ÿþ<HTML><HEAD><TITLE>XI International Meeting on Paracoccidioidomycosis</TITLE><link rel=STYLESHEET type=text/css href=css.css></HEAD><BODY aLink=#ff0000 bgColor=#FFFFFF leftMargin=0 link=#000000 text=#000000 topMargin=0 vLink=#000000 marginheight=0 marginwidth=0><table align=center width=700 cellpadding=0 cellspacing=0><tr><td align=left bgcolor=#cccccc valign=top width=550><font face=arial size=2><strong><font face=Verdana, Arial, Helvetica, sans-serif size=3><font size=1>XI International Meeting on Paracoccidioidomycosis</font></font></strong><font face=Verdana size=1><b><br></b></font><font face=Verdana, Arial,Helvetica, sans-serif size=1><strong> </strong></font></font></td><td align=right bgcolor=#cccccc valign=top width=150><font face=arial size=2><strong><font face=Verdana, Arial, Helvetica, sans-serif size=1><font size=1>Resume:35-2</font></em></font></strong></font></td></tr><tr><td colspan=2><br><br><table align=center width=700><tr><td><b>Oral / Poster</b><br><table width="100%"><tr><td width="60">35-2</td><td><b>Immunogenic evaluation of Paracoccidioides brasiliensis radioattenuated yeast in murine model</b></td></tr><tr><td valign=top>Authors:</td><td><u>Estefânia Mara Nascimento Martins </u> (UFMG - Universidade Federal de Minas Gerais) ; Viviane Cristina Fernandes (UFMG - Universidade Federal de Minas Gerais) ; Alfredo Miranda Goes (UFMG - Universidade Federal de Minas Gerais) ; Maria Aparecida de Resende (UFMG - Universidade Federal de Minas Gerais) ; Antero Silva Ribeiro de Andrade (CDTN/CNEN - Centro de Desenvolvimento da energia nuclear) </td></tr></table><p align=justify><b><font size=2>Abstract</font></b><p align=justify class=tres><font size=2><i>Paracoccidioides brasiliensis</i> is the agent of paracoccidioidomycosis (PCM), a chronic systemic disease prevalent in Latin American, which is characterized by the formation of granulomatous lesions. To date, there is no effective vaccine to PCM or to any systemic mycosis. In an attempt to induce an efficient response to such agent in an animal model, gamma irradiation attenuated <i>P. brasiliensis</i> yeast cells (LevRad) were developed at the Radiobiology Laboratory from CDTN/CNEN. A gamma irradiation dose was defined in which the pathogen loses its ability to multiply, while retaining its viability, metabolic activity and antigenic profile. The prophylactic potential of LevRad was assessed after its intravenous administration in male Balb/C mice, challenged 30 days after immunization with intratracheal administration of a highly virulent non-irradiated <i>P.brasiliensis</i> isolate. At 30 and 90 days post challenge (dpc), lungs, spleen and liver were collected to analyse CFU (colony forming units) recovery, histology, cell proliferation, cytokine (IFN &gamma, IL-4, IL-10, TNF-&alpha and TGF-&beta) and iNOS production. The sera were used to evaluate the immunization efficacy, and to assess IgG isotypes (IgG1, IgG2a, IgG2b, IgG3) and total IgG levels. The present data show that there was no significant decrease in the CFU counts of the lungs of immunized animals 30 dpc. Nevertheless, no CFU or histopathological alterations were visualized at the organs of immunized animals at 90 dpc. During the same period, IgG2a, IgG2b, INF-&alpha and iNOS levels raised while IL-10, TNF-&alpha, TGF-&beta and IL-4 maintained low levels, suggesting the prevalence of Th1 response profile. Our results confirmed the protective effect conferred by the LevRad immunization in male Balb/C mice, as shown at 90 days post challenge.</font></p><br><b>Keyword: </b>&nbsp;gamma irradiation, Paracoccidioides brasiliensis, Paracoccidiodomycosis, vaccine</td></tr></table></tr></td></table></body></html>