title: Neutralizing antibodies to the hookworm hemoglobinase Na-APR-1: implications for a multivalent vaccine against hookworm infection and schistosomiasis.
abstract: The aspartic protease of Necator americanus, Na-APR-1, is a vaccine antigen that induces antibodies that neutralize hemoglobin proteolysis in the gut of the worm. To define the epitopes recognized by these antibodies, monoclonal antibodies (mAbs) were raised and assessed for neutralizing activity. Three immunoglobulin (Ig) G1 mAbs bound to the intestine of N. americanus and inhibited Na-APR-1 enzymatic activity. Overlapping fragments of Na-APR-1 were expressed, and one (APR-1/5B) was recognized by all 3 mAbs; the epitope was further characterized as AGPKAQVEAIQKY (A(291)Y). This same peptide with a Phe/Tyr(303) substitution was recognized by mAbs in APR-1 orthologues from Ancylostoma species hookworms. IgG from humans infected with hookworms did not recognize A(291)Y but, rather, recognized the S(107)L epitope. APR-1/5B was fused to other helminth vaccine antigens, including Schistosoma mansoni Sm-TSP-2 and N. americanus Na-GST-1; antibodies against both chimeras neutralized the enzymatic activity of Na-APR-1. These findings support the incorporation of Na-APR-1 into a multivalent vaccine against hookworm and/or schistosomiasis.
authors.affiliation: Division of Infectious Diseases, Queensland Institute of Medical Research, The Australian Centre for Vaccine Development, Queensland, Australia.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Pearson
authors.forename: Darren A
authors.initials: DA
authors.lastname: Pickering
authors.forename: Leon
authors.initials: L
authors.lastname: Tribolet
authors.forename: Leanne
authors.initials: L
authors.lastname: Cooper
authors.forename: Jason
authors.initials: J
authors.lastname: Mulvenna
authors.forename: Luciana M
authors.initials: LM
authors.lastname: Oliveira
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Bethony
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hotez
authors.forename: Alex
authors.initials: A
authors.lastname: Loukas
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D057055:Aspartic Acid Proteases / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D004306:Dose-Response Relationship, Immunologic; D000939:Epitopes; D006725:Hookworm Infections / Q000517:prevention & control*; D007074:Immunoglobulin G / Q000276:immunology; D051379:Mice; D008969:Molecular Sequence Data; D017221:Necator americanus / Q000201:enzymology*; D011487:Protein Conformation; D012552:Schistosomiasis / Q000517:prevention & control*; D014612:Vaccines / Q000276:immunology*; D014614:Vaccines, Synthetic / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D007074:Immunoglobulin G; D014612:Vaccines; D014614:Vaccines, Synthetic; D057055:Aspartic Acid Proteases