Molecular characterization of Ancylostoma ceylanicum Kunitz-type serine protease inhibitor: evidence for a role in hookworm-associated growth delay

Infect Immun. 2004 Apr;72(4):2214-21. doi: 10.1128/IAI.72.4.2214-2221.2004.

Abstract

Hookworm infection is a major cause of iron deficiency anemia and malnutrition in developing countries. The Ancylostoma ceylanicum Kunitz-type inhibitor (AceKI) is a 7.9-kDa broad-spectrum inhibitor of trypsin, chymotrypsin, and pancreatic elastase that has previously been isolated from adult hookworms. Site-directed mutagenesis of the predicted P1 inhibitory reactive site amino acid confirmed the role of Met(26) in mediating inhibition of the three target serine proteases. By using reverse transcription-PCR, it was demonstrated that the level of AceKI gene expression increased following activation of third-stage larvae with serum and that the highest level of expression was reached in the adult stage of the parasite. Immunohistochemistry studies performed with polyclonal immunoglobulin G raised against recombinant AceKI showed that the inhibitor localized to the subcuticle of the adult hookworm, suggesting that it has a potential in vivo role in neutralizing intestinal proteases at the surface of the parasite. Immunization with recombinant AceKI was shown to confer partial protection against hookworm-associated growth delay without a measurable effect on anemia. Taken together, the data suggest that AceKI plays a role in the pathogenesis of hookworm-associated malnutrition and growth delay, perhaps through inhibition of nutrient absorption in infected hosts.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Ancylostoma / genetics
  • Ancylostoma / growth & development
  • Ancylostoma / metabolism
  • Ancylostoma / pathogenicity*
  • Ancylostomiasis / parasitology
  • Ancylostomiasis / physiopathology
  • Ancylostomiasis / prevention & control*
  • Animals
  • Antibodies, Helminth / blood
  • Cricetinae
  • Helminth Proteins / genetics
  • Helminth Proteins / immunology
  • Helminth Proteins / metabolism
  • Immunization
  • Life Cycle Stages
  • Male
  • Malnutrition / parasitology
  • Malnutrition / physiopathology
  • Malnutrition / prevention & control*
  • Mesocricetus
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Organ Specificity
  • Recombinant Proteins / genetics
  • Recombinant Proteins / immunology
  • Serine Proteinase Inhibitors / genetics*
  • Serine Proteinase Inhibitors / immunology
  • Serine Proteinase Inhibitors / metabolism
  • Vaccines / administration & dosage
  • Vaccines / genetics
  • Vaccines / immunology

Substances

  • Antibodies, Helminth
  • Helminth Proteins
  • Recombinant Proteins
  • Serine Proteinase Inhibitors
  • Vaccines