Bridging the Gap: Conference Record [Abstract book, International Conference on AIDS (12th: 1998: Geneva, Switzerland)]

522 Abstracts 31134-31139

12th World AIDS Conference

113* / 31134 Functional lymphocyte reconstitution and HIV-1
specific T cell responses during highly active
antiretroviral therapy (HAART)
Oscar Pontesilli1, S. Kerkhof-Garde1, N.G. Pakker1, D.W. Notermans2,
M.T.L. Roos2, S.A. Danner2, F. Miedema. 1 Clin. Viro-lmmunology, C.L.B.,
Presmanlaan 125, 1066 CX, Amsterdam; 2NATEC, University of Amsterdam,
Amsterdam, Netherlands
Objectives: To evaluate T cell function and changes of HIV-1 specific T cell responses during combination therapy with ritonavir, zidovudine (AZT), and lamivudine (3TC).
Design: Longitudinal study.
Methods: Peripheral blood mononuclear cells (PBMC) from 6 HIV-1 infected
patients (baseline values: 40-323 CD4+ T cells/il; 5.0-6.1 log HIV-1 RNA
copies/ml) were obtained before HAART administration (week - 1) and after 5,
22, and 42 weeks of treatment. In vitro lymphoproliferative responses (LPR) to
C. albicans, tetanus toxoid, and M. tuberculosis, as recall antigens (Ag), and
to recombinant HIV-1 p24 and p17 were measured by 3H-Thymidine incorporation. HIV-1 Gag- and reverse transcriptase (RT)-specific cytotoxic T lymphocytes
(CTL) were measured as frequency of precursors (CTLp) after in vitro Ag-specific
stimulation and standard 51Cr release assays.
Results: LPR to recall Ag, undetectable before therapy, were found in all patients during HAART comparable to those of a reference group of HIV-1 infected
long-term asymptomatics. Increased responses were detected within the first 22
weeks and declined later in 2 of 6 patients. Weak pre-treatment LPR to HIV-1 Ag
moderately increased in 3 patients during treatment, but the change was not significant. In these late stage patients, HIV-1 specific CTL were undetectable before
HAART. During treatment low HIV-1 specific CTLp frequencies (0-51 CTLp/106
PBMC) were found.
Conclusion: Improved T lymphocyte function during HAART was achieved,
probably as a result of both T lymphocyte recirculation from lymphoid tissue
and lower virus-related inhibitory soluble factors and cytokines; reduction of
HIV-1 antigenic mass resulted in a minor increase of measurable HIV-1 specific
responses.
31135 Recognition of two overlapping CTL epitopes by CTL
from a long-term non-progressing HIV-1 infected
individual
Thomas Harrer, E. Harrer, P. Barbosa, R. Wagner, M. Feinberg, S. Buchbinder,
B.D. Walker. Dept. of Medicine 3, Univ. of Erlangen, Erlangen; University of
Regensburg, Regensburg, Germany; Gladstone Institute, San Francisco CA;
Dept. of Public Health, San Francisco CA; AIDS Center, Mass. General Hospital,
Boston MA, USA
Background: HIV-1 infection has been shown to elicit strong CTL responses
in some infected persons, but few data are available regarding the relationship
between targeted epitopes and in vivo viral quasispecies.
Methods: HIV-1 specific CTL response was analyzed in a long-term non-progresser infected for 15 years with a CD4 count persistently >500 cells/pl. CTL
activity of fresh PBMC or peptide stimulated cell lines was measured against autologous B-LCL either infected with recombinant vaccinia viruses or labeled with
peptides. Autologous HIV-1 was sequenced from plasma or culture supernatants.
Results: The dominant CTL response was directed against 2 overlapping Gag
CTL epitopes in an area of p17 known to be essential for viral replication. The
nine-mer SLYNTVATL (aa 77-85) was recognized in conjunction with HLA A2,
whereas the overlapping eight-mer TLYCVHQR (aa 83-91) was recognized by
HLA All-restricted CTL. Analysis of viral sequences both in PBMC and plasma
revealed sequence variation in this region which did not affect viral replication but
decreased recognition by the All-restricted CTL response, with maintenance of
the A2-restricted response.
Conclusion: These results indicate that an essential region of the p17 protein
can be targeted by CTL through 2 different HLA molecules, and that immune
escape from CTL recognition can occur without impairing viral replication. In
addition, they demonstrate that antigen processing can allow for presentation
of overlapping epitopes in the same infected cell, which can be affected quite
differently by sequence variation.
31136 Phenotypic characterisation of T-cell expansions in HIV
infection
Angel Jaramillo1, J.J. Zaunders1, A.D. Kelleher1, D.A. Coope2. 1Centre for
Immunology, St. Vincent's Hospital, Victoria ST, Sydney; 2National Centre for
HIV Epidemiology & Clinical Research, Australia
Aim: To analyse the T-cell receptor V-beta chain (TCRBV) repertoire at various
stages of HIV infection and phenotypically characterise expanded BV subsets.
Methods: 3-colour flow cytometry was used to analyse expression of 16
TCRBV subsets on CD4+ and CD8+ T-cells in patients with chronic HIV infection
(HIV+) (n = 26); primary HIV infection (PHI) (n = 18); and HIV negative controls (n

= 13). Expansions of TCRBV subsets were identified where BV expression was
> 10% of CD4 or CD8 T-cells. Expanded BV subsets were then examined for the
expression of CD38, HLADR, CD28 and CD45RO and compared to one other
non-expanded BV subset from the same individual.
Results CD4+ BV expansions were found in 11/26 HIV+; 2/18 HIV seroconverters; and 1/13 controls. CD8+ BV expansions were found in 6/26 HIV+; 6/18 HIV
seroconverters and 2/13 controls. In all cases, when compared to non-expanded

subsets, these BV expansions displayed differential expression of one or more of
the activation markers, CD38, HLADR and CD45RO. Both CD4+ and CD8+ BV
expansions were down regulated for expression of CD28 (p < 0.0002 compared
to non-expanded BV subsets). In 8 HIV+ individuals, BV expansions persisted
for >1 yr and were unaffected by antiviral therapy. Expansions in control subjects
also displayed decreased CD28 expression, but no differences in other markers.
Conclusions: HIV infection is associated with disruptions of TCRBV repertoire which includes the appearance of expanded TCRBV subsets. Such BV
expansions display an activation phenotype distinct from other T-cells within an
individual repertoire and are consistently down-regulated for CD28 expression.
Such a differential activation phenotype of expanded BV subsets suggests a
unique function for these cells and may be indicative of chronic in vivo stimulation
by HIV or other pathogens.
31137_ Cytotoxlc T lymphocytes (CTL) recognition of
drug-induced variants in HIV-1 reverse transcriptase
Brigitte Autran1, J. Duntze1, A. Samril, G. Haas1, C. Katlama2, P. Debre1. 'Lab.
Immunologie Cellulaire, URA CNRS 625, Bat. Cervi CH Pitie-Salpetriere 83,
2Dep. Maladies Infectieuses et Tropicales CH Pitie-Salpetriere Paris, France
Objective: To evaluate the impact of the mutations (RT184 and 215) induced
by RT-inhibitors (RTI) in immunodominant regions recognized by cytotoxic T
lymphocytes (CTL) specific for the HIV-1 Reverse Transcriptase.
Methods: The evolution of HIV-specific CTL responses was followed over
4 years in 50 patients from the French IMMUNOCO cohort (CD4+ counts:
1050-150/mm3). CTL recognition of vaccinia virus encoding RT minigenes and
RT peptides was tested after stimulation with autologous irradiated PHA blasts or
specific peptides short peptides (9-mer) containing the RT 184 and 215 mutations
were used in analysis of MHC-peptide binding, and in CTL assays and limiting dilution analysis in selected HIV-infected patients with appropriate HLA haplotypes.
Results: CTL specific for RT were detectable in 80% patients at all stages
of the infection and were directed against the NH2-half [1-292] or the C-half
[292-560] in 79% and 54% cases respectively. In 11 patients treated with RTI
frequency of CTL recognition of the NH2-half regions felt down to 18% while
C-half region was still recognized in 72% patients. Drug induced mutations poorly
affected antigen processing or peptide-HLA binding. Both wild type and mutant
peptides were immunogenic and recognized by CTLs although with low pCTL
frequencies as shown in LDA.
Conclusion: CTL recognition of HIV-1 RT is maintained with disease progression and RTI therapy. RTI-induced mutations 184 and 215 are not deleterious for
the immunogenicity of the surrounding CTL epitopes. These data suggest that
emergence of these mutations does not reflect an immune escape phenomenon
but rather differences in selective pressure between anti-viral drugs and CTL in
this region.
31138 Cytotoxic T lymphocytes and viral load in HIV-infected
children over five years of age: Influence of CCR5
genotype and antiretroviral treatment
Florence Buseyne1, G. Janvier1, M. Burgard2, D. Scoot-Algara1, J.P. Teglas3,
S. Blanche4, Y. Riviere1. Institut Pasteur Unite VI.C., Paris Cedex 15; 2Hopital
Necker Lab Virologie, Paris 15; 3Hopital Du Kreml In-Bic Etre, Kreml In-bicetre;
4Hopital Necker Unite Immuno & Hemato, Paris 15, France
Background: Approximately 80% of perinatally HIV-infected are asymptomatic in
early life and survive after five years of age. Some children remain asymptomatic
for 8 years or more. A group of 40 children over five years of age were followed
for their viral load, CTL activities and lymphocytes subsets. We study these
parameters in relation to the CCR5 genotype and to the introduction of potent
antiretroviral therapy.
Methods: Plasma viral load was measured by the branched DNA technique.
Lymphocytes subsets were analysed by cytofluorometry. CTL activities were determined by a standard chromium release assay against HIV proteins. CCR5
mutant allele were detected by a PCR based assay.
Results: 1/ At a median age of 8.3 years, children heterozygous for the mutant
CCR5 allele (A32) had lower viral load (p < 0.01) and higher CD4+% (p < 0.07)
than wild-type homozygous children. Heterozygosity had no effect on CD8+ T
lymphocytes numbers and on their HIV -specific CTL activities. 2/ Preliminary
studies show that treatment of children with a combination of three antiviral
drugs lead to reduction of plasma viral load, increase in CD4+ % and to the
down-regulation of activation markers, but did not modify the CTL response.
Conclusion: Heterozygosity for the CCR5 A32 allele had a beneficial effect on
viral load and CD4+ % after 8 years of infection in children, but had no effect on
the virus-specific CTL. Tritherapy generally improved virologic and immunologic
parameters, but did not seem to modify the HIV-specific CTL response.
31139 | Cross-clade HIV-1 specific cytotoxic T lymphocyte (CTL)
activity in HIV-1-infected Ugandan adults

Catherine Othieno, H. Cao, M. Okello, E. Katongole-Mbidde, P. Mugyenyi,
B. Walker, J. Ellner. Joint Clinical Research Centre PO Box 10005 Kampala,
Uganda; Massachusetts General Hospital Boston MA; Case Western Reserve
University Cleveland OH, USA
Objective: To assess HIV-1 specific CTL activity among HIV-1 infected Ugandan
adults.