The effect of 9
monosaccharides which constitute cell surface
carbohydrates on the
infection of bovine embryonic skin and muscle (BESM) cells by Trypanosoma cruzi trypomastigotes and Toxoplasma gondii tachyzoites was assayed. Most of the
monosaccharides tested stimulated the
infection of BESM cells by T. gondii; none of the
monosaccharides were inhibitory. In contrast (at a concentration of 50 mM or greater) the
monosaccharides inhibited non-specifically the
infection of BESM cells by T. cruzi trypomastigotes whereas the other 8
monosaccharides were ineffective. The inhibition was due to an effect on the trypomastigotes and not on the vertebrate cells. It is proposed that there is a
wheat-germ agglutinin-like
lectin on the T. cruzi trypomastigote surface which recognizes and attaches to an
N-acetylglucosamine-containing receptor on the vertebrate cell surface prior to
infection.
Infection of vertebrate cells by T. gondii tachyzoites appears to be mediated by other cell surface components. If
monosaccharides are involved in
infection by tachyzoites, they are ones not commonly found on animal cell surfaces. Alternatively,
infection of vertebrate cells by T. cruzi and T. gondii is effected by different mechanisms.