title: Characterization and localization of saposin-like protein-2 (SAP-2) in Fasciola gigantica.
abstract: Fasciola gigantica saposin-like protein-2 (FgSAP-2) belongs to a family of lipid-interacting proteins that are involved in the cytolysis of target cells. In this study, we have cloned and expressed FgSAP-2 and produced the antibody against this recombinant protein. Rabbit antiserum against rFgSAP-2 reacted with a similar native protein in the whole body extracts of the 4-week-old juvenile and adult stage, as well as a protein in their excretion-secretion, but not in the tegument. In situ hybridization and immunofluorescence detection revealed the presence of SAP-2 mRNA transcripts and proteins in the cecal epithelial cells of 4-week-old juvenile and adult parasites, but not in the metacercariae and newly excysted juveniles. Moreover, SAP-2 is present only in the cecal epithelial cells lining the distal part of the digestive tract, but not in the tegumental-type epithelium lining the proximal part of the digestive tract. The rFgSAP-2 reacted with antisera from rabbits infected with F. gigantica metacercariae collected at 5 weeks, but not at 2 weeks after infection. Anti-rFgSAP-2 did not exhibit any cross-reactivity with the other parasites' antigens, including Opisthorchis viverrini, Eurytrema pancreaticum, Cotylophoron cotylophorum, Fischoederius cobboldi, Gigantocotyle explanatum, Paramphistomum cervi, Setaria labiato-papillosa, and Haemonchus placei. This finding indicated that SAP-2 is a unique protein that is expressed only in late juvenile and adult F. gigantica, and it could be considered for immunodiagnostic and as a vaccine candidate for fasciolosis.
authors.affiliation: Department of Pathobiology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok, 10400, Thailand.
authors.forename: Pornanan
authors.initials: P
authors.lastname: Kueakhai
authors.forename: Krai
authors.initials: K
authors.lastname: Meemon
authors.forename: Narin
authors.initials: N
authors.lastname: Changklungmoa
authors.forename: Kulathida
authors.initials: K
authors.lastname: Chaithirayanon
authors.forename: Suda
authors.initials: S
authors.lastname: Riengrojpitak
authors.forename: Prasert
authors.initials: P
authors.lastname: Sobhon
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000276:immunology; D002432:Cecum / Q000737:chemistry; D003001:Cloning, Molecular; D004847:Epithelial Cells / Q000737:chemistry; D005209:Fasciola / Q000276:immunology / Q000378:metabolism*; D005211:Fascioliasis / Q000276:immunology / Q000469:parasitology; D050556:Fatty Acid-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D015723:Gene Library; D017403:In Situ Hybridization; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D049231:Saposins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000909:Antibodies, Helminth; D050556:Fatty Acid-Binding Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D049231:Saposins