Adenoviruses with an RGD-4C modification of the fiber knob elicit a neutralizing antibody response but continue to allow enhanced gene delivery.
OBJECTIVE
The purpose of this study was to investigate the effect of preexisting neutralizing antibody (NAbs) in naive mice and the effect of induced NAbs in mice immunized with either an RGD or nonmodified Ad5 vector on the transduction efficiency of adenoviral vectors.


METHODS
BALB/c mice were immunized with Ad5LucRGD, with the unmodified Ad5Luc1, or with Opti-MEM intraperitoneally (ip) from one to three times. Sera were collected on day 27 and serially diluted to block Ad5Luc1 or Ad5LucRGD prior to infection of SKOV3.ip1 human ovarian carcinoma cells with these same vectors. Forty-eight hours post Ad infection, a luciferase assay was performed to determine the titer of NAbs.


RESULTS
Luciferase assay data showed that the gene transfer efficacy of Ad5LucRGD was 1.56-fold higher than Ad5Luc1 in the presence of serum from naive mice. In the presence of serum from Ad5Luc1-challenged mice, the transduction efficiency of Ad5LucRGD was 3.27-fold higher (single challenge) and 4.2-fold higher (triple challenge) than Ad5Luc1. In the presence of serum from Ad5LucRGD-challenged mice, the transduction efficiency of Ad5LucRGD was 2.24-fold higher (single challenge) and 2.53-fold higher (triple challenge) than Ad5Luc1.


CONCLUSIONS
The RGD-modified human Ad vectors appear to be less recognizable than unmodified Ad to preexisting NAbs in mouse models. RGD-modified Ad vectors also appear to elicit a relatively lower level of NAbs that may also contribute to the higher gene transduction efficiency of these modified vectors. Therefore, RGD-modified Ad vectors may be reagents of clinical utility in the context of preformed anti-Ad immunity and in the setting of repetitive dosing.
Wang
Minghui
M
Department of Medicine, Division of Human Gene Therapy, University of Alabama at Birmingham, 618 20th Street South, OHB-538, Birmingham, AL 35294, USA.
Hemminki
Akseli
A
Siegal
Gene P
GP
Barnes
Mack N
MN
Dmitriev
Igor
I
Krasnykh
Victor
V
Liu
Bin
B
Curiel
David T
DT
Alvarez
Ronald D
RD
D000256:Adenoviridae / Q000235:genetics* / Q000276:immunology*; D000818:Animals; D000906:Antibodies / Q000097:blood / Q000276:immunology; D000917:Antibody Formation; D036022:Capsid Proteins / Q000235:genetics* / Q000276:immunology*; D005260:Female; D018014:Gene Transfer Techniques; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009842:Oligopeptides / Q000235:genetics / Q000276:immunology*; D010051:Ovarian Neoplasms / Q000235:genetics / Q000276:immunology / Q000628:therapy / Q000821:virology
D000906:Antibodies; D036022:Capsid Proteins; D009842:Oligopeptides; C018315:hexon capsid protein, Adenovirus; C047981:arginyl-glycyl-aspartic acid; D008156:Luciferases