Lipophosphoglycan of Leishmania major that vaccinates against cutaneous leishmaniasis contains an alkylglycerophosphoinositol lipid anchor.

Abstract

The major cell surface glycoconjugate of Leishmania major, a putative parasite receptor for macrophages, is a lipophosphoglycan containing 81.6% (wt/wt) carbohydrate, 17.0% (wt/wt) phosphate, and 1.4% (wt/wt) lipid. It has been purified to homogeneity by hydrophobic chromatography and consists of a polydisperse family of molecules with Mr 5000-40,000. It contains galactose, mannose, glucose, arabinose, glucosamine, and inositol in the molar ratio of 51:21:5:6:1:1. The lipophosphoglycan has a complex structure, consisting mainly of tri-and tetrasaccharide units linked by phosphodiester bonds, which are cleaved by HF hydrolysis. The phosphate groups are located on the 6-hydroxyl of both galactose and mannose residues. The lipophosphoglycan is anchored to the parasite surface by a 1-O-alkyl-snglycero-3-phosphoinositol moiety. This conclusion is supported by analysis of the products of nitrous acid deamination, HF hydrolysis, and Staphylococcus aureus phosphatidylinositol specific-phospholipase C treatment. The 24:0 and 26:0 alkyl chains accounted for 93% of the ether-linked fatty acids in the lipid anchor. The results are also consistent with a glycosidic linkage between the inositol and a non-N-acetylated glucosamine residue. The lipophosphoglycan membrane anchor shares limited structural homology with the glycosylphosphatidylinositol anchors of several eukaryotic proteins, indicating that this type of membrane anchor is not limited to proteins. Vaccination of mice with the purified L. major lipophosphoglycan in liposomes induced resistance against cutaneous leishmaniasis.Essential for the establishment of infection by the obligatory intramacrophage parasite Leishmania major are four sequential events: recognition, intracellular entry, survival, and replication (1,2). A family of lipoglycoconjugates on the cell surface of L. major, the etiological agent of cutaneous leishmaniasis, are putative parasite recognition molecules for macrophages of the mammalian host (3). A molecule with similar chemical properties has been isolated from Leishmania donovani, the etiological agent of visceral leishmaniasis, and partially characterized as a lipophosphoglycan (LPG) containing mannose, galactose, and phosphate (4, 5). The presence of a hydrophobic lipid moiety in the Leishmania LPGs was indicated by their amphipathic properties and by biosynthetic labeling with fatty acids (4, 6, 7). This lipid could be removed by treatment of LPG with phospholipase C (3). These glycoconjugates are part of a polymorphic family of similar but antigenically distinct molecules present in all Leishmania species (6,8) and have formed the basis for the classification of Leishmania.The localization of the L. major LPG on the surface of both the promastigote and infected macrophage (6) made it an attractive candidate for a vaccine. This was confirmed by studies showing that L. major LPG, immunoaffinity purified from detergent extracts by using the monoclonal antibody WIC-79.3, protected mice against cutaneous leishmaniasis (9).In this ...

The glycosylphosphatidylinositol anchor of the trypomastigote‐specific Tc‐85 glycoprotein from Trypanosoma cruzi

“…In other glycosyl-PtdIns anchors the alkylglycerol is usually acylated by a fatty acid (Ferguson, 1992). A lysoalkylglycerol was determined in the lipophosphoglycan of Leishmania species (Orlandi and Turco, 1987;McConville et al, 1987) and in the glycoinositolphospholipids together with alkylacylglycerol (McConville et al, 1990).…”

Molecular and Antigenic Characterization of the Leishmania (Viannia) panamensis Kinetoplastid Membrane Protein-11

“…Fax: + 57-4-511.4559 Received 29 October 1997 Accepted 15 January 1998 Control of leishmaniasis in the American continent is particularly complicated due to the fast evolving variety of Leishmania parasites and the complexity in their epidemiological patterns (Grimaldi & Tesh 1993). Recent attempts to develop molecularly defined vaccines for leishmaniasis have focused on major parasite cell surface molecules, including the metalloproteinase GP63, the promastigote surface antigen complex (PSA) and the lipophosphoglycans (LPG) (McConville et al 1987, Chang et al 1990, Burns et al 1991. For reasons such as its abundance on promastigotes and its important physiological role in parasitemacrophage interactions (Turco & Descoteaux 1992), the latter was considered an attractive vaccine candidate.…”

“…For reasons such as its abundance on promastigotes and its important physiological role in parasitemacrophage interactions (Turco & Descoteaux 1992), the latter was considered an attractive vaccine candidate. In early works, it has been demonstrated that immunization with LPG might confer immunoprotectivity in mice (Handman & Mitchell 1985, McConville et al 1987, Russell & Alexander 1988 and that peripheral blood mononuclear cells from leishmaniasis patients were strongly stimulated to proliferate in response to LPG (McConville et al 1987, Jaffe et al 1990, Mendoca et al 1991. However, it could be recently shown that T-cell stimulation associated with protective immunity elicited in mice, was due to a tightly associated small protein in the LPG fraction which was recently renamed as the kinetoplastid membrane pro-tein-11 (KMP-11) (Jardim et al 1991, Stebeck et al 1995.…”

L3T4 T cells promoting susceptibility to murine cutaneous leishmaniasis express the surface marker Ly‐24 (Pgp‐1)

“…This concept is supported by the finding that a lipophosphoglycan (LPG) isolated from L. mtJjor induces resistance to Ieishmania! infection [44), whereas a carbohydrate (CHO) produced by enzymatic cleavage of the same LPG can exacerbate subsequent disease [45]. lt is conceivable that LPG-specific L3T4+ cells activate L. majorinfected macrophages for killing of intracellular organisms, resulting in the resolution of disease, whereas activation of CHO-specific L3T4+ cells may result in further inflammation and recruitment of immature macrophages that serve as targets of infection [46].…”