No abstract

A2 was identified as an amastigote virulence factor of Leishmania (Leishmania) donovani and as a candidate antigen for vaccine development against visceral leishmaniasis. Here, predicted hydrophilic, class I and II MHC-binding synthetic peptides were used to define epitopes recognized by A2-specific antibodies, CD8+ T and CD4+ T cells, respectively. Immunization of BALB/c mice with adenovirus expressing A2 (AdA2) resulted in low antibody response, contrasting with high levels of IFN-gamma producing CD4+ T and CD8+ T cells specific for A2. Further, A2-specific CD8+ T cells from immunized mice were capable of lysing sensitized target cells in vivo. Finally, we demonstrated an association of A2-specific T cell responses and reduced parasitism in both liver and spleen from mice immunized with AdA2 and challenged with L. (L.) chagasi.

The ethyl acetate and aqueous extracts from Campomanesia adamantium showed antinociceptive and anti-inflammatory effects supporting the use of the plant in folk medicine. The results suggest that anti-oedematogenic effect promoted by aqueous extract involves several anti-inflammatory mechanisms of action. The antinociceptive effect shown by aqueous extract can be due to the modulation of release of inflammatory mediators involved in nociception. The anti-inflammatory effects of AE and of its isolated flavonols may be attributed to inhibition of pro-inflammatory cytokines production, TNF-α and NO and to the increased of IL-10 production.

Acute visceral leishmaniasis is a progressive disease caused by Leishmania chagasi in South America. The acquisition of immunity following infection suggests that vaccination is a feasible approach to protect against this disease. Since Leishmania homologue of receptors for activated C kinase (LACK) antigen is of particular interest as a vaccine candidate because of the prominent role it plays in the pathogenesis of experimental Leishmania major infection, we evaluated the potential of a p36(LACK) DNA vaccine in protecting BALB/c mice challenged with L. chagasi. In this study, mice received intramuscular (i.m.) or subcutaneous (s.c.) doses of LACK DNA vaccine. We evaluated the production of vaccine-induced cytokines and whether this immunization was able to reduce parasite load in liver and spleen. We detected a significant production of interferon gamma by splenocytes from i.m. vaccinated mice in response to L. chagasi antigen and to rLACK protein. However, we did not observe a reduction in parasite load neither in liver nor in the spleen of vaccinated animals. The lack of protection observed may be explained by a significant production of IL-10 induced by the vaccine.

Protein-energy malnutrition and visceral leishmaniasis are important problems of public health affecting millions of people worldwide. Vaccine efficacy depends on the ability of individuals to mount an appropriate immune response and may be inadequate in malnourished persons. In this study, we used a mouse model to verify the effect of combined protein, iron and zinc deficiency in the response to Leishmania chagasi antigen vaccine. BALB/c mice were fed with a low-protein (3% casein), iron- and zinc-deficient diet or control diet (14% casein and sufficient in zinc and iron). After malnutrition establishment, mice were vaccinated subcutaneously with L. chagasi Ag plus saponin. After vaccination, mice were nutritionally repleted and then all mice were challenged with L. chagasi promastigotes. Four weeks later, liver and spleen parasite load was evaluated. Our data show that vaccine caused a significant reduction in parasite load in spleen and liver from mice fed with control diet. However, splenic parasitism was increased in mice fed with deficient diet and this diet caused a reduction in splenocyte IFN-gamma production in response to the vaccine in repleted mice. These data suggest that malnutrition may alter immune response to L. chagasi vaccine in BALB/c model of infection, even after nutritional repletion.