic factors have been identified. The increasing availability of genomic technologies should enable progress to be made in delineating the extent to which parasite genetics contributes to disease outcome.…”