title: Decreased immune reactivity towards a knobless, affibody-targeted adenovirus type 5 vector.
abstract: In this study, a prototype Adenovirus type 5 (Ad5) vector deleted of the fiber knob domain and carrying an Affibody molecule as the targeting ligand showed decreased susceptibility to human pre-existing antibodies. This vector, Ad5/R7-Z(taq)Z(taq), has short fibers carrying seven shaft repeats, a non-native trimerization signal and an affibody molecule (Z(taq)) reactive to Taq polymerase. Ad5/R7-Z(taq)Z(taq) could be specifically targeted to 293 cells stably expressing membrane-bound anti-Z(taq) idiotypic affibody called Z(ztaq) (293Z(ztaq)). Sera from 50 blood donors were analyzed for neutralization activity (NA) against the parental Ad5/Fiwt vector and knobless Ad5/R7-Z(taq)Z(taq) on 293Z(ztaq) cells. Twenty-three sera had NA titers (> or =1:64) against Ad5/Fiwt (46%) and only two against Ad5/R7-Z(taq)Z(taq) (4%). Characterization of sera with NA titers showed that the knob domain is one of the targets of the antibodies. Neutralization assays using sera pre-adsorbed on knob and hexon proteins showed that the NA of the sera was carried mainly by anti-knob and anti-hexon antibodies, but in certain sera the anti-hexon antibodies represent the major population of the neutralizing antibodies (NAbs). Our results suggested that a combination of knob deletion and hexon switching could be an effective strategy for Ad vectors to better evade the anti-Ad NAbs.
authors.affiliation: Got-A-Gene AB, Ostra Kyviksvägen 18, Kullavik, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Myhre
authors.forename: P
authors.initials: P
authors.lastname: Henning
authors.forename: O
authors.initials: O
authors.lastname: Granio
authors.forename: A S
authors.initials: AS
authors.lastname: Tylö
authors.forename: P A
authors.initials: PA
authors.lastname: Nygren
authors.forename: S
authors.initials: S
authors.lastname: Olofsson
authors.forename: P
authors.initials: P
authors.lastname: Boulanger
authors.forename: L
authors.initials: L
authors.lastname: Lindholm
authors.forename: S-S
authors.initials: SS
authors.lastname: Hong
mesh_terms: D000260:Adenoviruses, Human / Q000235:genetics* / Q000276:immunology; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology*; D000956:Antigens, Viral / Q000235:genetics; D036022:Capsid Proteins / Q000235:genetics; D017353:Gene Deletion; D005818:Genetic Engineering; D005822:Genetic Vectors / Q000235:genetics* / Q000276:immunology*; D006801:Humans; D009500:Neutralization Tests; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D036022:Capsid Proteins; D011993:Recombinant Fusion Proteins; C018315:hexon capsid protein, Adenovirus