European Journal of Medical Research - Deutsche AIDS ...

128 EUROPEAN JOURNAL OF MEDICAL RESEARCH
June 27, 2007
Objective: To evaluate the safety and immunogenicity of
tgAAC09 in healthy, HIV-uninfected adult volunteers at low
risk for HIV infection.
Methods: In this dose-escalation study, 80 healthy, HIV-uninfected
volunteers received a single intra-muscular injection
of tgAAC09 at different doses: 3x109 DRP (n=16), 3x1010
DRP (n=23), 3x1011 DRP (n=25) or placebo (n=16). In addition,
21 of 50 volunteers received a boost vaccination of
tgAAC09 at a dose of 3x1011 DRP or placebo. T-cell responses
were assessed by IFN- ELISPOT assay, anti-AAV2
neutralizing titers (NT) by a cell-based assay, and vaccine
shedding by PCR.
Results: The vaccine was well-tolerated after both initial and
boost vaccination. Mild-to-moderate local and systemic reactogenicity
was experienced by app. 15-20% of volunteers. No
vaccine-related SAE`s were reported. The proportion of reactogenicity
and AE`s were evenly distributed among the different
dose groups and placebo. There was no evidence of vaccine
shedding. At baseline, 48% of European and 97% of Indian
volunteers had detectable NT against AAV2. The proportion
of volunteers with four-fold or greater rise in anti-
AAV2 NT increased with higher doses and after boost vaccination.
HIV-specific T-cell responses were detected in 9/64
vaccinees, with 24% (6/25) of volunteers in the highest dose
group responding. All responses were to gag epitopes and the
magnitude was moderate (38-385 SFC/106 PBMC). No induction
of antibody to HIV was observed.
Conclusions: Vaccination with tgAAC09 appears to be safe
and well-tolerated. Immunogenicity data indicated a moderate
response at the highest dose, directed to gag. Future clinical
trials will focus on higher doses of tgAAC09, the optimal interval
for boost vaccination, the effect of pre-existing immunity
to AAV2, and evaluating prime-boost regimens.
F.23 (Poster)
Induction of neutralising antibodies after
immunisation with the transmembrane envelope
proteins p15E of gammaretroviruses: Implication
for the development of an HIV vaccine
Fiebig U. 1 , Langhammer S. 1 , Behrendt R. 1 , Kurth R. 1 ,
Denner J. 1
1 Robert Koch-Institut, Berlin, Germany
Objective: Neutralising antibodies specific for the membrane-proximal
external region (MPER) of the transmembrane
envelope (TM) protein gp41 of HIV such as 2F5 and
4E10 have been isolated from infected patients. These antibodies
are broadly neutralising and decreased the HIV load in
clinical trials. However, many attempts to induce such antibodies
failed so far.
To study the mechanism of induction and the efficacy of
neutralising antibodies directed against the retroviral TM proteins,
the TM proteins p15E of three different gammaretroviruses
(porcine endogenous retrovirus, PERV; feline
leukaemia virus, FeLV, and Koala retrovirus, KoRV) were
used in immunisation experiments.
Methods: Recombinant p15E were produced; rats, goats and
cats were immunised, neutralising antibodies were analysed
in a real-time PCR based infection assay; ELISAs, Western
blots and epitope mappings were performed, cats immunised
with FeLVp15E were challenged with infectious FeLV.
Results: Antibodies neutralising PERV, FeLV and KoRV
were obtained after immunisation with the corresponding
p15E. Two epitopes, one located in the N-terminal part near
the fusion peptide (designated E1), the other in the C-terminal
MPER (E2) of p15E were found in all cases. The localisation
of E2 corresponds to the localisation of the epitopes of
2F5/4E10 and despite the evolutionary difference of HIV and
gammaretroviruses a limited sequence homology was observed.
Neutralising antibodies specific for p15E of FeLV
prevented in immunised cats an antigenemia, demonstrating
their efficacy in vivo.
Conclusion: These data show that the E2 domain represents a
highly vulnerable target for neutralisation of retroviruses.
Since by us (WO 2005/021574) and others a E1 domain was
identified in gp41 of HIV, immunisation with proteins containing
these domains may induce broadly neutralising antibodies
of the type 2F5 and 4E10.
F.24 (Poster)
A novel gene therapeutic strategy against HIV-1
infection using the suicide protein tBid
Hülsmann P.M. 1 , Hofmann A.D. 1 , Rauch P. 1 , Wolff H. 2 ,
Berens C. 3 , Metzner K. 1
1 University of Erlangen-Nuremberg, Institute of Clinical and
Molecular Virology, Erlangen, Germany, 2GSF-Helmholtz
Research Center for Environment and Health, Institute of
Molecular Virology, Neuherberg, Germany, 3 University of
Erlangen-Nuremberg, Chair of Microbiology, Microbiology,
Erlangen, Germany
Objective: Specific elimination of human immunodeficiency
virus type 1 (HIV-1) infected cells by HIV-1 LTR driven suicide
genes presents a promising strategy in gene therapy of
HIV-1. Clinical applications of this approach depend on a fast
and effective suicide gene which is exclusively expressed in
HIV-1 infected cells. These preconditions have not yet been
fulfilled and, thus far, success of suicide approaches is limited.
It was recently shown that expression of truncated Bid
(tBid), a human pro-apoptotic protein, rapidly and efficiently
induces apoptosis. Thus, we tested tBid in the context of a
novel HIV-1 LTR-based, Tat- and Rev-dependent transgene
expression vector as a new potential suicide strategy in the
gene therapy of HIV-1.
Methods: tBid was cloned into the HIV-1 LTR-based Tatand
Rev-dependent expression vector pLRed2xINSR replacing
dsRed. The effects of tBid were then analyzed in the presence
or absence of the HIV-1 proteins Tat and/or Rev in transiently
and stably transfected 293T and HeLa cells. Cell death
was determined 24 hours after transfection by PI-staining.
The original vector pLRed2xINSR was used as control and
dsRed expression determined by FACS and fluorescence-microscopy.
Results: tBid, expressed by the strong constitutive CMV promoter,
was highly efficient in inducing apoptosis in both
293T and HeLa cells in less than 24 hours showing that tBid
is effective in these cell lines. When expression of tBid was
driven by the HIV-1 LTR promoter, induction of apoptosis
was not observed in both cell lines in the absence of co-factors
showing that this system is not leaky. Coexpression of
Rev alone did not lead to induction of apoptosis, but coexpression
of Tat alone moderately induced apoptosis. This effect
was strongly enhanced by the co-expression of Tat and
Rev. Cell death was rapidly observed within 24 hours. Equivalent
results for dsRed expression/fluorescence were obtained
using the control vector pLRed2xINSR.