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Journal of Virology, May 2001, p. 4792-4801, Vol. 75, No. 10
Institute for Human Gene Therapy and
Department of Molecular and Cellular Engineering, University of
Pennsylvania, Philadelphia, Pennsylvania 19104,1
and Division of Pharmaceutics, The University of Texas at
Austin College of Pharmacy, Austin, Texas 787122
Received 31 October 2000/Accepted 2 February 2001
Most of the early gene therapy trials for cystic fibrosis have been
with adenovirus vectors. First-generation viruses with E1a and E1b
deleted are limited by transient expression of the transgene and
substantial inflammatory responses. Gene transfer is also significantly
curtailed following a second dose of virus. In an effort to reduce
adenovirus-associated inflammation, capsids of first-generation vectors
were modified with various activated monomethoxypolyethylene glycols.
Cytotoxic T-lymphocyte production was significantly reduced in C57BL/6
mice after a single intratracheal administration of modified vectors,
and length of gene expression was extended from 4 to 42 days. T-cell
subsets from mice exposed to the conjugated vectors demonstrated a
marked decrease in Th1 responses and slight enhancement of Th2
responses compared to animals dosed with native virus. Neutralizing
antibodies (NAB) against adenovirus capsid proteins were reduced in
serum and bronchoalveolar lavage fluid of animals after a single dose
of modified virus, allowing significant levels of gene expression upon
rechallenge with native adenovirus. Modification with polyethylene
glycol (PEG) also allowed substantial gene expression from the new
vectors in animals previously immunized with unmodified virus. However, gene expression was significantly reduced after two doses of the same
PEG-conjugated vector. Alternating the activation group of PEG between
doses did produce significant gene expression upon readministration.
This technology in combination with second-generation or
helper-dependent adenovirus could produce dosing strategies which
promote successful readministration of vector in clinical trials and
marked expression in patients with significant anti-adenovirus NAB
levels and reduce the possibility of immune reactions against viral
vectors for gene therapy.
0022-538X/01/$04.00+0 DOI: 10.1128/JVI.75.10.4792-4801.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
"Stealth" Adenoviruses Blunt Cell-Mediated and Humoral
Immune Responses against the Virus and Allow for Significant
Gene Expression upon Readministration in the Lung
*
Corresponding author. Mailing address for James M. Wilson: 204 Wistar Institute, 3601 Spruce St., Philadelphia, PA
19104-4268. Phone: (215) 898-3000. Fax: (215) 898-6588. E-mail:
wilsonjm{at}mail.med.upenn.edu. Mailing address
for Maria A. Croyle: The University of Texas at Austin College of
Pharmacy, Division of Pharmaceutics, PHR 4.214D, Austin, TX 78712. Phone: (512) 471-1972. Fax: (512) 471-7474. E-mail:
macroyle{at}mail.utexas.edu.
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