Programme Supplement [International Conference on AIDS (16th: 2006: Toronto, Canada)]

Late Breaker Abstracts

growth. Since efficient vaccines are not to be seen in the near
future, the prospects for a full-scale therapy seem poor. Our goal
is to develop a drug delivery system that would be able to target
specifically HIV reservoir cells. The system will deploy a variety
of none specific chemotherapeutic agents, that best fit toxicity
and adherence demands. Such a system harbors the potential to
destroy infected cells, thus depriving the virus' main resource
and halting the'disease without promoting the evolution of drugresistant strains. Proteo-liposomes might even undergo fusion
with roaming viruses.
Methods: We have constructed a proteo-liposomal system composed
of a magnetic bead surrounded by a lipid bi-layer containing pure,
oriented and biologically active CCR5. The CCR5 molecules are
anchored to the beads and are held in the correct orientation via
binding to 1D4-Mab attached to the beads. A model engineered BHK
cell-line transfected with HIV-1p89.6ENV was constructed for the
studies of proteo-liposomes interactions with gp120.
Results: SDS-PAGE and immuno-blotting has demonstrated that
the proteo-liposomes' protein composition was of 1D4 antibodies
and CCR5. Cryo-TEM imaging and confocal microscopy have
demonstrated a correct spatial distribution of the lipid bi-layers
around the beads. Binding of the proteo-liposomes to BHK cells
expressing HIV-1p89.6ENV was demonstrated using light and
confocal microscopy. To confirm the bio-activity of BHK/HIV1p89.6ENV the cells were co-cultured with Jurkat/CXCR4+/CD4+.
The viability of the Jurkat/CXC4+/CD4+ was reduced by 30%
following 24 hr co-culture incubation. Light microscopy cytometry
and FACS analysis have demonstrated that proteo-liposomes'
binding to BHK/HIV-1p89.6ENV cells was 3 fold higher then the
binding to BHK control cells.
Conclusions: The results imply that a drug delivery system based
upon CCR5 conjugated proteo-liposomes is feasible and may serve
as a potential ART strategy.
THLBO305
Drug candidate TATOOO2, a telomerase activator, enhances
antiviral functions of HIV-1-specific CD8 T cells
C.B. Harley', S.R. Fauce2, A.C. Chin', B.D. Jamieson2, O.O. Yang2,
R.B. Effros2. 1Geron Corporation, Menlo Park, United States,
2Geffen School of Medicine at UCLA, Los Angeles, United States
Background: New targets and therapeutic approaches for HIV1 infection are needed. Telomerase activation has been shown
to mitigate loss of replicative capacity and functional decline
caused by chronic stress and cellular aging. CD8+ T-cells play
a key immunoprotective role and we previously showed that
telomere-dependent senescence of these cells contributes to their
dysfunction. We discovered a small molecule telomerase activator,
TAT0002, and are developing it for HIV/AIDS therapy. TAT0002
significantly enhances proliferation, IFN-y production and HIV1-specific cytolytic activity of CD8 cells from infected donors.
Here we report recent progress on development of TAT0002 as
a therapeutic agent, including mechanistic studies and pilot
pharmacokinetic measurements.
Methods: The effects of 1 pM TAT0002 during a 14d expansion
of CD8+ T-cells from HIV-1-infected persons on 48h CD3 -stimulated production of MIP-la/p and RANTES was assessed by
ELISA. Dependence of TAT0002 effects on telomerase activation
was verified by co-incubation with a telomerase inhibitor.
Pharmacokinetics of orally administered TAT0002 in mice was
assessed with a newly developed LC/MS assay.
Results: The mean TAT0002-mediated enhancements of MIP-la,
MIP-ib, and RANTES production by CD8+ T-cells from 3 HIV-1 -infected donors were 24% (p<0.01), 33% (p<0.05), and 36% (p<0.01)
respectively. This TAT0002-effect was essentially eliminated by
co-incubation with a telomerase inhibitor, suggesting telomerasedependence and agreeing with prior results on TAT0002-mediated
enhancement of CD8+ T-cell antiviral activity. TAT0002 activated
telomerase in multiple cell systems at 10-1000 nM. Pilot oral PK
measurements of TAT0002 in mice showed reasonably sustained
levels in this range at the lowest dose tested (10 mg/kg; Cmax = 3
pM; apparent T(1/2)c-40min), suggesting that active doses should

be obtainable with oral formulation.

Conclusions: Mechanistic, safety, and PK data obtained to date suggest that
TAT0002 and telomerase represent a promising drug candidate and target for
treatment of HIV/-1-infected persons.
THLBO306
The HIV-1 envelope gene determines viral fitness in both
drug sensitive and resistant isolates
I. Nankya', A. Abraha', E. Fraundorf', A. Marozsan', Y. Gao', B.
Johnston', D. Katzenstein2, E. Arts'. 'Case Western Reserve
University, (1) Division of Infectious Diseases, School of Medicine,
Cleveland, United States, 2Stanford University, (2) Division of
Infectious Diseases and Geographical Medicine, Stanford, United
States
Background: HIV-1 subtype C is the most predominant the
global epidemic. Unlike other group M subtypes, subtype C is
predominantly CCR5 (R5); the CXCR4 (X4) phenotype is rare even
in late disease. We have demonstrated that like the subtype C
NSI/R5, the subtype C SI/R5 HIV-1 isolates are less fit than other
group M isolates. In addition, we showed that the efficiency of
host cell entry controls fitness andckthis has been mapped to the
envelope gene.
Methods:: Eight SI/X4 isolates were propagated by PBMC cocultivation, then used in pair-wise competition experiments with
SI/X4 isolates of subtypes A, B, C, D, CRF01 (E), and group O.
Coincidentally, half of these isolates harbored drug resistant
mutations; so we determined the role of the envelope gene in
controlling fitness in the presence of RT-Protease mutations. The
RT-Protease from each of these isolates was cloned into pNL4 -3 and was used to determine fitness. In addition, the env gene
from a drug resistant and a drug sensitive isolate were cloned
into pNL4-3. These env chimeric viruses were used in pair-wise
competitions with the other subtype-C SI isolates, SI/X4 reference
isolates, pNL4-3, and drug resistant reference isolates in both
PBMCs and MT-2 cells.
Results: In all competitions against other SI/X4, subtype C SI/
X4 isolates were significantly less fit. Using the RT-Protease, the
drug resistant isolates had low fitness while the sensitive isolates
had high fitness. Using the envelope to determine fitness, the
chimeric viruses exhibited fitness values that were comparable to
their parental isolates. Surprisingly, the drug resistant isolate that
exhibited low RT-Protease fitness, had a high total relative fitness
value when both the whole virus and env chimera were used in
competitions.
Conclusions: These findings further confirm that even in the
presence of drug resistant mutations, the envelope gene plays a
major role in fitness.
THLBO307
A bioinformatic approach to study escape mutations of HIV1: analysis of gag genes
H. Peters', M. Mendoza', R. Capina', M. Luo2, X. Mao1, M.J.
Gubbins', I. MacArthur', B.B. Sheardown', J. Kimani3, J.
Ndinya-Achola3, S. Njenga3, J.B. Bwayo3, S. Thavaneswaran',
F.A. Plummer'. 'Public Health Agency of Canada, National
Microbiology Laboratory, Winnipeg, Canada, 2University of
Manitoba, Medical Microbiology, Winnipeg, Canada, University
of Nairobi, Department of Medical Microbiology, Nairobi, Kenya
Background: Through mutations, HIV-1 can rapidly adapt
to the selective pressure by the host immune system. Some
mutations allow viral escape at a cost of fitness, while others
can increase the pathogenicity of the virus. Our study is to use
a bioinformatic approach to identify and classify CTL escape
mutations.
Methods: Proviral DNA was isolated from HIV positive women
of Pumwani Sex Worker cohort from Nairobi, Kenya, and the
gag gene was amplified and sequenced. Phylogenetic analysis
was conducted to classify viral subtypes (MEGA 3.1). QUASI
analysis was conducted to identify positive selected amino acids
residues. SPSS 11.0 was used to correlate positive selected

sites with patient HLA class I and CD4 counts.

Late Breaker
Abstracts

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XVI INTERNATIONAL AIDS CONFERENCE * 13-18 AUGUST 2006 * TORONTO CANADA * PROGRAMME SUPPLEMENT