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

12th World AIDS Conference

Abstracts 41112-41116 765

sera for the presence of anti-R7V antibody (Ab) and we looked for a correlation
with clinical situation.
Methods: 396 consentant HIV-infected patients were involved in the study:
95 women and 301 men, age ranging from 6 to 65 years old. According to the
1993 CDC classification, patients were separated as non-progressor (NP; n =
39: infected for more than 7 years with no sign of disease/CD4 count >500/ml),
asymptomatic (A; n = 57: infected for less than 7 years with no sign of disease and
CD4 > 500/ml), progressor (n = 146: infection for less than 7 years with signs of
disease and/or CD4 < 500/mi) and Long-term symptomatic (LT-symptomatic; n =
144: infection for more than 7 years with CD4 < 500/mi). Control group consisted
of 270 HIV-negative blood donors.
Results: By using a prototype ELISA, we showed that anti-R7V Ab were detected in HIV-infected patients at higher levels than in normal population (51.5%
vs 21.9%). Relative to clinical statut of patients, the frequency of positive anti-R7V
Ab level was higher in NP/A group (66.7%) compared to LT-symptomatic and progressor groups (57% and 37.2% respectively). The frequency of positive serum
for anti-R7V Ab reached 79.5% when considering the NP population alone. These
Ab were neutralizing Ab.
We showed that in vivo presence of Ab directed against the newly described
virus-associated epitope R7V is closely related with the non-progression indicating
that anti-R7V Ab constitute an efficient marker of non-progression.
41112 In vitro HIV-1 antibody induction: Testing of the Shiloov
tube
Carmen Soler Claudin1, C. Gomez Palomino2, T. Jehuda-Cohen3. 1Unidad de
Investigacion En Retrovirus H. Facultao de Quimica, Unam/Indre, SSA, Carpio
470; 2Universidad Nacional Autonoma de Mexico Mexico D.F., Mexico; 3Shiloov
Technologies, Israel
Objective: To evaluate the effectiveness of pre-incubating blood samples with an
antibody-inducing solution in diagnosing high risk population for HIV-1 exposure.
Methods: One mL heparin collected blood was incubated for 5 to 7 days in
Shiloov tubes at 37 C, 5% CO2. Supernatant was collected and adjusted for the
dilution of the blood sample with a tube solution. All adjusted samples were tested
with Genelavia Mixt ELISA; some samples were also tested with Ortho Capture,
Abbott 3rd Generation EIA, Multispot and Serodia. All the assays were run in
parallel with the original plasma sample. Samples that gave a negative plasma
serology result and a positive Shiloov supernatant result, were then gag-PCR
tested using DNA extracted from the patient's peripheral blood mononuclear cells.
Results: Two high risk groups were tested. In the first group (150 samples)
standard serology indicated a 14% HIV prevalence whereas the Shiloov supernatant results showed a 16.6% positiveness. All Shiloov positive, plasma negative
samples were gag-PCR positive. In the second group (110 samples), an HIV-1
prevalence of 5.5% was detected by serology and a 31.8% using the Shiloov tube
pre-incubation. More than 80% of the samples were tested by gag-PCR and the
results were positive. When other screening tests were used instead of Genelavia
Mixt, the results were variable, in part because it was not possible to make the
adjustment for the supernatant.
Conclusions: Detection of HIV infected people in the antibody window period
or long time exposed seronegative people is an important problem in controlling
the HIV epidemic. Testing with the Shiloov Tube can be a very useful technique
to confront these problems. Results show a much higher HIV detection, 2.6%
and 26.3%, in the 2 groups included in our study. The meaning of long term
seronegative Shiloov positive results is a new question to be answered.
41113 A new generation of HIV-diagnostic assay: Results of the
evaluation of the Enzymun-Tests" HIV combi
Eluke Faatz, F. Donie, W. Melhior, B. Upmeier, C. Seidel. Boehringer Mannheim
GMBH, Nonnenwald, Penzberg, Germany
Background: Even with the best anti-HIV diagnostic assays the early detection
of HIV infection is on average 5 to 7 days later than the detection by HIVAgassays, but performing HIV-screening with HIVAg assays in addition to anti-HIV
assays is very expensive and time consuming. We have combined both types of
assay in one determination in order to shorten the diagnostic window phase of
HIV-screening at reasonable costs.
Methods and Results: The assay is a combination of a double antigen sandwich assay (antibody detection module) comprising antigens from the env and pol
region and a monoclonal antibody sandwich assay (antigen detection module) of
four anti-p24 monoclonal antibodies. The anti-HIV/HIVAg combined assay was
applied to the Enzymun System by using Biotin-labelled antigens and anti-p24
MAbs and a Streptavidin solid phase, as well as Digoxigenin-labelled antigens
and anti-p24 MAbs and an anti-Digoxigenin-peroxidase conjugate. This assay
(Enzymun-Testo' HIV combi, Boehringer Mannheim GmbH) is earlier in the detection of seroconversion by on average 5 days compared to the best anti-HIV
screening assays. It displays very good antigen- and antibody detection with samples of different subtypes of HIV 1 (group M and 0). It also shows an excellent
HIV 2-antibody detection and some reactivity with HIV 2 p26-antigen. Specificity

with 3002 blood donors and 575 samples of hospitalised patients was found to
be 99.7% and 99.8% respectively.
Conclusion: The Enzymun-Test" HIV combi (Boehringer Mannheim GmbH)
combines the fully automated detection of anti-HIV antibodies and HIVAg in one
determination achieving a very good detection of early seroconversion paired with
a good specificity.

41114| Performance of calypte HIV-1 urine EIA in three US
populations
Dean Schoer, V. Mitteco, T. Gottfried, M. Kanar. Calypte Biomedical 1440 Fourth
Street Berkeley CA 94710, USA
Objective: To evaluate the performance of a modified Calypte HIV-1 urine EIA
test kit.
Methods: The performance of a modified Calypte HIV-1 urine EIA was evaluated with a total of 2027 urine specimens and ten dilution panels. Urine specimens
used in this study were collected both retrospectively and prospectively. The EIA
protocol was as described in the package insert with minor modifications. EIA
reactive specimens were repeated in duplicate. Repeatedly reactive specimens
were confirmed by urine western blot. In the retrospective study conducted at
Calypte, 1027 urine specimens were assayed. These specimens represented
the following categories: 1) HIV-1 seropositive, 2) HIV-1 seronegative individuals
considered at high risk for HIV infection, 3) individuals considered at low risk for
HIV infection and 4) ten dilution panels. In the prospective study, 1000 specimens
from individuals considered at low risk for HIV infection were assayed by an
independent laboratory.
Results: The data are summarized in the table below. In this study, the sensitivity and specificity of the modified Calypte HIV-1 urine EIA test kit were 100%
and 99.5% respectively. The false positive rate was lower among samples from
the low risk population than the high risk population. The combined specificity for
both high and low risk groups was 99.4%. Performance of the modified kit with 9
of 10 HIV-1 urine dilution panels was equivalent to the current kit. With one panel,
the modified kit was more sensitive, giving a positive signal one dilution earlier.
n NR RR %RR
Low Riska 1498 1490 8 0.5
High Riskb 296 293 3 1.0
HIV-1 Seropositive 228 0 228 100
a One (1) repeatedly reactive, western blot confirmed positive specimen was not included in
the table; b Four (4) repeatedly reactive, western blot confirmed positive specimens were not
included in the table
Conclusions: The modified Calypte HIV-1 urine EIA has excellent sensitivity
and specificity. The availability of a urine based test system provides a reliable,
cost effective tool for diagnosing HIV-1 infection and preventing the spread of
AIDS.
41115 1 Performance of an HIV-1, HIV-2 and HIV-1 group 0
immunoassay on the Abbott ArchitectTM 12000 analyzer
William Black, S. Stewart, A. Hoffman, J. Prostko, L. Xu. Abbott Laboratories,
200 Abbott Park Road, D-07CE AP32-2, Abbott Park, Illinois 60064-3537, USA
Objectives: To evaluate a new HIV-1, HIV-2 and HIV-1 group O assay, based
on paramagnetic microparticle-chemiluminescent technology, which has been
developed for the Abbott ArchitectT" /2000 Analyzer.
Design: Prospective, controlled internal study.
Methods: HIV-1, HIV-2 and HIV-1 group O antigens are coated onto paramagnetic particles. HIV-1, HIV-2 and HIV-1 group O antibodies in human sera or
plasma are captured and separated from the sample by magnetic attraction of
the particles. The captured antibodies are labeled with acridinylated HIV-1, HIV-2
and HIV-1 group O antigens to form antigen-antibody-antigen complexes. Captured antibody is then measured by the addition of an alkaline peroxide solution
which will decompose acridinium resulting in the emission of light. Sample handling, assay manipulation and results reporting are performed by an automated
immunoassay analyzer.
Results: This assay was equivalent to another automated HIV-1/HIV-2 assay
in detecting bleeds from ten HIV-1 seroconversion panels. A total of 128 clinically
diagnosed HIV-1/AIDS patients, fourteen (3 undiluted, 11 diluted 1:10, 1:100 or
1:500 in human plasma) HIV-1 group O samples and nine HIV-2 samples tested
positive with this assay. A total of 1578 unscreened diagnostic sera and plasma
samples were tested with this assay, and the specificity was determined to be
99.7%. Twelve of the 17 reactive samples confirmed positive for antibody to HIV-1
by Western Blot analysis.
Conclusion: This study demonstrates the ability of this combination assay to
detect HIV-1, HIV-2 and HIV-1 group O antibodies in plasma or sera with a high
degree of specificity and sensitivity.
41116 A new approach to flow cytometry based CD4 T-cell
enumeration for absolute and percentage values
Michele Bergeron12, F.F. Mandy2, T. Ding2, S. Phaneuf2. 1LCDC Bldg #6,
0603B1, Tunney's Pasteur, Ottawa, Ontario, KIA OL2; 2Bureau of HIV/AIDS &
STD, Health Canada, Ottawa, ON, Canada
Introduction: Since 1989 the Canadian Quality Assurance Programme (QAP)
has been monitoring the performance of flow cytometry laboratories based ex
clusively on their ability to measure T lymphocyte subset percentages. In recent
years, some commercial flow-based technologies have been developed to measure T-cell subset as absolute numbers. This new modified method that utilizes
clinical instruments is referred to as the single platform technology (SPT). The
goal of the National Laboratory for Analytical Cytology in Canada is to introduce
the SPT approach without compromising the quality of care of patients living with
AIDS.