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Infection and Immunity, November 2003, p. 6184-6191, Vol. 71, No. 11
0019-9567/03/$08.00+0     DOI: 10.1128/IAI.71.11.6184-6191.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Infection by Trypanosoma cruzi Metacyclic Forms Deficient in gp82 but Expressing a Related Surface Molecule, gp30

Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, S.P.,¹ Laboratório de Doença de Chagas, Hospital das Clínicas/Faculdade de Medicina, Universidade Federal de Goiás, GoiÂnia, Goiás, Brazil²

Received 10 March 2003/ Returned for modification 5 May 2003/ Accepted 6 August 2003

Trypanosoma cruzi metacyclic trypomastigotes invade and replicate in the gastric mucosal epithelium after oral infection. In this study we analyzed the process of infection by T. cruzi isolates deficient in the expression of gp82, the metacyclic stage-specific surface glycoprotein implicated in target cell entry in vitro and in promoting mucosal infection in mice after oral challenge. Mice infected by the oral route with metacyclic forms of gp82-deficient isolate 569 or 588 developed patent parasitemia but at greatly reduced levels compared to those infected with the gp82-expressing isolate CL. Metacyclic forms of both isolates expressed gp30, a surface glycoprotein detectable by monoclonal antibody (MAb) 3F6 directed to gp82. Otherwise, the gp82-deficient isolates displayed a surface profile similar to that of the CL isolate and also entered epithelial HeLa cells in a manner inhibitable by MAb 3F6 and dependent on the parasite signal transduction that involved the activation of protein tyrosine kinase and Ca²⁺ mobilization from thapsigargin-sensitive stores. Like gp82, gp30 triggered the host cell Ca²⁺ response required for parasite internalization. Purified gp30 and the recombinant gp82 inhibited HeLa cell invasion of metacyclic forms of isolates 569 and 588 by 90 and 70%, respectively. A cell invasion assay performed in the presence of gastric mucin, mimicking the in vivo infection, showed an inhibition of 70 to 75% in the internalization of gp82-deficient isolates but not of the CL isolate. The recombinant gp82 exhibited an adhesive capacity toward gastric mucin much higher than that of gp30. Taken together, our findings indicate that target cell entry of metacyclic trypomastigotes can be mediated either by gp82 or gp30 but that efficient mucosal infection depends on the expression of gp82.

Editor: J. M. Mansfield

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