Antigenicity and immunogenicity of phage library-selected peptide mimics of the major surface proteophosphoglycan antigens of Entamoeba histolytica.
Entamoeba histolytica is the protozoan parasite responsible for intestinal amoebiasis and amoebic liver abscess, which cause significant morbidity and mortality in many countries of the world. Proteophosphoglycans (PPGs, also known as lipophosphoglycans, LPGs, or lipopeptidophosphoglycans, LPPGs) represent dominant surface components of E. histolytica. Passive immunization with a monoclonal antibody (EH5) directed against these components protected SCID mice from amoebic liver abscess, so PPGs might be regarded as vaccine candidates; however, their structure is very complex and only known in part. They are glycosylphosphatidylinositol-linked polypeptides of unknown sequence carrying glycan side-chains linked to serine residues via phosphodiester bonds. In order to identify peptide mimics of the E. histolytica PPG antigens, we screened six different phage-displayed random peptide libraries with the antibody EH5. Various peptide mimics of different length were identified and, in all the peptides, a distinct consensus sequence Gly-Thr-His-Pro-X-Leu could be identified. The phages strongly bound to the antibody, and the natural antigen inhibited binding of the phages to antibody EH5. In addition, several of the phages induced a significant immunoglobulin G response against amoebic antigens in immunized mice.
Melzer
Helen
H
Division of Specific Prophylaxis and Tropical Medicine, Department of Pathophysiology, Vienna, Austria.
Fortugno
Paola
P
Mansouri
Erfan
E
Felici
Franco
F
Marinets
Alexandra
A
Wiedermann
Gerhard
G
Kollaritsch
Herwig
H
Von Specht
Bernd-Ulrich
BU
Duchêne
Michael
M
D020816:Amino Acid Motifs; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000953:Antigens, Protozoan / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*; D000954:Antigens, Surface / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D001667:Binding, Competitive; D004748:Entamoeba histolytica / Q000254:growth & development / Q000276:immunology* / Q000648:ultrastructure; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000032:analysis / Q000276:immunology; D005455:Fluorescent Antibody Technique; D006028:Glycosphingolipids / Q000276:immunology; D007114:Immunization; D008018:Life Cycle Stages; D051379:Mice; D019151:Peptide Library; D011509:Proteoglycans / Q000737:chemistry / Q000276:immunology*; D020539:Sequence Analysis, Protein
D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan; D000954:Antigens, Surface; D000939:Epitopes; D006028:Glycosphingolipids; D019151:Peptide Library; D011509:Proteoglycans; C008290:lipophosphonoglycan