title: Molecular cloning of a member of the Fasciola hepatica saposin-like protein family.
abstract: A 436-bp complementary DNA (cDNA) was isolated from an adult Fasciola hepatica cDNA expression library by screening with the serum from a rabbit infected with F. hepatica for 4 wk. The deduced amino acid sequence encoded by this cDNA is an 11.5-kDa polypeptide that has significant homology to F. hepatica NK-lysin protein, to several members of saposin-like or NK-lysin protein families, as well as 3 amoebapore precursors of Entamoeba histolytica. The most striking feature observed within this protein, denoted FhSAP-2, is the presence of 6 conserved cysteine residues arranged within 5 amphipathic alpha-helical domains and the presence of 7 hydrophobic residues in strictly conserved positions. Using enzyme-linked immunosorbent assay it was found that rFhSAP-2 is highly reactive with sera from rabbits infected with F. hepatica for 2-14 wk as well as with sera from humans with chronic fascioliasis. An anti-rFhSAP-2 rabbit antiserum reacted with F. hepatica excretory-secretory antigens by Western blot, revealing a major 11.5-kDa and 2 minor 46- and 67-kDa antigenic polypeptides. This suggests that FhSAP-2 may be an antigen released from cytoplasmic storage granules present within F. hepatica parasites. rFhSAP-2 also exhibits a strong lytic activity on human erythrocytes and peripheral blood mononuclear cells. This suggests that cell lysis could be 1 of the biological functions of this protein.
authors.affiliation: Laboratory of Parasite Immunology and Pathology, Department of Pathology and Laboratory Medicine (Suite 617-A), University of Puerto Rico School of Medicine, P.O. Box 365067, San Juan, PR 00936-5067, USA.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Espino
authors.forename: George V
authors.initials: GV
authors.lastname: Hillyer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D018509:DNA, Helminth / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay; D004912:Erythrocytes / Q000469:parasitology; D005210:Fasciola hepatica / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D005211:Fascioliasis / Q000469:parasitology*; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000469:parasitology; D008969:Molecular Sequence Data; D011510:Proteolipids / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D011663:Pulmonary Surfactants / Q000737:chemistry / Q000276:immunology; D018510:RNA, Helminth / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D049231:Saposins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D049128:Sphingolipid Activator Proteins
chemical_list: D018076:DNA, Complementary; D018509:DNA, Helminth; D006023:Glycoproteins; D015801:Helminth Proteins; D007106:Immune Sera; C093238:NK-lysin; C483345:PSAP protein, human; D011510:Proteolipids; D011663:Pulmonary Surfactants; D018510:RNA, Helminth; D012333:RNA, Messenger; D049231:Saposins; D049128:Sphingolipid Activator Proteins