ÿþ<HTML><HEAD><TITLE>25º Congresso Brasileiro de Microbiologia </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>25º Congresso Brasileiro de Microbiologia </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>ResumoID:1414-2</font></em></font></strong></font></td></tr><tr><td colspan=2><br><br><table align=center width=700><tr><td>Área: <b>Imunologia ( Divisão E )</b><p align=justify><strong>THE IMMUNOGENIC AND PROTECTIVE EFFICACY OF RECOMBINANT MIC1 AND MIC4 MICRONEN PROTEINS IN MURINE EXPERIMENTAL TOXOPLASMOSIS</strong></p><p align=justify><b><u>Camila Figueiredo Pinzan </u></b> (<i>FMRP</i>); <b>Elaine Vicente Lourenço </b> (<i>FMRP</i>); <b>Carla Duque Lopes </b> (<i>FMRP</i>); <b>Maria Cristina Roque Antunes Barreira </b> (<i>FMRP</i>)<br><br></p><b><font size=2>Resumo</font></b><p align=justify class=tres><font size=2>Introduction and Objectives: Host cell invasion by Toxoplasma gondii parasite is preceded by release of proteins from apical secretory vesicles named micronemes. Microneme discharge is the first step in host invasion and the binding of micronemal proteins to host cells provides a molecular bridge to the parasite, thereby facilitating further steps of invasion. Our group has shown that T. gondii micronemal protein 1 and 4 can be recovered in the lactose-eluted (Lac+) fraction on affinity chromatography of the antigen from tachyzoites of the virulent RH strain. We also demonstrated that the immunization of the C57BL/6 mice with Lac+, induced efficient protection against cysts of the ME49 strain (Microbes Infect.;8(5):1244-51, 2006). In the present study we determined the immunoprotective effect conferred by immunization with MIC1 and MIC4 recombinant proteins (rMIC1 and rMIC4). Methods and Results: Following immunization with rMIC1 or rMIC4 proteins, C57BL/6 mice presented high serum titers of IgG1, IgG2a and IgG2b specific antibodies, suggesting the occurrence of a mixed type of immune response. High levels of IFN-&#61543; (3298 ± 192 and 3222 ± 98, respectively) and IL-2 (105 ± 9 and 124 ± 2, 6, respectively) were detected, whereas IL-10 and IL-4 were not detected in the spleen cells culture supernatants. The Th1-type of immunity developed in the immunized mice was showed to be protective against oral challenge with 80 cysts of the ME49 strain of T. gondii, since the number of the recovered brain cysts was 70 % lower than the occurred in non immunized mice. We also observed a decrease in mortality rates in immunized mice. Conclusion: Our results show that rMIC1 and rMIC4 are involved in the induction of immune responses towards a Th1 protective immunity and suggest that these micronemal proteins can be considered as efficient antigens in the design of vaccinal preparations against T. gondii infection. Financial support: FAPESP, FAEPA. </font></p><br><b>Palavras-chave: </b>&nbsp;Lectins, Toxoplasma gondii, Vaccine</td></tr></table></tr></td></table></body></html>