In Vitro Binding of Trypanosoma congolense to Erythrocytes*

Abstract

Trypanosoma congolense Broden, an intravascular parasite, binds to vessel walls and erythrocytes of infected hosts. In an attempt to characterize T. congolense adhesion to host cells, an in vitro assay was devised. It was shown in the in vitro experiments that T. congolense binds to bovine, sheep, and goat erythrocytes, but not always to erythrocytes of rats, mice, rabbits, horses or humans. Only the anterior part of live trypanosomes adheres to erythrocytes, and the attachment site on the trypanosomes is destroyed by trypsin and chymotrypsin-trypanosomes did not adhere to bovine erythrocytes that had been incubated with neuraminidase, sodium periodate and poly-L-lysine. The foregoing experiments suggest that the surface of T. congolense contains a protein-associated site which binds to sialic acid of some host cells. This surface site is most likely responsible for attachment to blood vessels in vivo.

The interaction ofTrypanosoma congolensewith endothelial cells

“…Frame and C. A. Ross 640 The reduction in adherence after protease treatment of trypanosomes in these studies suggests a similar occurrence in T. congolense. Thirdly, it is interesting to note that attachment of T. congolense to red blood cells appeared to be mediated by sialic acid residues on the erythrocyte surface, and could be abolished by protease treatment (Banks, 1979). This interaction, however, could be inhibited by poly-L-lysine, which saturates the negatively charged sialic acid residues on the erythrocyte surface.…”

“…However, this organelle appears to play a key role in the cell adhesion events which occur at different lifecycle stages within the insect vector and in animal hosts. In infected animals, T. congolense bloodstream forms are found adhering to erythrocytes and to endothelial cells of the microvasculature through their flagellum (Banks, 1978(Banks, , 1979(Banks, , 1980. The direct effects of this process are not entirely understood, but the tissue surrounding the adhesion sites is damaged by release of a vascular permeabilization factor, and the subsequent action of the host's immune system (Banks, 1980).…”

Distribution of cobalt, manganese and iron in the skin and hair of West African dwarf sheep and goats in Nigeria

“…We do not for certain the reason for these differences some of which are statistically significant, but we do suggest that they indicate a degree of microstructural differences between these species. Could these differences include the micro-vasculature, as manganese has been associated with the membranes of erythrocytes and mitochondria (Banks, 1979;Esievo et. al., 1986)?…”

Determination of the Disulfide Bonds within a B Domain Variant Surface Glycoprotein from Trypanosoma congolense

“…Peak 1 was found to contain equimolar amounts of the fragments Ile 14 -Arg 17 and Asp 234 -Arg 239 . In one of the radioactive fractions obtained from an alternate purification of the tryptic digest in ammonium acetate (data not shown), these fragments were also found by sequence analysis to coelute, which proves that they are covalently bound through a disulfide bridge between cysteine residues 16 and 236.…”

“…The variable surface structures might reflect different surface properties of bloodstream trypanosomes. It is known that, contrary to T. brucei, bloodstream T. congolense can be agglutinated by lectins (15,16) and are able to bind to erythrocytes (17) and endothelial cells (18 -20). The latter effect is restricted to the flagellar region and is certainly not produced by VSGs (19).…”