Immunization with excreted/secreted proteins in AS/n mice activating cellular and humoral response against Toxoplasma gondii infection

Author(s)

Costa-Silva, Thais Alves ^[1] ; Borges, Monamaris Marques ^[2] ; Galhardo, Cynthia Soares ^[2] ; Pereira-Chioccola, Vera Lucia ^[1]

Affiliation

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

^[2] Inst Butantan, Bacteriol Lab, Sao Paulo - Brazil

• Document type: Journal article
• Source: Acta Tropica; v. 124, n. 3, p. 203-209, DEC 2012.
• Web of Science Citations: 10

Abstract

This study investigated how Toxoplasma gondii excretory-secretory antigens (ESA) stimulate the humoral and cellular response in infected hosts. We evaluated IFN-gamma, IL-4 TNF-alpha, and IL-10 levels as well as humoral response of ESA-immunized AS/n mice. T. gondii lysate antigen (TLA), a crude antigen, was used in all experiments to evaluate the immune response. Chronic infected and naive mice were used as control groups, since the immune response is well known. The challenge experiments showed the parasitemia levels, determined by real time PCR and survival index. The naive group had early mortality and higher parasitemia than the ESA-immunized mouse group. In addition the chronic infected group had no parasitemia and mortality. Both ESA-immunized and chronic infected mice produced a similar level of IFN-gamma and TNF-alpha. ESA, also, activated cells from immunized mice to produce IL-4 and IL-10 in lower levels compared to those cells collected from chronic mice but sufficient to modulate IFN-gamma and TNF-alpha synthesis, preventing an excessive immune response that could cause extensive inflammation and host tissue damage. After 6 weeks, ESA-immunized mice had low IgM and IgG2a levels and high IgG1 levels. Purified anti-ESA IgG were able to opsonize tachyzoites (RH strain), and mice that received these parasites had lower parasitemia, and mortality was delayed 48 h, compared with the same results from those receiving parasites opsonized with IgG purified from naive mice. The protective immune response in the chronic infection was efficient in protecting the host against infection caused by other T. gondii strain and ESA participate in stimulating the host humoral and cellular responses. The immunization assays showed that ESA can elicit high IgG1, IFN-gamma and TNF-alpha production and, a lower amount of IgM, IgG2, IL-10 and IL-4, suggesting a mixed Th1/Th2 profile. (c) 2012 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 11/13939-8 - Study of a group of fungal and parasitic infections aiming the improvement of techniques of characterization and immune-molecular diagnosis
• Grantee: Vera Lúcia Pereira Chioccola
• Support Opportunities: Regular Research Grants