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Journal of Virology, August 1999, p. 6708-6714, Vol. 73, No. 8
Vector Technologies Group, Center for Gene Therapy, Chiron
Technologies, San Diego, California 92121,1 and
Department of Virology and Immunology, Southwest Foundation for
Biomedical Research, San Antonio, Texas 782272
Received 23 February 1999/Accepted 10 May 1999
The ability to deliver genes as therapeutics requires an
understanding of the vector pharmacokinetics similar to that required for conventional drugs. A first question is the half-life of the vector
in the bloodstream. Retroviral vectors produced in certain human cell
lines differ from vectors produced in nonhuman cell lines in being
substantially resistant to inactivation in vitro by human serum
complement (F. L. Cosset, Y. Takeuchi, J. L. Battini, R. A. Weiss, and M. K. Collins, J. Virol. 69:7430-7436, 1995). Thus, use of human packaging cell lines (PCL) may produce vectors with
longer half-lives, resulting in more-efficacious in vivo gene therapy.
However, survival of human PCL-produced vectors in vivo following
systemic administration has not been explored. In this investigation,
the half-lives of retroviral vectors packaged by either canine D17 or
human HT1080 PCL were measured in the bloodstreams of macaques and
chimpanzees. Human PCL-produced vectors exhibited significantly higher
concentrations of circulating biologically active vector at the
earliest time points measured (>1,000-fold in chimpanzees), as well as
substantially extended half-lives, compared to canine PCL-produced
vectors. In addition, the circulation half-life of human PCL-produced
vector was longer in chimpanzees than in macaques. This was consistent
with in vitro findings which demonstrated that primate serum
inactivation of vector produced from human PCL increased with
increasing phylogenetic distance from humans. These results establish
that in vivo retroviral vector half-life correlates with in vitro
resistance to complement. Furthermore, these findings should influence
the choice of animal models used to evaluate retroviral-vector-based therapies.
0022-538X/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
The Resistance of Retroviral Vectors Produced from
Human Cells to Serum Inactivation In Vivo and In Vitro Is Primate
Species Dependent
*
Corresponding author. Mailing address: Chiron
Technologies, Center for Gene Therapy, 11055 Roselle St., San Diego, CA
92121. Phone: (619) 452-1288. Fax: (619) 623-9975. E-mail:
nick_depolo{at}cc.chiron.com.
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