Abstract Book Vol. 2 [International Conference on AIDS (14th: 2002: Barcelona, Spain)]

XIV International AIDS Conference

Abstracts ThPeA7115-ThPeA7118 363

ThPeA7115 Parasitic infection alters the quality of the immune
response to HIV-1 vaccines
J.D. Boyer, R. Nelson, T Robinson, P. Scott, D.B. Weiner. University of
Pennsylvania, Philadelphia, PA, United States
Background: More than 95% of all HIV-infected people now live in the Developing World, and 95% percent of all deaths have occurred among its people.
In these countries, chronic parasitic infection adds another level of complexity to
AIDS vaccine development. Helminthic and protozoan infections are common in
developing countries. Approximately 1.5 billion people carry a parasitic burden.
These persons are in a constant state of immune activation with a dominant Th2
type of cytokine profile, high IgE levels, and eosinophilia. Such an immune profile
may have an adverse impact on the efficacy of HIV-1 vaccines.
Methods: We studied the impact of parasitic infection on the vaccine induced
cellular immune response. Balb/c mice were infected with L. major. The immune
response was assessed by a ELISPOT.
Results: A Th2 immune profile was observed two weeks post parasitic infection.
Following the establishment of chronic parasitic infection the mice were immunized with a DNA HIV-1 vaccine. The level of vaccine induced CD8 and CD4
responses were assessed. We observed that the number of CD8 lymphocytes
able to secrete IFN-gamma following stimulation with HIV-1 antigen decreased
from approximately 200 to 20 lymphocytes. Yet, we observed a slight increase in
the number of HIV-1 antigen specific CD4 lymphocytes secreting INF-gamma in
the parasitically infected mice as compared to the uninfected, HIV-1 DNA vaccinated mice. Importantly, we have observed that the CD8 antigen specific cellular
response to HIV-1 DNA vaccines was significantly enhanced by the addition of
IL-15 independently of CD4 T cell expansion.
Conclusions: It may be benificial to enhance a vaccine induced cellular immune
response by co-injecting DNA plasmids that code for cytokines that enhance the
CD8 immune response. And, our data indicate that IL-15 could be particularly
valuable in developing countries where many individuals have a chronic parasitic
infection.
Presenting author: jean boyer, 422 curie blvd, 505 stellar-chance, philadelphia,
pennsylvania, United States, Tel.: [phone], Fax: [phone], E-mail:
[email protected]
ThPeA7116 IFN-y ELISPOT, intracellular cytokine staining
assays and Cr51-release CTL assay in HIV-1
subtype A/E infected Thais with CD4>300
cells/mm3: a comparison study
K. Ruxrungtham', S. Buranapraditkun', P. Hansasutal, S. Rowland-Jones2,
S. Sirivichayakul', M. Honda3, P. Warachit4, P. Phanuphak'. 'Division of Allergy
and Clinical Immunology, Faculty of Medicine, Chulalongkorn University
Bangkok, Thailand; 2John Radcliffe Hospital, Oxford, United Kingdom; 3National
Institute of Infectious Disease, Tokyo, Japan; 4Department of Medical Science,
Bangkok, Thailand
Background: IFN-y ELISPOT and intracellular cytokine staining (ICCS) assays
have recently been commonly used in subtype B and some non-B HIV-1 specific
CTL researches both in the pathogenesis and vaccine evaluation. However, these
assays need to be validated in countries with a high prevalence of subtype A/E
infection such as Thailand.
Method: HIV-lgag specific CTL responses were compared between IFNyELISPOT and Cr51-release assay, and between IFN-yELISPOT and ICCS assay in patients infected with subtype A/E. HIV-1 subtype A/E gag (vT142) and A
pol (vT143) recombinant vaccinias were provided by NIH AIDS Reagent Program,
USA. The positive cut-off of ELISPOT was 60 SFU/106 PBMCs and 2 folds higher
than the background. The positive cut-off of ICCS was >3 SD of HIV-seronegative
subjects that is >0.2% IFN-y+, CD69+, CD8+ cells.
Results: In the ELISPOT vs Cr51-release assay comparison, 25 HIV-1 -infected
Thai patients were evaluated. All showed CTL activity against gag A/E and 92%
against pol A by classical Cr-I5 release assay Whereas, 90% and 68% showed
ELISPOT positive against gag A/E and pol A, respectively. In ICCS assay, we
found that the use of 5 pfu/cell (instead of 2 pfu/cell) has improved the sensitivity of the test. In the ELISPOT vs ICCS comparison, 51 specimens from a
different group of 15 patients were tested. 65% vs 47% showed Gag-A/E specific
response, and 57% vs 31% showed po1-A specific response by ELISPOT versus
ICCS assay, respectively.
Discussion: Among Thai patients infected with HIV-1 subtype A/E with
CD4>300, ELISPOT is comparable to Cr51release assay in detecting gag A/Especific responses, but is less sensitive to detect CTL responses to pol-A. ICCS
assay seems to be the least sensitive assay in this study. This findings suggests
that in a lower frequency of HIV specific CTL response setting in vaccinees, ICCS
may not be a suitable assay for testing.
Presenting author: K Ruxrungtham, Division of Allergy and Clinical Immunology, Faculty of Medicine, Chulalongkorn University, Rama IV road, Prathumwan,

Bangkok 10330, Thailand, Tel.: [phone], Fax: [phone], E-mail: rkiat
@chula.ac.th

ThPeA7117 Highly focused anti-Nef CD8+ T cell recognition
patterns in subtype C HIV-1 infected individuals
from southern Africa
T.N. Mashishil, G. Khoury1, S. Nyoka', P. Mohubel, M. Altfeld2
C. Williamson3, R. Donovan4, H. Sheppard4, C.M. Gray1. 'National Institute for
Virology, Private Bag X4, National Institute for Virology, Sandringham, 2131,
Johannesburg, South Africa; 2Partners AIDS Research Center, Massachusetts
General Hospital and Harvard Medical School, Boston, United States; 3Division
of Medical Virology, University of Cape Town, Cape Town, South Africa;
4 California Department of Health Sciences, Richmond, United States
Background: Identity of epitope-specific CD8+ T cell responses to subtype C
Nef is important for clade-specific vaccine development. Anti-Nef CD8+ T cell responses were identified in recent HIV-1 clade C infected individuals from southern
Africa.
Method: A combination of the IFNg ELISPOT assay and intracytoplasmic cytokine staining were used to identify regions within Nef containing CTL epitopes.
Samples were obtained from 69 individuals within their first year of infection and
screened with a clade C-based set of overlapping peptides. Peptides were synthesised based on a Nef sequence from a prevailing virus in South Africa, which
is also being employed in the design of a clade C candidate vaccine, and used
for epitope screening and HLA restriction assays.
Results: 48/69 (70%) individuals recognized Nef, with 75% of responders targeting three epitope regions. Twelve individuals (25%) recognised the peptide
PGPGVRYPLTFGWCF with a mean frequency of 958 ~543 sfu/106 PBMC; eight
individuals (15%) recognised the peptide PVRPQVPLRPMTYKA with a mean
frequency of 762 +576 sfu/106 PBMC and fifteen individuals (31%) recognised
the peptide YKAAFDLSHFLKEKG with a mean frequency of 802 +568 sfu/106
PBMC. HLA-restriction assays show this epitope to be restricted by both HLAA*02 and -A*30, akin to the RSLYNTVATLY epitope in p17 Gag. Out of the three
epitope responses, there was a hierarchy of immunodominance, where exclusive recognition of the YKAAFDLSHFLKEKG was seen in 1/3 of responders;
PGPGVRYPLTFGWCF by 1/5 and PVRPQVPLRPMTYKA by 1/10 responders.
Conclusion: These data show that early-infected individuals with clade C HIV-1
display a highly focused CD8+ T cell response to Nef. Three immunodominant
epitope regions constituting 75% of Nef responses were found within a narrow
span of 73 amino acids. This immunogenic region is highly conserved between
subtypes, making it desirable to include in vaccine candidates.
Presenting author: Tumelo Mashishi, Private Bag X4, National Institute for Virology, Sandringham, 2131, Johannesburg, South Africa, Tel.: [phone],
Fax: [phone], E-mail: [email protected]
ThPeA7118 Differential CD8 T cell responses to HIV-1 in
infected monocygotic twins
R. Draenert', L. Ruiz2, B. Clotet2, B.D. Walker', J. Martinez-Picado3. 1AIDS
Research Center, MGH, AIDS Research Center, MGH, 13th Street, Bldg 149,
5th Floor, Charlestown, MA 02129, United States; 2Fundacio irsiCaixa, Hospital
Universitari Germans i Pujol, Barcelona, Spain; 3Fundacio irsiCaixa, Hospital
Universitari Germans Trias i Pujol, Barcelona, Spain
Background: Cellular immunity, especially CD8+ T lymphocyte responses have
been shown to be important in containing HIV-1-infection. HLA alleles have been
demonstrated to influence not only the viral epitopes targeted but also disease
progression. Monocygotic twins infected with the same virus provide an opportunity to assess the relationship between host and viral genetics, viral evolution
and immune containment. Here we present the immunologic analysis of identical
twins infected with the same virus.
Methods: CD8+ T cell responses were assessed comprehensively with 416 overlapping peptides spanning all HIV-1 proteins as well as optimally defined epitopes
known to be presented by their expressed HLA alleles. IFNgamma production
was measured by Elispot assay and intracellular cytokine staining.
Results: Both subjects are HLA identical, were infected at about the same time
point and envelope sequence analysis indicates that they were infected with the
same virus. CD8+ T cell responses were detected to 12 peptides in subject A and
to 29 in subject B, despite comparable viral loads and CD4 cell counts. 10 HIVpeptides were common to both and the dominant epitope was identical: a defined
optimal epitope in Nef. In subject A this was the only strong response, whereas in
subject B there were an additional 7 responses of nearly comparable magnitude,
only four of which were targeted by subject A and all at much lower levels. Full
genome sequencing is underway to determine the extent of CTL escape in both
subjects.
Conclusion: In these monocygotic twins with identical HLA type, infected with
the same virus and comparable CD4 counts and viral loads, the dominant CTL response was identical. However, subdominant responses were markedly different
in both breadth and magnitude. Further analysis including detailed sequencing
which is underway should provide insights into immune containment in chronic
viral infections

Presenting author: Rika Draenert, AIDS Research Center, MGH, 13th Street,
Bldg 149, 5th Floor, Charlestown, MA 02129, United States, Tel.: [phone], Fax: [phone], E-mail: [email protected]