**Acknowledgements**

Effective immunization requires the presentation of the antigen by proper APCs to mount a strong immune response and develop immunological memory, as well as it entails antigen persistence. As described previously, live vaccines produce more robust immune responses than dead parasites or defined protein or peptides but they represent an important health risk, mainly in immunosuppressed people. Furthermore, the immune response developed against live *Leishmania infantum* strains that display differences in infectivity is also unique and characteristic of each strain, being infectivity related with a stronger induction of an immune

In this chapter, we have updated the main aspects to consider when a vaccination study against *Leishmania* is planned. We aimed to show that vaccination is an effective way, and hopefully a soon reality, to prevent the spread of leishmaniasis, limiting the outcome of the disease and avoiding the parasite transmission. While successful research is close, many efforts are still needed for achieving an efficient human vaccine for leishmaniasis accessible to everyone in

response, as showed by our experimental data.

298 Leishmaniasis - Trends in Epidemiology, Diagnosis and Treatment

need.

**5. Abbreviations**

**IL** interleukin

**NO** nitric oxide

**ALM** autoclaved *Leishmania major*

**MCL** mucocutaneous leishmaniasis

**MPL** purified derivative of the monophosphoryl lipid A

**PAMP** pathogen-associated molecular pattern

**SE** squalene-based oil-in-water stable emulsion

**PBMCs** peripheral blood mononuclear cells

**APCs** antigen presenting cells

**CL** cutaneous leishmaniasis

**TCM** central memory T cell

**TEM** effector memory T cell

**TCR** T cell receptor

**TLR** Toll-like receptor

**VL** visceral leishmaniasis

**ZVL** zoonotic visceral leishmaniasis

We thank Doctor Maria da Luz Duarte from São Marcos Hospital, Braga, Portugal, for kindly providing us the skin sample infected with HL strain of *L. infantum*. We thank Joana Tavares from the Parasite Disease Group, IBMC, Porto, Portugal, for the isolation of HL strain and preparation of live stocks and Carmen Chicharro from WHO Collaborating Center for Leishmaniasis, National Center of Microbiology, Instituto de Salud Carlos III, Majadahonda, Spain, for analyzing its zymodeme. We thank Ricardo Silvestre and Mariana Resende from the Parasite Disease Group, IBMC, Porto, Portugal, for the help in animal experiments and flow cytometry analysis.

This work was funded by FEDER funds through the Operational Competitiveness Programme – COMPETE and by National Funds through FCT – Fundação para a Ciência e a Tecnologia under the projects FCOMP-01-0124-FEDER-019648 (PTDC/BIA-MIC/118644/2010) and FCOMP-01-0124-FEDER-011058 (PTDC/SAU-FCF/101017/2008) as well as the MICINN's project number PIM2010-ENI00627. The research leading to these results has also received funding from the European Community's Seventh Framework Programme under grant agreement No.603181 (Project MuLeVaClin).
