CCR5 Ligands in HIV Vaccines

Studies to be performed:

This study is a logical extension of our demonstration that the CCR5 ligands,
RANTES, MIP-lc and MIP-1J3, are major HIV suppressor factors. Since these molecules
represent soluble antiviral factors released during immune responses, it was reasonable
for us to immediately propose chemokine release as a potentially important mechanism
for the control of HIV infection. Stated simply, higher HIV-suppressive chemokine
production should limit coreceptor availability and inhibit the spread of HIV infection.
A truly relevant evaluation of this possibility can only come from the studies of
clinical samples. So far, our cross-sectional studies have supported our hypothesis by
establishing an association between higher levels of some CCR5 ligands and
asymptomatic status in HIV infection. A number of independent studies are entirely
consistent with our findings. However, any firm conclusions regarding an association
between chemokine release and protection from HIV infection requires a longitudinal
study that can equate response to activation with a relevant antigen and outcome of
infection. Since the role of chemokines in HIV infection is an important and unresolved
issue, such a study is entirely warranted at this time.
The study will be carried out by analyzing chemokine protein release from
freshly collected, activated PBMC (see below for details). Commercial ELISA will be
used for measuring the expression of chemokines throughout the project, with the
exception of -2 RANTES (for the detection of which we have developed and elisa assay
at IHV) and LD78f3since ELISA for this molecule is currently unavailable (although we
plan to develop an ELISA for this molecule, similarly to that detecting -2 RANTES). In
the latter case molecular techniques will be employed.
Sample Collection
The studies in this program will be carried out with primary cells obtained from
freshly collected blood.
All of the samples will be collected anonymously, and coded with numbers
(subject ID and visit number) assigned at the site of collection. The collection site will
collect and store clinical data of the subjects in a database. Samples will be drawn as
specified in the approved protocol. Fresh PBMC will be obtained by centrifugation in
CPT tubes (Becton Dickinson) of whole blood from vaccinated and control subjects. 25
106 PBMCs, and 2-3 ml of plasma from each subject will then be transferred to IHV
for chemokine assays. All of the chemokine assays to be performed for this study will be
performed blindly at TIV Every six months, IHV will forward chemokine assays data to
the collection site, which will match the clinical data with chemokine assays data, based
on ID and visit numbers. CD4+ and CD8+ lymphocyte counts will be determined and HIV
status will be monitored by the HVTN central laboratory. All data will be collected in
Excel database format. Statistical analysis of the data will be performed primarily at IIHV.
All of these procedures have been already efficiently performed for our published crosssectional study of HIV-positive subjects.

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