This veterinary vaccine

protects 98% of vaccinated dogs and blocks the transmission of the disease in endemic areas [1], [2] and [3]. In the Americas and the Mediterranean, visceral leishmaniasis is an immunosuppressive zoonotic disease transmitted from dogs to humans through the byte of a sand fly vector [4]. The disease is fatal in humans and dogs if untreated and treatment is highly toxic and not always efficient. The epidemiological control of the disease see more includes the treatment of human cases, insect vector control with insecticides and the culling of seropositive/infected dogs. Human or canine vaccines are expected to be effective tools for the prophylactic control of epidemics [5]. The recent canine vaccinations with the Leishmune® vaccine in Brazil reduced the incidence of human cases, human deaths and dog prevalence of visceral leishmaniasis in endemic areas [6]. In districts where the vaccinations occurred the canine and human incidence decreased or achieved a stabilized

plateau while in non-vaccinated districts the incidences rose [6]. Leishmune® is the FML-saponin vaccine [1], [3], [7] and [8] composed of the FML (Fucose Mannose ligand) antigen [9], a complex glycoproteic fraction of Leishmania donovani, and a Quillaja saponaria saponin adjuvant (Riedel de Haën-Sigma) [revised in 3]. The main active components of the Leishmune® adjuvant are the well known QS21 saponin and the two deacylated SCR7 cell line saponins that only differ from the QS21 due to the absence of the hydrophobic moiety [10]. Saponins are a structurally diverse class of natural compounds occurring in several plant species. According to previous reports the most common components of the saponin core are the triterpenoid and steroid aglycones to which carbohydrate chains

are attached [11]. They exhibit from one to three straight or branched sugar chains Parvulin which most often include d-glucose, l-rhamnose, d-galactose, d-glucuronic acid, l-arabinose, d-xylose or d-fucose. The sugar chain can contain from one or more monosaccharide residues, and is usually attached at the C-3 of the triterpene [11]. The correlation between structure and function of saponins has been the focus of intensive research in order to define the essential moieties for the development of the adjuvant activity [10], [11], [12], [13], [14] and [15]. Saponins with steroid but not with triterpene aglycones are considered to be the most hemolytic [12] and [16]. Alternatively, the hemolytic or membranolytic activity has been attributed to the oligosaccharide moiety of saponins [13], [17], [18], [19], [20], [21] and [22]. And the saponins with two glycidic chains attached to the aglycone, called bidesmosidic [10] and [14], have been shown to be more immunogenic than the monodesmosidic ones [14]. In the QS21 saponin of Q.