Molecular characterization of Ancylostoma ceylanicum Kunitz-type serine protease inhibitor: evidence for a role in hookworm-associated growth delay.
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.
Chu
Daniel
D
Child Health Research Center, Department of Pediatrics, Yale School of Medicine, New Haven, Connecticut 06520-8081, USA.
Bungiro
Richard D
RD
Ibanez
Maureen
M
Harrison
Lisa M
LM
Campodonico
Eva
E
Jones
Brian F
BF
Mieszczanek
Juliusz
J
Kuzmic
Petr
P
Cappello
Michael
M
D000595:Amino Acid Sequence; D000722:Ancylostoma / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity*; D000724:Ancylostomiasis / Q000469:parasitology / Q000503:physiopathology / Q000517:prevention & control*; D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D006224:Cricetinae; D015801:Helminth Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D007114:Immunization; D008018:Life Cycle Stages; D008297:Male; D044342:Malnutrition / Q000469:parasitology / Q000503:physiopathology / Q000517:prevention & control*; D008647:Mesocricetus; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009928:Organ Specificity; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D015842:Serine Proteinase Inhibitors / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D014612:Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
D000909:Antibodies, Helminth; D015801:Helminth Proteins; D011994:Recombinant Proteins; D015842:Serine Proteinase Inhibitors; D014612:Vaccines