immunology of infectious and parasitic diseases - XXXVII Congress ...

SMTEG IMMUNIZATION WITHOUT AJUVANTS INDUCES A MODULATORY
IMMUNE RESPONSE IN MICE.
CLARICE CARVALHO ALVES 1 ; JULIANO MICHEL ARAUJO 1 ; TATIANE
TEIXEIRA DE MELO 1 ; ISABELA CAMPOS DE SENA 1 ; NEUSA ARAUJO 1 ;
FERNANDA DO VALLE DURÃES 2 ; DEBORAH LARANJEIRA FERREIRA
PIMENTA 1 ; SERGIO COSTA OLIVEIRA 2 ; CRISTINA TOSCANO FONSECA 1,3 .
1 Centro de Pesquisas René Rachou, Fiocruz-MG, Belo Horizonte, Minas
Gerais, Brazil; 2 Departamento de Bioquímica e imunologia, Instituto de Ciências
Biológicas, Univesidade Federal de Minas Gerais, Belo Horizonte, Minas
Gerais, Brazil; 3 Instituto Nacional de Ciências e Tecnologia em Doenças
Tropicais (INCT-DT), Brazil.
Introduction: Vaccine development is essential to control schistosomiasis
since chemotherapy does not prevent reinfections. The S. mansoni
schistosomula tegument (Smteg) is an interesting parasite structure to be used
in a vaccine formulation against schistosomiasis, since it is a dynamic hostinteractive
layer. We have recently demonstrated that Smteg is able to activate
innate immune response and to induce protective immunity reducing parasite
burden, egg elimination and disease morbidity in a vaccine formulation with
Freunds adjuvant. In this work, we evaluated the immunological response
trigged by Smteg immunization in the absence of adjuvant and its ability to elicit
protection against S. mansoni challenge infection. Methods and Results:
Female C57BL/6 mice were immunized subcutaneously with three doses of
Smteg (25µg) or saline (control group) in a 15 day-interval regimen. Thirty days
after the last boost, mice were challenged through percutaneous exposure of
abdominal skin. Fifty days after challenge, adult worms were perfused from the
portal system and the protection level was calculated. Unexpectedly,
immunization failed to induce protection in mice. To evaluate humoral immune
response, blood samples were collected from retro orbital sinus of each mouse
with an interval of 15 days beginning 15 days after the first immunization for
measurement of specific anti-Smteg antibodies. Immunization with Smteg lead
to production of specific IgG antibodies indicating that immunization was able to
activate immune response. Cytokines production (IL-4, IL-10, TNF-a, IFN-g)
was assessed by splenocytes culture and intracellular staining ten days after
the last immunization. An increased percentage of CD4+IFN-g+ (p