Oral Abstract Session 01 - Global HIV Vaccine Enterprise

POSTERS
Posters
Topic 8: Mucosal Immunity
P08.17
Biodistribution of Neutralizing Monoclonal
Antibodies IgG1 b12 and LALA in Mucosal and
Lymphatic Tissues of Rhesus Macaques
A.J. Hessell 1 , E. Epson 1 , B. Moldt 2 , E. Rakasz 3 , S. Pandey 1 ,
W.F. Sutton 1 , Z. Brower 1 , V.M. Hirsch 4 , D.R. Burton 5 ,
N.L. Haigwood 1
1 Oregon Health & Science University, Oregon National Primate
Res Ctr, Beaverton, OR, USA; 2 The Scripps Research Institute,
La Jolla, CA, USA; 3 University of Wisconsin-Madison, Madison,
WI, USA; 4 NIAID, NIH, Bethesda, MD, USA; 5 The Scripps
Research Institute and IAVI Neutralizing Antibody Center, La
Jolla, CA, USA
Background: HIV-1 transmission occurs predominantly through
mucosal surfaces. In macaque models of SHIV mucosal
transmission, passive administration of the monoclonal
neutralizing antibody IgG1 b12 (b12) can protect against virus
infection. However, an Fc variant of b12, deficient in FcγR and
complement binding, (LALA) had diminished protective capacity.
Concentrations and kinetics of b12 and LALA in serum and in
mucosal secretions were determined in the protection studies,
but the biodistribution and kinetics of the antibodies in mucosal
and lymphatic tissues and around the site of viral challenge have
not been assessed.
Methods: We conducted a pilot study to develop protocols to
process macaque tissue specimens and to detect and quantify
passively transferred neutralizing antibodies (NAbs) in tissue
homogenates. To confirm that transport of LALA to the site
of challenge was not altered from that of b12, we obtained
secretions and tissue specimens from rhesus macaques that had
been passively infused with either b12 or LALA at 24 hours prior to
necropsy, matching the time of challenge in the protection study.
Results: We quantified passively administered b12 and LALA in a
variety of macaque mucosal and lymphoid tissues and assessed
the neutralization capacity of the NAbs localized in vaginal and
rectal sites typically exposed to virus in challenge studies. We
demonstrated that the rapid distribution and broad delivery to
lymphoid and mucosal tissues of both b12 and LALA are equivalent.
Conclusion: We developed and utilized a methodology
to evaluate the transudation of transferred antibody into
mucosal and lymphatic tissues and showed that the reduction
in the protective capacity of LALA compared to b12 cannot
be attributed to a differential effect of biodistribution. This
methodology will be useful to describe the pharmacokinetics
of newly discovered MAbs and may inform about the
characteristics of therapeutic antibodies or antibodies to elicit
by vaccination.
198
AIDS Vaccine 2012
P08.18 LB
T cell Immune Quiescence As A Contributor To
Resistance To Infection Among HIV Exposed
Seronegative (HESN) Commercial Sex Workers from
Nairobi, Kenya
K.R. Fowke 1 , T.B. Ball 2 , J. Kimani 3 , F.A. Plummer 1
1 University of Manitoba, Winnipeg, Canada; 2 Public Health
Agency of Canada, Winnipeg, Canada; 3 Kenyan AIDS Control
Program, Nairobi, Kenya
Background: Participants from the Majengo Commerical Sex
Worker Cohort in Nairobi, Kenya have been intensely exposed
to HIV for 7-20 years of follow-up, and yet have remained
uninfected. Since activated CD4+ T cells are much more
susceptible to HIV infection and have been suggested to form the
initial focus of mucosal infection, we have conducted a number
of studies to characterize the T cell phenotype in the mucosal
and systemic compartments of these HIV exposed seronegative
women (HESN).
Methods: Representative sampling (n=~30) of HESN women
and a similar sized control group of newly enrolled commercial
sex workers were compared. Gene expression analysis, immune
phenotyping, and in vitro HIV infection assays were performed
on peripheral blood mononuclear cells. Mucosal assessment of
the female genital tract (FGT) included proteomic analysis by
mass spectrometry, flow cytometry and cytokine/chemokines
determinations by bead arrays.
Results: Gene expression analysis revealed the HESN women
showed reduced gene levels for pathways involved in T cell
receptor activation and HIV host dependent factors. Systemic
CD4+ T cells showed lower levels of immune activation (CD69) and
higher levels of regulatory T cells (T regs). Infection frequency, the
number of infected replicate wells, was lower in the HESN women
and correlated with ex vivo assessment of reduced T cell activation
and elevated T reg levels. Mucosal assessment by proteomics
showed higher levels of anti-inflammatory serine proteases and
lower levels of the chemokines IP-10 and MIG, which functions are
to recruit activated T cells into the mucosal environment.
Conclusion: Together, these data suggest that the HESN women of
the Majengo Cohort display a T cell Immune Quiescent phenotype
that is characterized by fewer activated T cells, more regulatory T
cells and a mucosal environment that favours quiescent cells. The
result is an environment that is not favorable for the establishment
of HIV infection.