Mice Immunization with Radioattenuated Yeast Cells of Paracoccidiodes brasiliensis: Influence of the Number of Immunizations
- 60 Downloads
Paracoccidioides brasiliensis is the agent of paracoccidioidomycosis, the most prevalent mycosis in Latin America. Up to the moment no vaccine has been reported. The aim of this study was to evaluate the influence of the number of immunizations on the protection elicited by radioattenuated yeast cells of P. brasiliensis. BALB/c mice were divided into two groups that were immunized once (Group 1) or twice (Group 2), respectively. In each group, mice were divided into sub-groups that were challenged 30, 45, or 60 days after the second immunization. Organ colony-forming units (CFUs) was determined 90 days post-challenge. A significant reduction in CFUs recovery was verified in both groups, but it was higher in Group 2. Histologic alterations were observed only in Group 1. The cytokines IL-4, IL-10, and IFN-γ were produced in mice of Group 1. In Group 2, only IFN-γ was significantly detected. IgG2a predominance relative to IgG1 was also observed in Group 2. Altogether, our results indicated that mice immunized once developed a mixed Th1/Th2 response, which was less efficient in the infection control, while a trend to a Th1 pattern was obtained with two immunizations, promoting optimal elimination of P. brasiliensis yeast cells from mice tissues.
KeywordsParacoccidioides brasiliensis Vaccine Gamma irradiation Immunization
This research was supported by Fundação de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG) (CBB580/06), International Atomic Energy Agency (IAEA) (13239/R0), and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).
- 12.Soares AMVC, Peraçoli MTS, Santos RR. Correlation among immune response, morphogenesis of granulomatous reaction and spleen lymphoid structure in murine experimental paracoccidioidomycosis. Med Mycol. 2002;38:317–77.Google Scholar
- 15.Taborda CP, Nakaie CR, Cilli EM, Rodrigues EG, Silva LS, Franco M, et al. Synthesis and immunological activity of a branched peptide carrying the T-cell epitope of gp43, the major exocellular antigen of Paracoccidioides brasiliensis. Scand J Immunol. 2004;59:58–65. doi: 10.1111/j.0300-9475.2004.01359.x.PubMedCrossRefGoogle Scholar
- 17.Marques AF, da Silva MB, Juliano MAP, Travassos LR, Taborda CP. Peptide immunization as an adjuvant to chemotherapy in mice challenged intratracheally with virulent yeast cells of Paracoccidiodies brasiliensis. Antimicrob Agents Chemother.. 2006;50:2814–29. doi: 10.1128/AAC.00220-06.PubMedCrossRefGoogle Scholar
- 24.Wüthrich M, Filutowicz HI, Warner T, Deepe GS, Klein BS. Vaccine immunity to pathogenic fungi overcomes the requirement for CD4+ help in exogenous antigen presentation to CD8+ T cells: implications for vaccine development in immune-deficient hosts. J Exp Med. 2003;197:1405–16. doi: 10.1084/jem.20030109.PubMedCrossRefGoogle Scholar
- 25.Okeke C, Cole GT. Morphological defects and loss of virulence of Coccidioides posadasii caused by, disruption of CHS5, encoding a chitin synthase with myosin motor like domain. In: 103rd General Meeting of the American Society for Microbiology. Washington, D.C., May 18–22, 2003; F23 p. 227.Google Scholar
- 29.Pickering L, editor. Red book: 2006 report of the committee on infectious disease. Elk Grove Village: American Academy of Pediatrics; 2006.Google Scholar