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J. Virol., May 1996, 3290-3297, Vol 70, No. 5
Y Wu, L Duan, M Zhu, B Hu, S Kubota, O Bagasra and RJ Pomerantz
Intracellular immunization to target the human immunodeficiency virus type
1 (HIV-1) regulatory protein Rev has been explored as a genetic therapy for
AIDS. Efficient intracellular expression of rearranged immunoglobulin heavy
and light chain variable regions of anti-Rev monoclonal antibodies, with
various vectors, and subsequent inhibition of HIV-1 replication have been
previously reported by our laboratories. To further understand the
molecular mechanisms and effects that intracellular anti-Rev single chain
variable fragments (SFvs) have against HIV-1, via blocking of Rev function,
two anti-Rev SFvs which specifically bind to differing epitopes of the Rev
protein have been cloned. One SFv binds to the Rev activation domain, and
the second SFv binds to the distal C terminus of Rev in the nonactivation
region. Further studies now demonstrate that both anti-Rev SFvs lead to
variable resistance to HIV-1 infection. Although binding affinity assays
demonstrated that the SFv which specifically recognizes the Rev activation
domain (D8) had an extracellular binding affinity significantly lower than
that of the SFv specific to the nonactivation region (D1O), the SFv D8
demonstrated more potent activity in inhibiting virus production in human
T-cell lines and peripheral blood mononuclear cells than did SFv D10. Thus,
extracellular binding affinities of an SFv for a target viral protein
cannot be used to directly predict its activity as an intracellular
immunization moiety. These data demonstrate potential approaches for
intracellular immunization against HIV-1 infection, by efficiently blocking
specific motifs of Rev to after the function of this retroviral regulatory
protein. These studies extend the understanding of the effects, on a
molecular level, of SFvs binding to critical epitopes of Rev and further
suggest that rational design of SFvs, with interactions involving specific
viral moieties which mediate HIV-1 expression, may hold promise for the
clinical application of genetic therapies to combat AIDS.
Copyright © 1996, American Society for Microbiology
Binding of intracellular anti-Rev single chain variable fragments to different epitopes of human immunodeficiency virus type 1 rev: variations in viral inhibition
Dorrance H. Hamilton Laboratories, Center for Human Retrovirology, Division of Infectious Diseases, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
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