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

516 Abstracts 31106-31110

12th World AIDS Conference

different hosts and running 4 to 6 parallel experiments per donor. Neutralization
activity of a patient serum (10% and 2-fold dilutions) was determined by the
reduction in the mean p24-amount as compared to the positive controls (infection
after incubation with HIV negative serum).
Results: A total of 10 patients has been analyzed so far. Of the 10 primary virus
isolates 6 were HIV-1 subtype B, 3 E and 1C; 9 isolates were of the NSI phenotype,
1 was SI. All virus isolates were dual-tropic growing on primary macrophages
as well as on primary lymphocytes. Neutralization activity of patients' sera was
different with respect to the infection of primary lymphocytes and macrophages
with the autologous virus isolates: whereas no neutralization activity was found
on lymphocytes with the early serum samples (2-8 months after infection) strong
neutralization activities were found on macrophages as early as 2 months after infection. A second serum sample obtained about 12 months after infection
showed neutralizing activities against the early virus isolate both on lymphocytes
and on macrophages.
Conclusions: Using primary macrophages as target cells in neutralization
studies with primary HIV-1 isolates allows to detect neutralization activities in
patients' sera as early as 2 months after infection. Thus, humoral immunity may
play an important role in the early control of HIV-infection.
31106 Evaluation of the HIV-inhibitory activity of seven human
mucosal fluids
Shamimh Kazmi1, S. O'Shea2, S.P. Sweet', J.E. Banatvala2, S.J. Challacombe1.
1Dept. of Oral Medicine & Pathology, 28th Fir, Guy's Tower, Guy's Hospital,
London; 2Dept. of Virology, St. Thomas's Hospital, UMDS, London, UK
Objectives: To determine levels of HIV-inhibitory activity of seven human mucosal fluids in vitro; whole, parotid and submandibular/sublingual (sm/sl) saliva,
breast milk, colostrum, seminal plasma and cervicovaginal secretions, collected
from HIV-seronegative subjects.
Methods: Samples were obtained from ten HIV-seronegative volunteers for
each fluid type, and lectin from the plant Galanthus nivalis was used as a positive
control. Anti-HIV activity was evaluated using a microtitre-based assay. The body
fluids were incubated for 1 hr at 37~C with a cell free, laboratory adapted strain of
HIV-1 which was attached to the microtitre plate with poly-l-lysine. The body secretions were subsequently washed off with PBS, and C8166 cells were added to
the fluid-treated virus. Cultures were incubated for 3 days and syncytia formation
was assessed daily to monitor HIV replication. Final assessment of HIV infectivity
was performed on day 3 by quantitation of p24Ag in the culture supernatant.
Results: Of the seven fluids tested, whole saliva, breast milk and colostrum
samples demonstrated the highest levels of anti-HIV activity (60-100% inhibition).
Seminal plasma samples showed moderate levels of activity (30-60%) and the
cervicovaginal secretions, parotid and sm/sl salivas all demonstrated consistently
low levels of activity (0-30% inhibition).
Conclusions: All seven body fluids assessed in vitro possessed HIV-inhibitory
activity, with the highest levels being present in whole saliva, breast milk and
colostrum. Identification and characterisation of these factors is important as they
have potential for use in virucidal gel formulations that could have applications in
minimising HIV-1 transmission.

Envelope peptide epitope reactivity correlated with subsequent course of disease
progression as strongly as reactivity to p24. This information may prove useful
in monitoring progression during HIV infection and perhaps help guide vaccine
development.
31108 1 Partial restoration of HIV specific neutralizing activity
(NA) of HIV infected patients receiving antiretrovial
therapy: DDI/delaviridine (DLV), AZT/DLV, DDI/AZT or
DDI/AZT/DLV
Mostafa Nokta, P. Turk. University Texas Medical Branch Galveston, Texas
77555-0835, USA
Background: HIV-infected patients progressively lose the ability to neutralize
autologous and laboratory HIV viral isolates. In this report the effect of antiretroviral therapy on the resistance of the NA of patients with HIV-infection and its
relationship to viral load and absolute CD4+ cell count were examined.
Methods: Twenty-seven patients from ACTG 261 were studied. Patients
were treated with AZT/delaviridine [ = 7], AZT/DDI[N = 5], DDI/DLV[N = 9]
or AZT/DDI/DLV[N = 7], and were examined for their NA prior to and at 24 weeks
into therapy, by an infectivity reduction assay using patient sera and autologous
virus. HIV plasma RNA was measured by RT-PCR.
Results: Fourteen of twenty seven patients at study entry had no NA (-) and
thirteen had positive (+) NA. The mean baseline CD4 cell count and HIV plasma
RNA of both groups were 317 ~ 40, 323 ~ 37 cells/mm3 (NS) and 4.65 ~ 0.18,
4.13 ~ 0.17 Log0i (p < 0.05) respectively. Nine of the 14 patients with NA(-)
at entry partially restored their NA. The infectivity reduction ranged from 0.7-3
Loglo with a mean of 1.6 ~ 0.3 Loglo. This was associated with a mean drop of
HIV plasma RNA of 0.9 Log1o ~ 0.2 and a change in absolute CD4 count from
302 ~ 40 to 437 ~ 37 cells/mm3 (p < 0.005). Patients who did not regain NA had
a mean decline in HIV RNA of -0.08 ~ 0.2 Logio and a change in CD4 cell count
from 344 ~ 93 to 259 ~ 81/mm3 (NS). The patients with restored NA received
DDI/DLV[N = 5], AZT/DLV[N = 2], DDI/AZT[N = 1] or DDI/AZT/DLV[N = 1]. Four
of 13 patients with NA (+) at entry lost their NA at week 24 (non of them were on
the DDI/DLV arm).
Conclusions: The data suggests that antiretrovial therapy can restore the
NA of sera from HIV-infected patients to the dominant autologous isolate virus.
This was associated with an increase in CD4+ T cell counts and a decline in
HIV plasma viremia. Moreover baseline viral load may predict the neutralization
status of the patients.
31109 | Neutralizing antibodies against HIV-1 primary isolates
positively correlate with CD4*T lymphocyte counts and
T cell function in long-term AIDS-free HIV-1 infected
individuals
Patrizia Carotenuto, L. Keldermans, D. Looij, F. de Wolf, J. Goudsmit. University
of Amsterdam, Hum Retrovirology, Meibergdreef 15, 1005 AZ, Amsterdam, The
Netherlands
Objectives: To assess the prevalence of neutralizing antibodies (NA) in LongTerm AIDS-free (LTAF) HIV-1 infected subjects and detect correlates with known
markers of disease progression.
Design: Cross-sectional study using sera collected 8 years after seroconversion or study entry from LTAF subjects. Longitudinal study using sera collected at
0, 0.5, 1, 2, 4, 6, 8 and 10 years after seroconversion from LTAF and, as controls,
from Rapid Progressors (RP).
Methods: Individuals with documented AIDS free HIV-1 infection for at least 8
years were evaluated for NA against heterologous HIV-1 primary isolates of both
syncytium inducing (SI) and non-SI phenotype. For the cross sectional study,
plasma viral RNA, CD41T cells numbers and T cell function were determined
on 4 consecutive samples obtained during the 8th year of follow up; CD4+T cell
decline was assessed including all the CD4*T cell counts available after the 4th
year of follow up. For the longitudinal study the same parameters were evaluated
at time points matching the selected sera.
Results: NA were detected in 49-76% of LTAF, depending on the primary
isolate tested; NA were positively associated with CD4~T lymphocyte counts (p =
0.0041) and with T cell function (p = 0.04). No correlations were found between
NA and plasma viral RNA or rate of CD4+T cell decline. Longitudinal analysis of
LTAF seroconverters sera and, for control, of RP sera, showed that, although in
both groups the majority of the subjects tested had neutralizing activity at seroconversion, NA were no longer detectable immediately thereafter. NA were again
found 2-4 years later and stably persisted in LTAF, while remained undetectable
in RP.
Conclusions: NA are prevalently found in subjects with relatively preserved T
cell function and CD4+T cell numbers and may contribute to the delay of AIDS
onset during the chronic phase of AIDS-free infection.

31110 Immunoprecipitation and neutralization of HIV isolates by
HIV patient IgG directed to a viral-associated epitope
Carole Le Contel, P. Galea, J.C. Chermann. 'Inserm Unite 322-Campus de
Luminy-BP33 163 Av. de Luminy-13273 Marseille Cedex, France
Background: We recently described the epitope (R7V) recognized by an
anti-f/2-microglobulin monoclonal antibody that neutralized divergent HIV-1
isolates (Le Contel et al, Cellular Pharmacology AIDS Sciences, 1996, 3, 68-73).

1311071

Correlation between humoral responses to HIV-1
envelope early in infection and subsequent disease
progression

Lawrence Loomis-Price', Merlin Robb2, J. Cox1, J. Mascola2, T. Vancott1,
B. Wahren3, H. Sheppard4, D. Birx2. Henry M. Jackson Foundation, 13 Taft
Court, Suite 200, Rockville, MD; 2 Walter Reed Army Institute of Research,
Rockville MD; 4California State Department of Health Services, Berkeley CA,
USA; 3Swedish Institutes for Infectious Disease Control, Karolinska Inst.,
Stockholm, Sweden
Background: This study was designed to examine the correlates of protective humoral immunity against HIV by comparing antibody responses against envelope
peptides and proteins in HIV-infected rapid and slow progressors.
Methods: The majority of the experiments were with sera from subjects in
the Walter Reed phase 2 gp160 cohort, but major findings were confirmed using the Stockholm phase 1 gp160 cohort, and the San Francisco Men's Health
Study (SFMHS) Cohort. Humoral responses in sera, drawn early in disease before progression, from rapid progressors (N = 43) were compared to responses
in similarly chosen sera from slow progressors (N-44). The assays used included: linear epitope mapping by pepscan, EIA vs selected epitopes, binding
to full-length envelope proteins (in native and denatured forms) measured by
BIACore, antibody-dependent cellular cytotoxicity directed against HIV envelope
and neutralization of primary clade B viruses grown in PBMC's.
Results: Sera from slow progressors reacted more strongly with short envelope
peptides, predominantly in gp41. Reactivity to six peptides (in C3, C4, and C5 of
gp120 and in gp41) correlated with slower progression. In a novel association,
reactivity to three peptides (in C1, V3 and C3 of gp120) correlated with faster
progression. Reactivity to an epitope in gp41 was observed more frequently in
patients heterozygous for 32 base-pair deletions in the CCR5 coreceptor. Rapid
progressors had greater gp120 native:denatured binding ratios than slow progressors. Functionally, while ADCC against gp120 did not strongly differentiate the
groups, slow progressors were distinguished by a broader neutralization pattern
against five primary viral isolates.
Conclusions: HIV-1 infected rapid and slow progressors showed differential
humoral responses against HIV envelope peptides and proteins early in infection.