Molecular and biological characterization of a highly pathogenic Trypanosoma cruzi strain isolated from a patient with congenital infection

Abstract

Although many Trypanosoma cruzi (T. cruzi) strains isolated from a wide range of hosts have been characterized, there is a lack of information about biological features from vertically transmitted strains. We describe the molecular and biological characteristics of the T. cruzi VD strain isolated from a congenital Chagas disease patient. The VD strain was typified as DTU TcVI; in vitro sensitivity to nifurtimox (NFX) and beznidazole (BZ) were 2.88 μM and 6.19 μM respectively, while inhibitory concentrations for intracellular amastigotes were 0.24 μM for BZ, and 0.66 μM for NFX. Biological behavior of VD strain was studied in a mouse model of acute infection, resulting in high levels of parasitemia and mortality with a rapid clearence of bloodstream trypomastigotes when treated with BZ or NFX, preventing mortality and reducing parasitic load and intensity of inflammatory infiltrate in skeletal and cardiac muscle. Treatment-induced parasitological cure, evaluated after immunossupression were 41% and 35% for BZ and NFX treatment respectively, suggesting a partial response to these drugs in elimination of parasite burden. This exhaustive characterization of this T. cruzi strain provides the basis for inclusion of this strain in a panel of reference strains for drug screening and adds a new valuable tool for the study of experimental T. cruzi infection.

Refining drug administration in a murine model of acute infection with Trypanosoma cruzi

“…This acute model of T. cruzi infection was previously standardized and the employed VD strain shows high parasitaemia levels and high mortality rates in non-treated (NT) infected BALB/c mice [13]. Then, for this work, there was no NT group added since the aim was to present an alternative oral administration method with a reference drug.…”

“…Although T. cruzi DNA was detected in some samples from cardiac and skeletal muscle from both groups, the obtained signal was below the quantitation limit. It is important to note that VD strain shows a high tropism for skeletal muscle and therefore many T. cruzi DNA may be present at the site of infection [13]. Persistence of parasite DNA detectable but not quantifiable was consistent with parasitological cure in our model, as these results can be explained by the persistence of T. cruzi DNA in local phagocytes (as documented in previous studies [15] that may represent intra and/or extracellular granular antigens, abundant in heart and skeletal muscle during the acute phase of the infection [16].…”

“…Mice (28-35 days old; 20.12 ± 2.35 g) were infected with 1000 bloodstream trypomastigotes of T. cruzi VD strain, previously characterized [13] and maintained by serial passages in outbred CF-1 male mice. The inoculum was suspended in sterile RPMI-1640 medium and administered in a final volume of 0.2 mL per animal by intraperitoneal (ip) route.…”

The protein family TcTASV-C is a novel Trypanosoma cruzi virulence factor secreted in extracellular vesicles by trypomastigotes and highly expressed in bloodstream forms

“…cruzi stocks are kept in liquid nitrogen and all strains are regularly thawed twice a year to preserve their biological characteristics. Parasites from Sylvio (TcI), 193–173 (TcI), K98 (TcI), Y (TcII), Tul (TcVI), VD (TcVI), CL Brener (TcVI) and RA (TcVI) were employed [ 50 – 54 ].…”

Congenital Chagas Disease in the Ecuadorian Amazon: Maternal Screening at Delivery and Evaluation of Risk Factors Associated with Vector Exposure

“…In 2006, more than 15,000 new congenital cases per year were estimated in Latin America 3 ; although this number may have declined since 2006, several recent publications have reported new congenital transmission. [4][5][6] Congenital T. cruzi infection is mostly asymptomatic in newborns; however, more severe manifestations may occur 7,8 and mortality can reach up to 15% for untreated severe cases. 8 Many congenital cases remain undiagnosed and will eventually give rise to disabling cardiac or digestive pathology.…”