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Infect. Immun., 07 1997, 2548-2554, Vol 65, No. 7
G Franchin, VL Pereira-Chioccola, S Schenkman and MM Rodrigues
Trypanosoma cruzi, the parasite that causes Chagas' disease, proliferates
in the cytosol of mammalian cells. When the trypomastigote forms exit the
infected cell, they become extensively sialylated because the parasite
contains an enzyme called trans-sialidase. This enzyme efficiently
catalyzes the transfer of bound sialic acid residues from host
glycoconjugates to acceptors containing terminal beta- galactosyl residues
on the parasite surface. The sialic acid acceptors are developmentally
regulated mucin-like glycoproteins that are extremely abundant on the
trypomastigote surface. In the present study, we determined whether passive
transfer of monoclonal antibodies specific for sialic acid acceptors could
reduce the acute infection induced by T. cruzi in a highly susceptible
mouse strain. We found that passive transfer to naive mice of an
immunoglobulin G1 monoclonal antibody directed to a sialylated epitope of
these mucin-like glycoproteins significantly decreased parasitemia and the
number of tissue parasites as measured by a DNA probe specific for T.
cruzi. Upon challenge with trypomastigotes, mice which received this
antibody also had a significant increase in survival. A statistically
significant reduction in parasitemia could be accomplished with relatively
small doses of immunoglobulin, and Fab fragments alone could not mediate
protective immunity. The precise mechanism of parasite elimination is
unknown; however, this monoclonal antibody does not lyse trypomastigotes in
vitro in the presence of human complement or mouse spleen cells.
Copyright © 1997, American Society for Microbiology
Passive transfer of a monoclonal antibody specific for a sialic acid- dependent epitope on the surface of Trypanosoma cruzi trypomastigotes reduces infection in mice
Department of Microbiology, Immunology, and Parasitology, Federal University of Sao Paulo-Escola Paulista de Medicina, S.P. Brazil.
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