Evaluation of immunization with tachyzoite excreted-secreted proteins in a novel susceptible mouse model (A/Sn) for Toxoplasma gondii

Autor(es)

Costa-Silva, Thais A. ^[1] ; Meira, Cristina S. ^[1] ; Ferreira, Isabelle M. R. ^[1] ; Hiramoto, Roberto M. ^[1] ; Pereira-Chioccola, Vera L. ^[1]

Afiliação do(s) autor(es)

^[1] Inst Adolfo Lutz Registro, Dept Parasitol, Parasitol Lab, BR-01246902 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Experimental Parasitology; v. 120, n. 3, p. 227-234, NOV 2008.
• Citações Web of Science: 21

Resumo

Toxoplasma gondii is an important food-borne parasite transmitted primarily from animals to humans through meat consumption, mainly pork and lamb, as well as through oocysts shed by cats. Infection in humans can cause severe neonatal malformations, ocular complications or encephalitis. Toxoplasmosis infection during pregnancy, especially in sheep, often results in abortion, representing considerable economic loss. The aim of this study was to investigate whether Toxoplasma gondii pooled excreted-secreted antigens (ESA), recovered from infected culture supernatants with tachyzoites used as immunogen, can protect experimental mice against T. gondii infection. For immunization experiments, we evaluated A/Sn inbred mice, a novel susceptible mouse model for T gondii and a virulent strain (RH) for challenge experiments. The antigen selection was based on those produced by tachyzoites since they are responsible for disseminating the infection as well as stimulating the humoral and cellular immune responses. ESA were recovered from VERO cell-culture supernatants infected with virulent RH strain tachyzoites harvested after 48 h. Groups of 5 female mice were intraperitoneally (i.p.) immunized with 4 doses at 2 week intervals with 20 mu g of ESA adsorbed to 0.5 mg of alum. The control group received only the adjuvant in PBS on the same dates. Pooled serum collected from chronically infected mice was used as positive control. Blood samples were collected from tail veins 14 days after each immunization. Antibody was detected using ELISA, indirect immunofluorescence and immunoblotting. Anti-ESA antibodies were also evaluated by agglutination, complement-mediated lysis and antibody-mediated cellular toxicity. Fifteen days after the last immunization, both groups were challenged (i.p.) with 1 x 10(3) RH strain tachyzoites. The parasitemia was evaluated by PCR. and survival was followed daily. The results showed an increase of antibody levels after each immunization. Anti-ESA antibodies also reacted with a crude tachyzoite antigen and bonded on the parasite surface, with particularly high intensity at the apical region. Anti-ESA antibodies were also able to agglutinate and kill tachyzoites in vitro through interactions with complement and cellular pathways. Even though the tachyzoite challenge was lethal to the mice. PCR results suggested that immunized mice had lower parasitemia as well as longer survival (72 h) than mice from the control group. (C) 2008 Elsevier Inc. All rights reserved. (AU)

• Processo FAPESP: 06/52673-5 - Análise do potencial antigênico das proteínas excretadas por taquizoitos de Toxoplasma gondii
• Beneficiário: Thaís Alves da Costa Silva
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 06/52674-1 - Identificacao de possiveis antigenos de toxoplasma gondii como marcadores da toxoplasmose cerebral em pacientes com aids.
• Beneficiário: Cristina da Silva Meira Strejevitch
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 05/03052-5 - Caracterização genotípica e antigênica de Toxoplasma gondii em pacientes com toxoplasmose cerebral e AIDS
• Beneficiário: Vera Lúcia Pereira Chioccola
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 06/52672-9 - Genotipagem de isolados de toxoplasma gondii de pacientes com aids e toxoplasmose cerebral e a correlacao com a doenca.
• Beneficiário: Isabelle Martins Ribeiro Ferreira
• Modalidade de apoio: Bolsas no Brasil - Mestrado