RESUMO
In this study, we investigated in dogs the immunogenicity and protective immunity against Leishmania (Leishmania) chagasi infection induced by vaccination with a formulation containing the recombinant A2 protein, an amastigote specific antigen, and saponin. Vaccinated animals produced significantly increased levels of total IgG and IgG2, but not IgG1 anti-A2 antibodies, and remained negative in conventional leishmaniasis serodiagnostic methods. Significantly increased IFN-gamma and low IL-10 levels were detected in vaccinated animals before and after challenge, as compared to control animals. Importantly, while the symptoms onset appeared as early as three months after infection in most control dogs, 14 months after challenge, 5 out of 7 vaccinated dogs remained asymptomatic. Therefore, immunization with rA2 antigen was immunogenic and induced partial protection in dogs, and allowed the serological differentiation between vaccinated and infected animals, an important requirement for a canine visceral leishmaniasis (CVL) vaccine.
Assuntos
Antígenos de Protozoários/genética , Antígenos de Protozoários/imunologia , Doenças do Cão/imunologia , Doenças do Cão/prevenção & controle , Leishmania infantum/imunologia , Leishmaniose Visceral/imunologia , Leishmaniose Visceral/veterinária , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , Vacinas Protozoárias/imunologia , Vacinas Protozoárias/uso terapêutico , Animais , Células da Medula Óssea/imunologia , Separação Celular , Citocinas/biossíntese , DNA de Protozoário/análise , DNA de Protozoário/isolamento & purificação , Cães , Ensaio de Imunoadsorção Enzimática , Imunização , Imunoglobulina G/análise , Imunoglobulina G/biossíntese , Interferon gama/análise , Interferon gama/biossíntese , Interleucina-10/análise , Interleucina-10/biossíntese , Leishmaniose Visceral/prevenção & controle , Contagem de Leucócitos , Monócitos/imunologia , Monócitos/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Vacinas Sintéticas/imunologia , Vacinas Sintéticas/uso terapêuticoRESUMO
Paracoccidioides brasiliensis is the fungus agent of paracoccidioidomycosis, a chronic systemic disease prevalent in Latin America. The aim of the present work was to evaluate the protection elicited by the immunization of BALB/c mice with radioattenuated yeast cells of P. brasiliensis. The immunization promoted a long lasting protection against highly infective yeast forms of P. brasiliensis. A 99.5% decrease in CFUs recovery was verified 90 days post challenge. At the same time the levels of IgG2a and IFN-gamma were high while a very low production of IL-10 and IL-5 was verified, suggesting that a Th1 pattern was dominant. This work shows the potential of radioattenuated yeast cells for the development of vaccines against fungi infections.