This study investigated the toxic effects of essential oils isolated from Siparuna guianensis against Aedes aegypti, Culex quinquefasciatus (eggs, larvae, pupae, and adult) and Aedes albopictus (C6/36) cells. The oviposition-deterring activity, egg viability, and repellence activity in the presence of different essential oils concentrations were determined. The essential oils showed high toxicity to all developmental stages of A. aegypti and C. quinquefasciatus. Furthermore, the oils also showed high repellent activity towards the adult stage of mosquitoes (0.025 to 0.550 μg/cm2 skin conferred 100% repellence up to 120 min) and in contact with cultured insect cells (C6/36) induced death possibly by necrosis. The results presented in this work show the potential of S. guianensis essential oils for the development of an alternative and effective method for the natural control of mosquitoes in homes and urban areas.

No abstract

Canine visceral leishmaniasis (CVL) is a parasitic disease endemic in many countries, and dogs present as the major natural reservoir of the parasite, Leishmania chagasi (syn. L. infantum). Biomarkers in the canine immune system is an important technique in the course of developing vaccines and treatment strategies against CVL. New methodologies for studying the immune response of dogs during Leishmania infection and after receiving vaccines and treatments against CVL would be useful. In this context, we used peripheral blood mononuclear cells (PBMCs) from healthy dogs to evaluate procedures related to (i) establishment of in vitro conditions of monocytes differentiated into macrophages infected with L. chagasi and (ii) purification procedures of T-cell subsets (CD4(+) and CD8(+)) using microbeads. Our data demonstrated that after 5 days of differentiation, macrophages were able to induce significant phagocytic and microbicidal activity after L. chagasi infection and also showed increased frequency of parasitism and a higher parasite load. Although N-acetyl-β-d-glucosaminidase (NAG) levels presented similar levels of macrophage culture and L. chagasi infection, a progressive decrease in myeloperoxidase (MPO) levels was a hallmark over 5 days of culture. High purity levels (>90%) of CD4 and CD8 T cells were obtained on a magnetic separation column. We concluded that monocytes differentiated into macrophages at 5 days and displayed an intermediate frequency of parasitism and parasite load 72 h after L. chagasi infection. Furthermore, the purification system using canine T-lymphocyte subsets obtained after 5 days of monocyte differentiation proved efficient for CD4 or CD8 T-cell purification (≥90%). The in vitro analysis using L. chagasi-infected macrophages and purified T cells presented a prospective methodology that could be incorporated in CVL vaccine and treatment studies that aim to analyze the microbicidal potential induced by specific CD4(+) and/or CD8(+) T cells.

In the studies presented here, dogs were vaccinated against Leishmania (Leishmania) chagasi challenge infection using a preparation of Leishmania braziliensis promastigote proteins and saponin as adjuvant (LBSap). Vaccination with LBSap induced a prominent type 1 immune response that was characterized by increased levels of interleukin (IL-) 12 and interferon gamma (IFN-γ) production by peripheral blood mononuclear cells (PBMC) upon stimulation with soluble vaccine antigen. Importantly, results showed that this type of responsiveness was sustained after challenge infection; at day 90 and 885 after L. chagasi challenge infection, PBMCs from LBSap vaccinated dogs produced more IL-12, IFN-γ and concomitant nitric oxide (NO) when stimulated with Leishmania antigens as compared to PBMCs from respective control groups (saponin, LB- treated, or non-treated control dogs). Moreover, transforming growth factor (TGF)-β decreased in the supernatant of SLcA-stimulated PBMCs in the LBSap group at 90 days. Bone marrow parasitological analysis revealed decreased frequency of parasitism in the presence of vaccine antigen. It is concluded that vaccination of dogs with LBSap vaccine induced a long-lasting type 1 immune response against L. chagasi challenge infection.