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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Radiation effects on Toxoplasma antigens: different immune responses of irradiated intact tachyzoites or soluble antigens in experimental mice models

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da Costa, Andrea [1] ; do Nascimento, Nanci [2] ; Galisteo, Jr., Andres Jimenez [3, 1] ; Dias dos Passos, Aline Bastos [1] ; de Andrade, Jr., Heitor Franco [1]
Total Authors: 5
[1] Univ Sao Paulo, Inst Med Trop Sao Paulo, Lab Protozool, Sao Paulo - Brazil
[2] Inst Pesquisas Energet & Nucl, Ctr Biotecnol, Sao Paulo - Brazil
[3] Univ Sao Paulo, Fac Med, Hosp Clin, Sao Paulo - Brazil
Total Affiliations: 3
Document type: Journal article
Source: International Journal of Radiation Biology; v. 96, n. 5 FEB 2020.
Web of Science Citations: 0

Purpose: Purpose: Protein irradiation causes aggregation, chain breakage, and oxidation, enhancing its uptake by antigen-presenting cells. To evaluate if irradiated proteins participate on the protection, we studied the immune response induced in mice immunized with irradiated soluble extracts of T. gondii tachyzoites (STag) or irradiated intact T. gondii RH tachyzoites (RH0.25 kGy). Material and Methods: Soluble extracts of Toxoplasma gondii tachyzoites (STag) were irradiated at different dose by Cobalt-60 source. By polyacrylamide gel electrophoresis (SDS-Page) we evaluated the effects on primary structures of protein STags induced by irradiation. By Enzyme-linked Immunosorbent Assay (ELISA) we evaluated the difference between humoral immune response induced by irradiated STag or RH tachyzoites in immunized mice from the detection of specific immunoglobulin G (IgG) antibodies in the serum of immunized mice. From challenge with viable RH strain of T. gondii we evaluated the protection induced in the immunized animals. By cytometry we performed the phenotyping of T and B lymphocytes in the peripheral blood of the immunized animals. Results: Irradiation dose of 1.5 kGy induced minimal changes in most proteins, without affecting their antigenicity or immunogenicity. Immunization showed saturation at the dose of 10 mu g/mice, with worst response at higher doses. STag irradiated at 1.5 kGy (STag(1.5 kGy)) induced higher survival and protection similar to T. gondii RH strain irradiated at 0.25 kGy (RH0.25 kGy), with higher serum levels of high affinity IgG compared to STag native. Blood immune memory cells of mice immunized with STag(1.5 kGy) had higher proportions of CD19(+) (cluster of differentiation 19) and CD4(+) (cluster of differentiation 14) cells, whereas mice RH0.25 kGy had high proportion of memory CD8(+) (cluster of differentiation 8) cells. Conclusions: Our data suggest that major histocompatibility complex type I (MHCI) pathway, appears seem to be used by RH0.25 kGy to generate cytotoxic cells while STag1.5 kGy uses a major histocompatibility complex type II (MHCII) pathway for B-cell memory, but both induce sufficient immune response for protection in mice without any adjuvant. Irradiation of soluble protein extracts enhances their immune response, allowing similar protection against T. gondii in mice as compared to irradiated intact parasites. (AU)

FAPESP's process: 14/17029-4 - Mechanism of immune recognition and antigen enhanced by gamma radiation processing in toxoplasmosis
Grantee:Andrea da Costa
Support Opportunities: Scholarships in Brazil - Doctorate