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

260 Abstracts 21106-21110

12th World AIDS Conference

212*/21106 Distinctive patterns of CD8 T cell clonal dominance
identified in HIV-infected children by CDR3 length
analysis of T cell receptor (TCR) V/3 repertoire
Savita Pahwa1, Soe Than, M. Kharbanda, C. Vivek, C. Surendra, S. Bakshi.
North Shore University Hospital - NYU School of Medicine, 1Dept. Ped.
Immunology, Rm 303 Res. Bldg., 350 Community Drive, Manhasset, NY, USA
Objectives: To investigate the TCR V/ repertoire in CD8 T cells in HIV-infected
children
Rationale: Following primary infection in HIV-infected adults, the pattern of
clonal dominance in specific TCRV/ family genes in CD8 T cells correlate with
the rate of CD4 decline, plasma HIV RNA levels and cytotoxic T cell (CTL) responses. As HIV-infected children often manifest decreased CTL we investigated
their CD8 VI repertoire to determine clonal dominance pattern.
Methods: CDR3 length analysis of TCR V/ genes was determined in purified
CD8 T cells by multiplex PCR in a cohort of 21 HIV-infected children, age range
from 0.75 to 14 years (mean 7.9 yr.). Children were classified into immune categories 1 and 3 based on their CD4%. Clonal dominance pattern was defined
on the basis of numbers of TCR Vp families involved: >3, major; 1-2, minor; 1,
single; 0, none. Stimulation indices (SI) in lymphocyte proliferation assays (LPA)
with recall antigens (tetanus and candida) were performed concurrently.
Results:
Children n CD8 T-cell clonal dominance pattern LPA, mean SI
immune category None Single Minor Major Candida Tetanus
1 (>25%) 10 0 0 2 8 108 93.7
3 (<15%) 11 6 3 0 2 12.9 9.6
In children in immune category 1, a pattern of major clonal dominance in CD8
T cells was noted in 80% of patients and none had single or no clonal dominance.
The latter pattern however was predominant (82%) in children in immune category 3. A marked difference in LPA to recall antigens was evident between the 2
groups.
Conclusions: A pattern of major CD8 clonal dominance is associated with
a preserved immune system and appears to be lost with disease progression.
We speculate that functionally, these clones represent HIV-specific effector cells
and this issue is being addressed in in vitro propagated, specific VP clones.
The influence of highly active antiretroviral therapy on Vp specific CD8 clonal
expansions is currently under investigation.
11*/21107 CCR-5 genotype may confer resistance to
mother-to-child HIV-1 transmission
Sean Philpott1, H. Burger1, T. Charbonneau1, R. Grimson2, S. Nachman2,
A. Kovacs3, B. Weiser1. 1 Wadsworth Center, NYS Dept of Health, 120 New
Scotland Ave, Albany, NY 12208; 2State University of New York; 3USA-LA
County Medical Center, USA
Background: Recent studies have identified a human gene which plays a role
in susceptibility to HIV-1 infection. The gene codes for CCR-5, the co-receptor
for macrophage tropic strains of HIV-1, and a homozygous deletion in this gene
confers a high degree of natural resistance to sexual and parenteral transmission of HIV-1. The frequency of the mutant gene varies among different racial
populations.
Methods: To determine whether CCR-5 plays a role in mother-to-child transmission of HIV-1, we studied the CCR-5 genotype of 552 children born to HIV-1
infected mothers in the United States and determined the HIV-1 infection status
of the children. Genotypes were determined by PCR and restriction analysis.
Results: 13% of the children were Caucasian, 30% were Latino, and 56% were
African American, and 1% were of mixed or other ethnic ancestry, a distribution
which reflects the ethnic make-up of infected women in the US. Approximately
27% of the children in each ethnic group were HIV-1-infected. The frequency of
the mutant allele in the three main racial groups was 0.08 in Caucasians and 0.02
in both Latinos and African Americans. Two uninfected Caucasians (3.77%) and 2
uninfected Latinos (1.68%), but no African Americans, were homozygous for the
mutation. No HIV-l-infected children were homozygous for the mutation. In Latinos and Caucasians the number of uninfected children who were homozygous for
the mutation was significantly greater than that predicted by the Hardy-Weinburg
equilibrium (p = 0.001 for Latinos and p = 0.04 for Caucasians).
Conclusion: This study suggests that the homozygous deleted CCR-5 genotype may confer a high degree of protection from mother-to-child transmission of
HIV-1. These data also suggest that sexual, parenteral, and vertical transmission
involve processes that utilize CCR-5 as a coreceptor for primary HIV-1 infection.
Therefore, blocking the CCR-5 receptor may provide an additional strategy to
prevent mother-to-child transmission of HIV-1.
268*/21108 Increased turnover of both CD4 and CD8 T-cells in
HIV-1 infection until end stage disease

Nicolas Sachsenberg1, A.S. Perelson2, S. Yerly1, G.A. Schockmel1, D. Leduc3,
B. Hirschel4, L. Perrin1. 'Laboratory of Virology, University Hospital, Geneva;
4Division of Infections Diseases, Geneva, Switzerland; 2Los Alamos National
Laboratory, Los Alamos, NM, USA; 3Annemasse Hospital, Annemasse,
France
Background: There is no consensus on CD4 and CD8 T-cell turnover in HIV-1
infection, and there is limited data on physiological T-cell turnover.

Methods: We determined CD4 and CD8 T-cell turnover by measuring the proliferation antigen Ki-67 in T lymphocytes of 42 HIV-1 infected, untreated individuals
and 23 healthy controls.
Results: In HIV-1 infected individuals, mean growth fractions of both CD4 (6.5
~ 4.8%) and CD8 T-cells (4.3 ~ 2.9%) were 4 to 8-fold elevated as compared to
healthy controls. CD4 and CD8 T-cell growth fractions were inversely correlated
with CD4 counts, suggesting a compensatory mechanism to counterbalance CD4
T-cell loss. In HIV-1 infected patients, mean daily CD4 T-cell turnover (2.9 ~ 2.3
x 109 cells/day) was elevated 2 to 3-fold as compared to controls (1.5 ~ 0.9 x
109 cells/day). High CD4 T-cell turnover (3.9 ~ 2.2 x 109 cells/day) was detected
in patients with >200 CD4 counts and low viral loads (4.0 ~ 1.0 log HIV RNA/ml),
whereas lower than normal CD4 T-cell turnover (1.1 ~ 1.0 x 109 cells/day) was
detected in patients with <200 CD4 counts and high viral loads (5.1 ~ 0.8 log HIV
RNA/ml). In contrast, mean CD8 T-cell turnover, driven by peripheral expansion
of CD8 memory T-cells, was elevated 4 to 7-fold throughout all stages of disease
(4.5 ~ 3.6 x 109 cells/day; controls: 0.7 ~ 0.5 x 109 cells/day).
Conclusions: Mean CD4 T-cell turnover as determined by the proliferation
antigen Ki-67 is increased in HIV-1 infected patients, but is more prominent in patients with high CD4 counts and low viremia, suggesting that direct virus induced
lysis of CD4 T-cells is only one of the mechanisms in CD4 T-cell loss. Mean
turnover of CD8 T-cells exceeds that of CD4 T-cells by 2 to 3-fold throughout all
stages of disease.
335*/21109 Repertoire of chemokine receptor expression in
the female genital tract: Progesterone increases
CCR5, CXCR4, and CCR3 expression
Bruce Patterson1, A. Landay2, J. Andersson3, H. Behbahani3,
M.A. Czerniewski2, Z. Burki4, P. Garcia4. 1333 East Superior Street 410
Chicago, IL 60611; 2Rush Medical College Chicago, IL; 4Norwestern University
Chicago, IL, USA; 3Karolinska Institute, Stockholm, Sweden
Background: Sexually transmitted diseases (STD), genital ulcer disease (GUD)
and progesterone therapy increase susceptibility to lentivirus transmission. We hypothesize that these conditions upregulate coreceptors specific for macrophagetropic HIV-1, the primary sexually transmitted HIV-1 isolate.
Methods: Quantitative kinetic RT PCR was developed to determine the in
vivo expression levels of CCR5, CXCR4, CCR3, CCR2b, and the CMV encoded
US28 in peripheral blood (PBMC's) and cervical biopsies from twelve women with
and without STD's, GUD, and progesterone predominant conditions. Localization
of expression was performed using immunofluorescence or fluorescence in situ
amplification and image analysis.
Results: CCR5 mRNA expression was significantly increased in the ectocervix
(p <.01, student t-test). CCR5 mRNA expression was ten fold greater than
CXCR4, 20 fold greater than CCR2b, and 100 fold greater than CCR3. In peripheral blood, CXCR4 expression was significantly increased (p <.02). CXCR4
mRNA expression was 1.5 fold greater than CCR5, 10 fold greater than CCR2b,
and 15 fold greater than CCR3. US28 was not expressed in any of the biopsies
in spite of expression in PBMCs from five individuals. CCR5 was significantly
increased (p <.02) in biopsies from women with STD's and others who were progesterone predominant. In vitro studies demonstrate that progesterone increases
CCR5, CXCR4, and CCR3 expression and decreases CCR2b expression in
lymphocytes and monocytes/macrophages.
Conclusions: CCR5 is the predominantly expressed HIV-1 coreceptor in the
female genital tract under normal, inflammatory, and progesterone predominant
conditions. CCR5 in the genital tract is selectively upregulated by STD's, GUD,
and progesterone. CD4+, CD45RO' T-cells and macrophages were the predominant CCR5 expressing cells in biopsies from women with STD's and GUD.
Characterization of chemokine receptors at the tissue level provides important
information in identifying host determinants of
21110 Molecular and biological characteristics of HIV-1 strains
from patients with AIDS dementia complex
Rafael Jozwiak, T. Ng, R. Osborn, A.L. Cunningham, N.K. Saksena. Retroviral
Genetics Lab WIHR CVR 2nd Floor, Westmead Hospital, Australia
Objectives: To study the biological properties and molecular architecture of HIV-1
strains implicated in AIDS dementia complex. (ADC)
Design: A systematic study to identify neurotropic variants of HIV-1 in the V3
region (a region important in viral tropism and neutralization) and the nef gene
(crucial for viral replication).
Methods: The HIV-1 V3 region and nefgene quasispecies from the peripheral
blood and six different regions of the brain (right and left frontal; right and left
parietal; and right and left occipital), were investigated in two patients who died of
ADC. The viral isolates from the blood and brain of both patients were cultured in
PBMC's, monocytes and monocyte derived macrophages to yield the replicative
kinetic data. Cloning was achieved using the PGEM-T vector and the sequencing
performed on an ABI automated sequencer. The phylogenetic analyses were
done using maximum parsimony and neighbour joining methods.

Results: Cloning and sequencing of these regions suggested the presence of
genetically unique sequences in different regions of the brain, but showed homogeneous sequences in blood, suggesting the radiation of viral quasispecies after
crossing the blood brain barrier. Furthermore, there appeared to exist significant
differences in their physical properties; such as net charge, hydrophylicity and
secondary structure. Culture studies of viral strains from blood and brain, further
supported the evidence for distinct neurotropic variants during HIV-1 neuropatho