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

808 Abstracts 42176-42180

12th World AIDS Conference

detection limit: 500 c/ml) in 70 samples. NASBA and AMPLICOR HIV-1 Monitor
(lower detection limit: 200 c/ml) were performed in 26 samples.
Results: The NASBA and bDNA assays each detected HIV-1 RNA in the same
44 of 70 samples tested (r: 0.880; p < 0.000). The viral load difference between
both techniques were <0.5 log10 in 27 (61.3%) specimens, between 0.5-1 log10
in 15 (34.1%) and >1 log1o in 2 (4.5%) samples. NASBA gave higher levels
of HIV-1 RNA (mean: 0.481og10) in 30 samples whereas bDNA showed higher
results (mean: 0.21 loglo) in 5. Two samples were only detected by bDNA and 9
were only detected by NASBA. 15 samples were not detected by both methods.
When viral load was measured by NASBA and AMPLICOR in 26 samples, 17
showed detectable results by both techniques (r: 0.842; p < 0.000). Difference
between the results obtained with the two assay was <0.5 loglo in 13/17 (76.5%)
samples and between 0.5 and 1 loglo in 4 samples. NASBA showed higher values
in 8 samples (mean: 0.37logio) and AMPLICOR in 9 (mean: 0.3logo1). NASBA
did not detect HIV-1 RNA in 3 samples and AMPLICOR in 1. Five samples were
not detectable by both methods
Conclusion: These results demonstrate that viral load has comparable results
for the three assays, however, NASBA tend to show values very similar to AMPLICOR and higher than bDNA. Samples with viral load below the detection limit
by any one of the two techniques should be further tested to discriminate if those
results are related to the detection limit of the tests used or to the genotypes..
42176 HIV-1 cellular infectious load in peripheral blood:
Evaluation and relationship with RNA levels in plasma
Maria Belen Bouzas,. Zapiola, J. Waisman, 2 G.R.M. Muchinik1. 1Unidad De
Virologia Hospital "FJ. Muniz" Uspallata 2272, 1282 Buenos Aires; 2Sala 19,
Buenos Aires, Argentina
Introduction: Previous studies have demonstrated that high infectious
(>100TCID/106 PBMC) viral load predict clinical progression and survival.
Objective: To compare virus RNA in plasma and cellular infectious load in
peripheral blood.
Materials and Methods: Blood samples with EDTA were collected from 57
individuals from a heterogenous group, 31 of whom were untreated (group A)
and 27 were receiving antiviral therapy (group B). Decreasing numbers of PBMC
from all patients (106, 2 x 105, 4 x 104 8 x 103, 1.6 x 103, 3.2 x 102), isolated
by Ficoll-Hypaque gradient centrifugation were cocultured in duplicate in 24 well
plates with 1 x 106 fresh PHA-stimulated PBMC from HIV-seronegative subjects.
Cocultures were maintained for 14 days and the supernatant of each dilution
was tested for the presence of p24 Ag (ABBOTT Monoclonal). Results were
expressed as TCID/106 PBMC. HIV-1 RNA levels in plasma were determined by
use of a nucleic acid-based amplification assay (NASBA;HIV-1 RNA QT, Organon
Teknika).
Results: Plasma RNA and cellular infectious load correlated well when 57
paired samples from a single time point were analyzed (n = 5, rs = 0.633, p =
0.000). For group A (n = 30, rs = 0.581, p = 0.000) and for group B (n = 27, rs =
0.699, p = 0.000) similar results were obtained. For cellular infectious load >25
TCID high RNA levels were observed in 82% of group A and in 88.8% for group
B. In 5/9 (56%) participants from group B, negative results by both methods were
obtained. In group A 6/6 (100%) subjects with no cellular infectious virus had
detectable HIV RNA in plasma
Conclusion: Despite the differences in sensitivity and variability inherent to
both techniques, pronounced correlation between cellular infectious load and
HIV RNA load (NASBA) in plasma was found. These findings also suggest that
PBMC and plasma probably are closely related compartments under particular
conditions during treatment or even during the course of infection, of HIV..
42177 Comparative evaluation of NASBA and Quantiplex HIV
RNA assays for quantification of HIV-1 in cerebrospinal
fluid
Pedro Cahn1, Ines Zapiola2, D. Rouleau3, C. Ochoa1, S. Pampurro4,
R. Glancszpigel5, H. Salomon4, C. Zala6. 1 nfectologia-Hospital Fernandez,
Angel Peluffo 3932 (1181), Buenos Aires; 2Hospital Mufiiz Buenos Aires;
4 Universiyt of Buenos Aires, Buenos Aires; 5Edyabe Buenos Aires; 6Huesped
Foundation Buenos Aires, Argentina; 3CHUM Montreal, Canada
Objectives: To compare two commercially available assays for HIV RNA quantification in CSF.
Patients and Methods: Twenty CSF samples were prospectively collected
from 15 HIV positive patients who underwent an LP for a diagnostic work-up.
CSF samples were stored at -70, until processing. NASBA (Organon, Technika)
and bDNA (Chiron 2.0) assays were performed according to manufacturer's instructions. Regression and correlation coefficients were obtained by the standard
linear regression methods.
Results: Twelve CSF, samples were available for comparison. Median HIV RNA
copy numbers were 1900 (range <400-430000) and 1260 (range <500-782300)
for NASBA and bDNA respectively. HIV RNA could be detected in 9 samples
Three samples tested below the cutoff value for both assays. A linear relationship

(log bDNA -0.13 + 0.97 log NASBA) was obtained between CSF HIV RNA levels
as determined by NASBA and bDNA r = 0.95 (p < 0.001).
Conclusions: A high correlation was found between NASBA and QUANTIPLEX
HIV RNA assays for quantification of HIV-1 in Cerebrospinal Fluid. Measurements
of CSF HIV RNA levels MASBA or bDNA appears to be suitable to evaluate vital
replication into the CNS compartment

S42178Analyzes of HIV-1 viral load (bDNA) in plasma samples in
pediatric cases
Vida Liliana Hodaral, Mirna Marcela Biglione2, A. Ceballos', D. Liberatore1,
M.M. Avila2, L. Martinez Peralta1, P. Coil Cardenas3, H.E. Solomon1. 1University
of Buenos Aires, Paraguay 2155 Piso 11, Buenos Aires; 2National Council for
Scientific Research, Buenos Aires; 3Fernandez Hospital, Buenos Aires,
Argentina
Background: For the management of antiretroviral treatment in HIV-infected
children, it is important to identify infants at risk, to make an early diagnosis and
to assess a good prognosis of disease progression. Viral load is considered as
good prognostic marker in pediatrics as in adults infected with HIV-1.
Objective: To evaluate viral load in HIV-1-infected children in Argentina using
the bDNA methodology.
Methods: Viral load in 71 samples from 55 HIV-1 infected children was analyzed by using the bDNA technology (Quantiplex HIV RNA 2.0 Assay, Chiron
Corporation, USA). Twenty three of these samples belonged to infants under 12
months of age. Children were considered HIV infected according to CDC criteria
for pediatric AIDS. Two or three plasma samples at different time points were also
quantified in 13 children to follow them up, despite of their antiretroviral therapy.
Results: Viral load in children under 12 months of age showed to be higher
(median value of 203,000 HIV RNA copies per ml) than in older children (median
= 15,800 c/ml). These values were significantly different, being percentiles 25
and 75 of 60,400 and <800,000 respectively for children under 12 months of
age and, of 2,263 and 32,575 for children older than 12 months. Only 2 samples
(8.6%) in the group of less than 12 months of age and 5 (10%) of the elders had
non detectable HIV-1 RNA. According to clinical stage there were no differences
in viral load values between asymptomatic and symptomatic patients (median
values of 27,500 (Log10 = 4.44, n = 20) and 18,500 (Log10 = 4.27, n = 28),
respectively. Follow ups were possible showing significant up/down changes from
one to another subsequent plasma sample or maintaining the HIV RNA value in
plasma constant.
Conclusions: The bDNA technique could be a good parameter to follow up
HIV infected children but it is not a marker of clinical stage. BDNA is also sensitive
enough to be a good tool helping diagnosis in children being 0-12 months old as
PCR does, specially in the first months of life.
421791 Evaluation of the chemotherapy for HIV-1 infection by an
in-house nested RT-PCR and measurement of the drug
resistance
Wu-Tse Liu, Wu Yu-Chi, Wong Wing-Wai, Chen Chuang-Tzen. 155, Li-nung St.,
2nd Sec. Taipei 11221, Taiwan
Objective: To compare the method of in-house nested RT-PCR and Roche
Amplicor kit for HIV-1 viral load and evaluation of the drug resistant variants in
chemotherapy by single-strand conformation polymorphism (SSCP) and gene
sequencing.
Design: A retrospective study and monitoring of the chemotherapy.
Methods: About 50 patients with confirmed HIV-1 infection were treated with
anti-reverse transcriptase drug and/or protease inhibitor in a period of 10 months.
Plasma samples collected within 6 hours were used for testing viral load by an
in-house nested RT-PCR and Roche Amplicor kit. Each patient was monitored
also CD4+ cell count. Patients with recurrence of viral load during the therapy
were further analyzed the drug resistant variants by SSCP and sequencing of the
gene fragments.
Results: The viral load of HIV-1 in most of the patients in combination therapy
of the drug were become undetectable in 1 month and thereafter. There were
four patients with recurrence of the virus in circulating blood. The drug-resistant
variants from these four patients were differed from one to another in SSCP
analysis and point mutation was found in the recurrent virus.
Conclusion: Out in-house nested RT-PCR is sensitive and specific for monitoring viral load in chemotherapy of HIV-1 infection. The SSCP was recommended
as a rapid diagnostic method for measurement of drug-resistant variants.
42180 Plasma viral load, CD4 count and p24 antigenemia in
HIV-infected patients
Monika Habekova1, M. MokraS2, D. Stanekova1, E. TomaSik3. 1lnst. Prev. Clin.
Med. Natl. Ref. Centre, HIV/AIDS Limbova 14, 83301 Bratislava; 2Dept. Inf. Dis.
Derer Hospital, Bratislava; 3Natl. Prog. HIV/AIDS, Bratislava, Slovak Republic
Objective: To determine the plasma viral load (RNA - HIV 1 copies), CD4 cell
counts and p 24 antigen levels in HIV 1 infected patients initiated antiretroviral
therapy and to describe the relationship of these parameters.
Methods: 13 HIV-positive patients were monitored up to 5 time over 13
months. 8 asymptomatic and 3 AIDS antiretroviral naive HIV 1 infected subjects
were treated according to criteria that assume the observed markers and clinical
stage. 6 patients were treated with two drugs combination therapy AZT + ddC and
AZT + ddl (group A), 3 patients were switched from former group and 3 patients

were initiated with triple combination AZT/3TC + ddl/ddC + indinavir (group B)
and 2 patients were monitored in absence of treatment (group C). The numbers
of viral copies were determined by Monitor HIV 1 PCR (Amplicor, Roche), CD4
cell counts were evaluated by flow cytometry and Ag p24 levels were determined
using Ag p24 HIV 1 ICD assay (DuPont).
Results: To date the decrease of viral load (VL) to baseline persisted for 5
month in 1 patient of group A, whose clinical stage has been stabilized without