Leishmaniasis, a vector-borne disease caused by obligate intramacrophage protozoa, threatens 350 million people in 98 countries around the world. There are already 12 million infected people worldwide and two million new cases occur annually. Leishmaniasis has three main clinical presentations: cutaneous (CL), mucosal (ML), and visceral (VL). It is considered an opportunistic, infectious disease and the HIV-leishmaniasis correlation is well known. Antimonial compounds are used as first-line treatment drugs, but their toxicity, which can be extremely high, leads to a number of undesirable side effects and resultant failure of the patients to adhere to treatment. There is also a reported increase in Leishmania sp. resistance to these drugs. Nanotechnology has emerged as an attractive alternative because of its improved bioavailability and lower toxicity, and other characteristics that help to relieve the burden of this disease. In this review we will present some of the recent advances in the nanotechnological research regarding the treatment of leishmaniasis. The preclinical results regarding the approaches for a biomedical treatment of the disease have been encouraging, but further efforts will still be necessary for this therapy to have greater clinical applicability in humans.

Background: Although the genome sequence of the protozoan parasite Leishmania major was determined several years ago, the knowledge of its transcriptome was incomplete, both regarding the real number of genes and their primary structure. Results: Here, we describe the first comprehensive transcriptome analysis of a parasite from the genus Leishmania. Using high-throughput RNA sequencing (RNA-seq), a total of 10285 transcripts were identified, of which 1884 were considered novel, as they did not match previously annotated genes. In addition, our data indicate that current annotations should be modified for many of the genes. The detailed analysis of the transcript processing sites revealed extensive heterogeneity in the spliced leader (SL) and polyadenylation addition sites. As a result, around 50% of the genes presented multiple transcripts differing in the length of the UTRs, sometimes in the order of hundreds of nucleotides. This transcript heterogeneity could provide an additional source for regulation as the different sizes of UTRs could modify RNA stability and/or influence the efficiency of RNA translation. In addition, for the first time for the Leishmania major promastigote stage, we are providing relative expression transcript levels. Conclusions: This study provides a concise view of the global transcriptome of the L. major promastigote stage, providing the basis for future comparative analysis with other development stages or other Leishmania species.