REVIEW ARTICLE
Lentiviral vectors: excellent tools for experimental
gene transfer and promising candidates for gene
therapy
Elisa Vigna
Luigi Naldini*
Laboratory for Gene Transfer and
Therapy, IRCC, Institute for Cancer
Research and Treatment, University
of Torino Medical School, Candiolo
(Torino), Italy
*Correspondence to: Luigi Naldini,
Laboratory for Gene Transfer and
Therapy, IRCC, Institute for Cancer
Research and Treatment, University
of Torino Medical School,
Strade Prov. 142, Km 3.9,
1060 Candiolo (Torino), Italy
E-mail: lnaldini@ircc.unito.it
Received: 24 May 2000
Revised: 23 June 2000
Accepted: 30 June 2000
Summary
Lentiviral vectors are tools for gene transfer derived from lentiviruses. From
their ®rst application to now they have been strongly developed in design, in
biosafety and in their ability of transgene expression into target cells. Primate
and non-primate derived lentiviral vectors are now available and with both
types of systems a lot of studies tuned to improve their performances in a
large number of tissues are ongoing. Here we review the state of the art of
lentiviral vector systems discussing their potential for gene therapy. Copyright
# 2000 John Wiley & Sons, Ltd.
Keywords gene transfer; gene therapy; lentiviral vector; HIV-derived
vector; biosafety; non-primate lentiviral vectors
Introduction
Lentiviruses are a family of complex retroviruses inducing chronic and
progressive disease typically associated with infection of macrophages, a
terminally differentiated cell type. Gene transfer vectors were derived from
lentiviruses to complement the successful features of previously developed
retroviral vectors ± ef®cient integration in the chromatin, absence of viral
genes from the genetic information transferred to the recipient, and lack of
pre-existing immunity in the recipient ± with the ability to infect non-dividing
cells [1±3]. This simple concept has met with considerable success, and a
rapidly increasing number of laboratories have embarked on perfecting vector
systems based on lentiviruses and probing their gene transfer potential in a
variety of applications. Remarkable advances were made in vector design that
improved the biosafety and ef®ciency of gene transfer, and evidence for a
unique gene delivery capability was obtained in selected target tissues.
However, we still lack a detailed understanding of the biological bases, and
the actual limits, of the performance of lentiviral vectors in most target
tissues. Furthermore, validation of the therapeutic potential of this new
vector system in established preclinical models of disease is needed, and the
preferred route to translate it to the clinical arena is still highly debated.
Design of lentiviral vectors
The design of viral vectors is based on the separation of cis-acting sequences
required for the transfer of the viral genome to target cells from the trans-
acting sequences encoding the viral proteins [4,5]. Vector particles are
assembled by viral proteins expressed in trans from construct(s) devoid of
most viral cis-acting sequences (packaging constructs). The viral cis-acting
THE JOURNAL OF GENE MEDICINE
J Gene Med 2000; 2: 308±316.
Copyright # 2000 John Wiley & Sons, Ltd.