The search toward the establishment of novel serological tests for the diagnosis of leishmaniasis and proper differential diagnosis may represent one alternative to the invasive parasitological methods currently used to identify infected individuals. In the present work, we investigated the potential use of recombinant peroxidoxin (rPeroxidoxin) of Leishmania (Viannia) braziliensis as a potential antigen for the immunodiagnosis of human tegumentary (TL) and visceral leishmaniasis (VL) and canine visceral leishmaniasis (CVL). Linear B-cell epitope mapping was performed to identify polymorphic epitopes when comparing orthologous sequences present in Trypanosoma cruzi, the agent for Chagas disease (CD), and the Homo sapiens and Canis familiaris hosts. The serological assay (ELISA) demonstrated that TL, VL and CVL individuals showed high levels of antibodies against rPeroxidoxin, allowing identification of infected ones with considerable sensitivity and great ability to discriminate (specificity) between non-infected and CD individuals (98.46% and 100%; 98.18% and 95.71%; 95.79% and 100%, respectively). An rPeroxidoxin ELISA also showed a greater ability to discriminate between vaccinated and infected animals, which is an important requirement for the public campaign control of CVL. A depletion ELISA assay using soluble peptides of this B-cell epitope confirmed the recognition of these sites only by Leishmania-infected individuals. Moreover, this work identifies two antigenic polymorphic linear B-cell epitopes of L. braziliensis. Specific recognition of TL and VL patients was confirmed by significantly decreased IgG reactivity against rPeroxidoxin after depletion of peptide-1- and peptide-2-specific antibodies (peptide 1: reduced by 32%, 42% and 5% for CL, ML and VL, respectively; peptide-2: reduced by 24%, 22% and 13% for CL, ML and VL, respectively) and only peptide-2 for CVL (reduced 9%). Overall, rPeroxidoxin may be a potential antigen for the immunodiagnosis of TL, VL or CVL, as it has a higher agreement with parasitological assays and is better than other reference tests that use soluble Leishmania antigens for diagnosing CVL in Brazil (EIE-LVC, Bio-manguinhos, FIOCRUZ).

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Obrigada aos meus tios Célio, Wanda, Edgar e Luzia, a segunda família que me apoia em todos os momentos. Obrigada à vovó, que nunca se esquece de mim em suas orações. Agradeço aos amigos do Laboratório de Análises Bioquímicas da Universidade Federal de Viçosa pela companhia, pelos conselhos, pelas risadas, pelos aprendizados e por todos os bons momentos. Em especial a Gabriela, companheira de trabalho. Obrigada aos colegas do Laboratório de Biologia Estrutural da Universidade Federal de Minas Gerais por toda ajuda e companheirismo, em especial a Mariana. Obrigada também aos amigos do Laboratório de Sinalização Celular, sem os quais a caminhada não teria sido a mesma. Saibam que vocês fizeram toda a diferença. Obrigada, em especial, ao Jammil que, além de me ajudar nos experimentos, tornou-se um amigo. Obrigada à CAPES pelo apoio financeiro e ao Programa de Pós-Graduação em Bioquímica e Imunologia da Universidade Federal de Minas Gerais por me permitirem realizar esse projeto. Em fim, obrigada a todos aqueles que não citei mas que contribuíram, de alguma forma, para que eu pudesse alcançar meu objetivo. "Espera no Senhor e tem coragem.