Oral Abstract Session 01 - Global HIV Vaccine Enterprise

ORAL ABSTRACT SESSIONS
72
Oral Abstract Sessions
Oral Abstract Session 07: B Cell Responses
OA07.03
Deep Sequencing with Longitudinal Sampling of
a VRC01-Like-Antibody Response in a Chronically
Infected Individual
Z. Zhang 1 , X. Wu 2 , N. Longo 2 , B. Zhang 2 , J. Zhu 2 , C. Nisc 3 ,
J.C. Mullikin 3 , L. Wu 2 , G.J. Nabel 2 , M. Connors 4 , P.D. Kwong 2 ,
J.R. Mascola 2 , L. Shapiro 1
1 Columbia University, New York, NY, USA; 2 Vaccine Research
Center, NIAID, NIH, Bethesda, MD, USA; 3 National Human
Genome Research Institute, Bethesda, MD, USA; 4 National
Institute of Allergy and Infectious Diseases, NIH, Bethesda,
MD, USA
Background: VRC01-like antibodies use heavy chain mimicry of
the CD4-receptor to achieve effective neutralization of HIV-1. The
VRC01-like antibodies that have been observed in a number of
HIV-1-infected individuals (i) display extensive somatic changes
(70-100 nucleotide changes in VH-gene), (ii) can be detected only
after several years of infection, (iii) derive from VH1-2, and (iv)
are compatible with several different heavy J chains and different
light chains.
Methods: To understand the persistence, evolution, and lineage
of VRC01-like antibodies, we sampled PBMCs from donor 45,
the source of VRC01 and VRC03 antibodies, at approximately
yearly intervals over a 15-year period, and performed deep
sequencing on the heavy and light chain variable portions of
expressed antibodies. Anti-idiotypic antibodies were used to
correlate mRNA levels of antibodies identified by the deep
sequencing with expressed levels of these antibodies in serum.
Results: High expression levels of VRC01-like antibody
sequences persisted over the entire 15-year period. Multiple
lineages of VRC01-like antibodies were detected at each
time point, and some of these, in particular the lineages
that include VRC01 and VRC03, persisted over multiple time
points, and displayed extensive branching in their evolution.
Conclusion: Deep sequencing provides a means to define the
genetic record of the lineage and maturation of antibodies
effective at neutralizing HIV-1. Precise definition of the natural
ontogeny of broadly neutralizing antibodies may be essential
in defining appropriate strategies to elicit such antibodies in
vaccine settings.
AIDS Vaccine 2012
OA07.04
Antibody Effector Function Is Regulated by a
Combination of Adaptive and Innate Signals
A. Mahan 1 , K. Dionne 2 , J. Eusebio 2 , G. Alter 2
1 Harvard University, Charlestown, MA, USA; 2 Ragon Institute,
Charlestown, MA, USA
Background: The Fc region of IgG contains a single N-glycosylation
site, which is known to be important for effecting immune
activation through interaction with Fc receptors and complement
molecules. Changes to the structure of these sugars can thus be
very influential in determining the specific effector function of
individual antibodies. Whereas therapeutic antibodies can be
produced with particular effector functions in vitro, little is known
regarding how glycosylation is regulated in primary B cells.
Methods: Purified B cells were stimulated with a variety of
synthetic TLR ligands alone or in combination with soluble CD40L,
anti-IgG, anti-IgM, or supernatants derived from stimulated
antigen presenting cells. After 16 hours, quantitative RT-PCR was
used to determine expression of genes known to be specifically
involved in IgG N-glycan synthesis.
Results: We found that the expression of glycosylation genes
is significantly impacted both by specific TLR stimulation alone
and in combination with adaptive signals received either
through the B cell receptor or CD40. Specifically, virus-derived
stimuli that activate TLR 7, 8 or 9 can significantly decrease
the expression of galactose adding enzymes, whereas TLR 9
stimulation in combination with CD40 stimulation decreases
the expression of both sialic acid– or GlcNac-adding enzymes.
These changes in expression result in the production of
antibodies with Fc glycan structures with increased NK cell–
and monocyte-recruiting capabilities.
Conclusion: Overall, these results are the first to show that the
production of antibodies with specific effector functions can be
regulated by external stimuli, including both innate and adaptive
immune signals, suggesting that antibodies with specific, strong
effector functions can be induced in vivo following vaccination.