Oral Abstract Session 01 - Global HIV Vaccine Enterprise

POSTERS
Posters
Topic 12: Vaccine Concepts and Design
P12.67 LB
Simple, Scalable And Robust Purification Of Two HIV-
1 Subtype C gp120 Monomer Subunit Antigens For
Phase II Clinical Trial In Republic Of South Africa
Y. Wen 1 , S. Stephenson 1 , C. Zambonelli 1 , S. Hilt 1 , M. Wininger 1 ,
A. Dey 1 , S. Barnett 1 , A. Carfi 1
1 Novartis, Cambridge, MA, USA
Background: Development of an effective vaccine against HIV-
1 is challenging due to various viral evolutionary mechanisms
to evade human immune system. The partial efficacy of the
recent RV144 vaccine efficacy trial in Thailand provides hope for
improvements of vaccine regimens for higher efficacy. A Phase
IIb proof-of-concept clinical trial in the Republic of South Africa
(RSA) is planned to confirm and extend the results of the RV144
trial with the vaccine strategy of poxvirus vector prime plus
envelope protein boost.
Methods: We selected two HIV subtype C gp120 vaccine
antigens, TV1.C gp120 and 1086.C gp120, formulated with
Novartis proprietary adjuvant, MF59 as protein boosts of the
clinical trial.
Results: To produce TV1.C gp120 and 1086.C gp120 monomers,
we generated CHO stable cell lines for both gp120, which
consistently expressed gp120 subunits with high yield. Simple,
scalable and robust antigen purification processes were
developed to generate both gp120 proteins. The ion-exchange
based purification strategy enabled the separation of gp120
monomer from dimer and produced gp120 monomer with high
purity and homogeneity.
Conclusion: Purified gp120 monomers were stable, either
alone or in combination, and when formulated with adjuvant
MF59. Finally, the early evaluations showed that both
gp120 monomers were immunogenic and able to elicit high
neutralizing antibody titer.
274
AIDS Vaccine 2012
P12.68 LB
2G12/PGT-Binding Yeast Glycoprotein Gp38
Elicits Mannose-Specific HIV-1 Env Cross-Reactive
Antibodies
H. Zhang 1 , H. Fu 1 , B. Liu 1 , R.J. Luallen 1 , R.W. Doms 2 , D.F. Smith 3 ,
Y. Geng 1
1 ProSci Inc., Poway, CA, USA; 2 University of Pennsylvania,
Philadelphia, PA, USA; 3 Emory University, Atlanta, GA, USA
Background: The increasing numbers of broad neutralizing
antibodies (bNAbs) that target carbohydrates of HIV envelops
highlight the importance of designing immunogens to elicit such
types of bNAbs for an effective HIV vaccine.
Methods: PGT bNAbs-cross reactive proteins were detected by
Western blots and identified by nano-LC-MS/MS. Rabbit antisera
were raised with single PGT bNAbs-reactive yeast glycoprotein,
and tested by ELISA, Western blots and glycan microarray. HIV-1
pseudoviruses were generated in 293T cells, and neutralization
assay was performed using TZM-bl cells.
Results: Using the newly identified, glycan-specific PGT bNAbs
to search for their binders from a triple mutant(TM) strain of
Saccharomyces cerevisiae, we found that the PGT bNAbs not only
bind to the previously identified 2G12-reactive glycoproteins but
also recognize several unknown proteins in TM yeast. One of
them was identified as a short version of Gp38 with N-terminus
truncation. Based on immunization of rabbits with various
formulations and strategies, we found that a high titer of HIV-1 Env
cross-reactive antibodies was induced when using a promiscuous
T-cell epitope peptide conjugated Gp38 in a formulation with a
Toll-like receptor 2 agonist and aluminum salts. The Gp38-elicited
antibodies could bind to a broad range of monomeric gp120s
from HIV and SIV. Moreover, the antibodies could also efficiently
neutralize HIV-1 pseudoviruses when the viruses were produced
in the presence of a mannosidase inhibitor kifunensine, which
enriches high-mannose Man9GlcNAc2 N-linked glycans. Glycan
microarray analysis showed that these antibodies bind to the
synthetic Manα1,2-Manα1,2-Man containing oligosaccharides
Conclusion: These data suggest that yeast glycoprotein Gp38, as
well as its truncated form, is an efficient binder to the glycanspecific
HIV bNAbs, and that Gp38 is able to induce a strong glycanspecific
HIV-reactive antibody response when incorporated with
appropriate adjuvants. These results encourage us to further
explore the strategies to induce 2G12/PGT-like antibodies using
Gp38 as well as its truncated form.