title: Leishmania: amastigotes synthesize conserved secretory acid phosphatases during human infection.
abstract: Leishmania donovani is the major causative agent of Old World human visceral leishmaniasis (VL). In vitro, both promastigotes and axenic amastigotes of L. donovani constitutively secrete soluble acid phosphatases (SAcPs), which contain conserved antigenic epitopes. These SAcPs are the most abundant and best characterized secretory proteins of this parasite. The aim of this study was to determine whether this enzyme was produced by intracellular amastigotes during the course of human infection. To that end, sera from acutely infected leishmaniasis patients were tested for anti-SAcP antibodies using L. donovani promastigote culture supernatants. Our results showed that VL patient sera from different endemic foci immunoprecipitated parasite SAcP enzyme activity. Further, these VL patient sera recognized the 110- and 130-kDa SAcPs in both Western blots and radioimmunoprecipitation assays. Results of tunicamycin experiments demonstrated that VL patient anti-SAcP antibodies were directed against the polypeptide backbone of the parasite SAcPs. In addition, both radiolabeled L. donovani SAcPs and native enzyme activities were immunoprecipitated by sera from patients with various forms of cutaneous leishmaniasis. Together, these studies demonstrate that Leishmania amastigotes produce SAcPs during the course of human infections.
authors.affiliation: Cell Biology Section, Laboratory of Parasitic Diseases, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0425, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Ellis
authors.forename: A M
authors.initials: AM
authors.lastname: Shakarian
authors.forename: D M
authors.initials: DM
authors.lastname: Dwyer
mesh_terms: D000135:Acid Phosphatase / Q000096:biosynthesis* / Q000737:chemistry / Q000276:immunology; D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D015153:Blotting, Western; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007893:Leishmania donovani / Q000201:enzymology* / Q000276:immunology; D016773:Leishmaniasis, Cutaneous / Q000201:enzymology / Q000276:immunology; D007898:Leishmaniasis, Visceral / Q000201:enzymology* / Q000276:immunology; D051379:Mice; D008970:Molecular Weight; D011233:Precipitin Tests; D011817:Rabbits
chemical_list: D000913:Antibodies, Protozoan; D007106:Immune Sera; D000135:Acid Phosphatase