CCR5 Ligand Levels and Immune Response to HIV Vaccines [Revised Proposal]

ZRG1 VACC (01) 2 1 RO1 A1052038-01A1
GARZINO-DEMO, A
1R1Al052038-01Al GARZIN O-DEMO, A.
RESUME AND SUMMARY OF DISCUSSION: The amended application proposes to develop,
standardize and apply methods for the rigorous analyses of CCR5 ligand release from antigen
stimulated cells that will be suitable for screening recipients of candidate HIV vaccines.
The development of laboratory correlates of vaccine immunity is highly critical for selection of effective
vaccine strategies. Thus, the application is addressing an important question in evaluating the role of
chemokines in vaccine-induced immunity. The New Investigator PI, Dr. Garzino-Demo, has significant
experience in studies of chemokines, is highly qualified to carry out the proposed studies, and is in an
excellent environment. However, there is little innovation in the application, as the investigators will
simply develop ELISA assays to quantitate in vitro antigen induced responses. It is also proposed to
develop RNA based assays to quantify the chemokines, but no preliminary data are provided that RNA
detection might be a relevant marker for monitoring vaccine responses. A more significant approach
would be to develop novel technology to allow for direct detection of chemokines from blood samples of
vaccinated subjects. There will be limitations as well in that only frozen cells from vaccinees may be
available, at least for the initial studies. Overall, it is not clear that the results of these proposed studies.would add significantly to our understanding ofrponses to vaccine or predictabjtof immune status
Sover current assays..DESCRIPTION (provided by applicant): The only known correlate of resistance to HIV infection is the
absence of CCR5, which is the major host determinant for primary infection. Any immune response
capable of down regulating CCR5, or otherwise influencing its capacity to act as an HIV coreceptor,
warrants serious analyses in the context of HIV vaccine development. RANTES, macrophage
inflammatory protein (MIP)-la and MIP-1B which are released during innate and cognate immune
responses, potently inhibit HIV by binding to CCR5 coreceptor. Accordirigy, our studies, alorg-with
those of other groups, show that the release of these inhibitors is associated with natural resistance to
HIV infection in high-risk individuals. Similarly, the increased production of the same chemokines is
correlated with protection from SIV or SHIV infection in vaccinated primates. These observations
support our hypothesis that HIV vaccines can prime the immune system to release CCR5 ligands in
response to cognate viral antigen, thus providing a correlate of immunity to HIV infection. Our
preliminary data showing readily detectable increases in CCR5 ligands in PBMC cultures stimulated
with vaccine antigen indicates this possibility can be explored using ELISA-based detection methods.
Therefore, studies to determine changes in antigen induced chemokine release in vaccines are clearly
warranted. In this project, we will develop, standardize and apply methods for the rigorous analyses of
CCR5 ligand release from antigen stimulated cells that will be suitable for screening vaccinees. These
analyses will, for the first time, incorporate the means to specifically quantify LD78Beta and the natural2 isoform of RANTES, both of which have been associated with the most potent antiviral effects in vitro.
The application of the assay system will provide a complete and detailed profile of chemokine release
that is directly relevant to vaccine development and testing. Furthermore, the system will ultimately
permit an evaluation of whether HIV suppressive chemokine release plays a role in providing protection
against HIV infection.
CRITIQUE 1:
SIGNIFICANCE: Chemokines clearly have been shown to be a critical component in modulating HIV
infection given their ability to block HIV entry. This application proposes to extend our knowledge of
chemokines by refining assays for in vitro detection of chemokine and developing additional assays to
measure important functional chemokine LD78 and -2 isoforms of RANTES. The results of such
studies; however, will be of a limited impact as simply developing two more chemokine ELISAs will not
provide major advancement of the field. The application of ELISA assay is not highly original. A more
significant approach would be to develop novel technology to allow for direct detection of chemokines
from blood samples of vaccinated subjects. In addition the investigators will not be able to achieve their

ultimate goal of demonstrating that chemokines are important correlates of immunity as no phase Ill