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Infect Immun, February 1998, p. 786-793, Vol. 66, No. 2
Discipline of Cell Biology,
Received 6 August 1997/Returned for modification 30 September
1997/Accepted 7 November 1997
The 43-kDa glycoprotein of Paracoccidioides
brasiliensis is the major diagnostic antigen of
paracoccidioidomycosis, the prevalent systemic mycosis of Latin
America. Apart from eliciting high antibody titers, gp43 is also
immunodominant in delayed-type hypersensitivity reactions in infected
animals and humans. The cellular immune response in mice to gp43
administered in complete Freund's adjuvant involves CD4+
Th-1 lymphocytes, secreting gamma interferon (IFN-
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Mapping of the T-Cell Epitope in the Major
43-Kilodalton Glycoprotein of Paracoccidioides brasiliensis
Which Induces a Th-1 Response Protective against Fungal
Infection in BALB/c Mice
) and interleukin 2 (IL-2) but not IL-4 and IL-10. The T-cell epitope of this antigen was
mapped to a 15-amino-acid peptide (P10) based on lymphoproliferations with primed cells from three different haplotypes and on a
computer-assisted protein analysis. The structural requirements of the
T-cell epitope were determined by assaying a series of P10 analogous
and truncated peptides. Only 12-mer or longer sequences were active,
confirming presentation by major histocompatibility complex II. The
HTLAIR inner core of P10 is the essential domain of the epitope, with various flanking regions possible. Immunization of mice with both gp43
and P10 led to vigorous protection against intratracheal challenge by
virulent P. brasiliensis, with a >200-fold decrease in
lung CFU and halting of dissemination to the spleen and liver. The
protective effect of P10 is mainly attributed to an IFN-
-mediated cellular immune response. Unlike gp43, which induces an antibody response compatible with both Th-1 and Th-2 activation in infected BALB/c mice, P10 does not induce a humoral response. Protection by gp43
and P10 was characterized by a few well-demarcated lung granulomas with
numerous nonviable yeast forms or resolved lesions with no detectable
fungal cells.
*
Corresponding author. Mailing address: Disciplina de
Biologia Celular, Universidade Federal de São Paulo, Rua Botucatu
862/8 andar, São Paulo, SP 04023-062, Brazil. Phone:
55-11-5084-2991. Fax: 55-11-5715877. E-mail:
travassos.dmip{at}epm.br.
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