Characterization and localization of saposin-like protein-2 (SAP-2) in Fasciola gigantica

Parasitol Res. 2011 Jun;108(6):1493-500. doi: 10.1007/s00436-010-2201-7. Epub 2010 Dec 29.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Helminth / immunology
  • Cecum / chemistry
  • Cloning, Molecular
  • Epithelial Cells / chemistry
  • Fasciola / immunology
  • Fasciola / metabolism*
  • Fascioliasis / immunology
  • Fascioliasis / parasitology
  • Fatty Acid-Binding Proteins / genetics
  • Fatty Acid-Binding Proteins / isolation & purification
  • Fatty Acid-Binding Proteins / metabolism*
  • Fluorescent Antibody Technique
  • Gene Library
  • In Situ Hybridization
  • Polymerase Chain Reaction
  • RNA, Messenger / analysis
  • Rabbits
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Saposins / genetics
  • Saposins / isolation & purification
  • Saposins / metabolism*

Substances

  • Antibodies, Helminth
  • Fatty Acid-Binding Proteins
  • RNA, Messenger
  • Recombinant Proteins
  • Saposins