Sm29, but not Sm22.6 retains its ability to induce a protective immune response in mice previously exposed to a Schistosoma mansoni infection.
BACKGROUND
A vaccine against schistosomiasis would have a great impact in disease elimination. Sm29 and Sm22.6 are two parasite tegument proteins which represent promising antigens to compose a vaccine. These antigens have been associated with resistance to infection and reinfection in individuals living in endemic area for the disease and induced partial protection when evaluated in immunization trials using naïve mice.
In this study we evaluated rSm29 and rSm22.6 ability to induce protection in Balb/c mice that had been previously infected with S. mansoni and further treated with Praziquantel. Our results demonstrate that three doses of the vaccine containing rSm29 were necessary to elicit significant protection (26%-48%). Immunization of mice with rSm29 induced a significant production of IL-2, IFN-γ, IL-17, IL-4; significant production of specific antibodies; increased percentage of CD4+ central memory cells in comparison with infected and treated saline group and increased percentage of CD4+ effector memory cells in comparison with naïve Balb/c mice immunized with rSm29. On the other hand, although immunization with Sm22.6 induced a robust immune response, it failed to induce protection.


CONCLUSIONS
Our results demonstrate that rSm29 retains its ability to induce protection in previously infected animals, reinforcing its potential as a vaccine candidate.
Laboratório de Esquistossomose, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Barro Preto, Belo Horizonte, Minas Gerais, Brasil.
Clarice Carvalho
CC
Alves
Laboratório de Esquistossomose, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Barro Preto, Belo Horizonte, Minas Gerais, Brasil.
Neusa
N
Araujo
Laboratório de Esquistossomose, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Barro Preto, Belo Horizonte, Minas Gerais, Brasil.
Viviane Cristina Fernandes
VC
dos Santos
Laboratório de Esquistossomose, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Barro Preto, Belo Horizonte, Minas Gerais, Brasil.
Flávia Bubula
FB
Couto
Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte, Minas Gerais, Brasil.
Natan R G
NR
Assis
Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte, Minas Gerais, Brasil.
Suellen B
SB
Morais
Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte, Minas Gerais, Brasil; Instituto Nacional de Ciências e Tecnologia em Doenças Tropicais (INCT-DT), CNPq, MCT, Salvador, Bahia, Brasil.
Sérgio Costa
SC
Oliveira
Laboratório de Esquistossomose, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Barro Preto, Belo Horizonte, Minas Gerais, Brasil; Instituto Nacional de Ciências e Tecnologia em Doenças Tropicais (INCT-DT), CNPq, MCT, Salvador, Bahia, Brasil.
Cristina Toscano
CT
Fonseca
D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D000947:Antigens, Helminth / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D016207:Cytokines / Q000097:blood; D005260:Female; D015801:Helminth Proteins / Q000276:immunology*; D006801:Humans; D007114:Immunization; D007074:Immunoglobulin G / Q000097:blood; D007156:Immunologic Memory; D008562:Membrane Glycoproteins / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D012550:Schistosoma mansoni / Q000276:immunology; D012555:Schistosomiasis mansoni / Q000276:immunology*; D014612:Vaccines / Q000276:immunology
D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D016207:Cytokines; D015801:Helminth Proteins; D007074:Immunoglobulin G; D008562:Membrane Glycoproteins; C000589456:Sm29 protein, Schistosoma mansoni; D014612:Vaccines