title: An enzymatically inactivated hemoglobinase from Necator americanus induces neutralizing antibodies against multiple hookworm species and protects dogs against heterologous hookworm infection.
abstract: Hookworms digest hemoglobin from erythrocytes via a proteolytic cascade that begins with the aspartic protease, APR-1. Ac-APR-1 from the dog hookworm, Ancylostoma caninum, protects dogs against hookworm infection via antibodies that neutralize enzymatic activity and interrupt blood-feeding. Toward developing a human hookworm vaccine, we expressed both wild-type (Na-APR-1(wt)) and mutant (Na-APR-1(mut)-mutagenesis of the catalytic aspartic acids) forms of Na-APR-1 from the human hookworm, Necator americanus. Refolded Na-APR-1(wt) was catalytically active, and Na-APR-1(mut) was catalytically inactive but still bound substrates. Vaccination of canines with Na-APR-1(mut) and heterologous challenge with A. caninum resulted in significantly reduced parasite egg burdens (P=0.034) and weight loss (P=0.022). Vaccinated dogs also had less gut pathology, fewer adult worms, and reduced blood loss compared to controls but these did not reach statistical significance. Vaccination with Na-APR-1(mut) induced antibodies that bound the native enzyme in the parasite gut and neutralized enzymatic activity of Na-APR-1(wt) and APR-1 orthologues from three other hookworm species that infect humans. IgG1 against Na-APR-1(mut) was the most prominently detected antibody in sera from people resident in high-transmission areas for N. americanus, indicating that natural boosting may occur in exposed humans. Na-APR-1(mut) is now a lead antigen for the development of an antihematophagy vaccine for human hookworm disease.
authors.affiliation: Division of Infectious Diseases, Queensland Institute of Medical Research and The Australian Centre for Vaccine Development, Brisbane, Australia.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Pearson
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Bethony
authors.forename: Darren A
authors.initials: DA
authors.lastname: Pickering
authors.forename: Luciana M
authors.initials: LM
authors.lastname: de Oliveira
authors.forename: Amar
authors.initials: A
authors.lastname: Jariwala
authors.forename: Helton
authors.initials: H
authors.lastname: Santiago
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Miles
authors.forename: Bin
authors.initials: B
authors.lastname: Zhan
authors.forename: Desheng
authors.initials: D
authors.lastname: Jiang
authors.forename: Najju
authors.initials: N
authors.lastname: Ranjit
authors.forename: Jason
authors.initials: J
authors.lastname: Mulvenna
authors.forename: Leon
authors.initials: L
authors.lastname: Tribolet
authors.forename: Jordan
authors.initials: J
authors.lastname: Plieskatt
authors.forename: Tracey
authors.initials: T
authors.lastname: Smith
authors.forename: Maria Elena
authors.initials: ME
authors.lastname: Bottazzi
authors.forename: Kathryn
authors.initials: K
authors.lastname: Jones
authors.forename: Brian
authors.initials: B
authors.lastname: Keegan
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hotez
authors.forename: Alex
authors.initials: A
authors.lastname: Loukas
mesh_terms: D000723:Ancylostomatoidea / Q000276:immunology; D000818:Animals; D000909:Antibodies, Helminth / Q000008:administration & dosage / Q000627:therapeutic use*; D003546:Cysteine Endopeptidases / Q000276:immunology*; D004285:Dogs; D006725:Hookworm Infections / Q000517:prevention & control* / Q000628:therapy; D006801:Humans; D007422:Intestines / Q000469:parasitology; D017221:Necator americanus / Q000276:immunology*; D016896:Treatment Outcome; D014611:Vaccination / Q000379:methods; D014612:Vaccines / Q000494:pharmacology / Q000627:therapeutic use; D015431:Weight Loss
chemical_list: D000909:Antibodies, Helminth; D014612:Vaccines; D003546:Cysteine Endopeptidases