Molecular characterization of Ancylostoma inhibitors of coagulation factor Xa. Hookworm anticoagulant activity in vitro predicts parasite bloodfeeding in vivo.
Bloodfeeding hookworms, which currently infect over a billion people in the developing world, are a leading cause of gastrointestinal hemorrhage and iron deficiency anemia. The major anticoagulant inhibitor of coagulation factor Xa has been identified from the hookworm parasite Ancylostoma ceylanicum using reverse transcription PCR and 3'-rapid amplification of cDNA ends. This is the first anticoagulant cloned from a hookworm species for which humans are recognized permissive hosts. Despite approximately 50% amino acid similarity, A. ceylanicum anticoagulant peptide 1 (AceAP1) is both immunologically and mechanistically distinct from AcAP5, its homologue isolated from the dog hookworm Ancylostoma caninum. Studies using plasma clotting times and single stage chromogenic assays of factor Xa activity have demonstrated that the recombinant AceAP1 protein is substantially less potent than AcAP5 and that soluble whole worm protein extracts of adult A. ceylanicum possess less anticoagulant activity than extracts of A. caninum. These values correlate with previously reported differences in bloodfeeding capabilities between these two species of hookworm, suggesting that factor Xa inhibitory activity is predictive of hookworm bloodfeeding capabilities in vivo. These fundamental differences in the mechanism of action and immunoreactivity of the major anticoagulant virulence factors from related Ancylostoma hookworm species may have significant implications for human vaccine development.
Harrison
Lisa M
LM
Yale Child Health Research Center, Division of Infectious Diseases, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06520-8081, USA.
Nerlinger
Andrew
A
Bungiro
Richard D
RD
Córdova
José Luis
JL
Kuzmic
Petr
P
Cappello
Michael
M
D000595:Amino Acid Sequence; D000818:Animals; D000925:Anticoagulants / Q000737:chemistry* / Q000494:pharmacology*; D001483:Base Sequence; D065427:Factor Xa Inhibitors; D015801:Helminth Proteins / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology; D007700:Kinetics; D008018:Life Cycle Stages; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011480:Protease Inhibitors / Q000737:chemistry / Q000494:pharmacology; D019105:Random Amplified Polymorphic DNA Technique; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D017183:Strongylida / Q000254:growth & development / Q000502:physiology*
D000925:Anticoagulants; D065427:Factor Xa Inhibitors; D015801:Helminth Proteins; D011480:Protease Inhibitors