Antigenic properties of the V1/V2 domain of HIV-1 gp120

Project Details


The goals of this project are to define conserved epitopes in the V1/V2 domain of HIV-1 gp120 that mediate virus neutralization and enhancement, and to use this information to develop an HIV
vaccine based on modified V1/V2 miniproteins. The structures of the alternate
V1/V2 conformers will be determined by MALDI analysis of proteolytic fragments
of the purified isomers. A number of human sera have been identified that
contain antibodies that react with conserved V1/V2 epitopes, including some
that recognize alternate conformational forms of V1/V2. Also available are sera
from V1/V2 immunized macaques that possess either neutralizing or enhancing
activities for specific M-tropic HIV-1 isolates. These antibodies will be
fractionated by immunoaffinity chromatography and characterized for specificity
for V1/V2 conformers, crossreactivity against distantly related sequences and
for neutralizing (or enhancing) activities against various viruses. Novel
monoclonal antibodies (Mabs) directed against functional targets in the V1/V2
domains will be isolated from hybridomas prepared from mice immunized with
various antigens, including V1/V2 miniproteins, recombinant gp120/140
molecules, and mouse cells expressing native HIV-1 Env proteins. These studies
will also utilize transgenic XenoMouse strains developed at Abgenix that
produce human immunoglobulins, in order to isolate human Mabs; because of the
human nature of these antibodies, any Mabs with potent neutralizing activities
that are isolated in these experiments could have direct utility as passive
immunotherapeutic agents in humans. Hybridomas will be generated by standard
technologies, and screened against the relevant immunogens. These Mabs will be
used to map epitopes that mediate viral neutralization and enhancement.
Finally, a panel of mutant V1/V2 miniproteins, based on both the CaseA2 and
SF162 sequences, will be prepared; mutations to be studied will include
N-linked glysosylation sites, deletions and alanine substitutions. The
immunoreactivities of the mutant proteins will be measured with available Mabs
and fractionated human and macaque sera, and the distribution of neutralization
and enhancement epitopes on the mutant proteins determined by absorption of
human and macaque antibodies that possess such activities. Selected mutant
proteins which preferentially express neutralization epitopes will be used to
immunize rats, and the neutralizing and/or enhancing activities of the
resulting sera quantitated. Modified V1/V2 miniproteins that induce effective
neutralizing responses against clinically relevant HIV isolates would provide
the basis of a V1/V2-based vaccine against HIV-1.
Effective start/end date8/3/057/31/06


  • Immunology


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