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

12th World AIDS Conference

Abstracts 42142-42145 801

<200 (range <200-92,840) in semen by PCR. For 96 semen samples with both
NASBA and PCR results, 20 were positive by NASBA but undetectable by PCR
and 9 were positive by PCR only. The rank correlation for semen and plasma
viral load using the Roche PCR assay was 0.22 (p = 0.018) and 0.3 (p =.0009)
when men were on or off antiretroviral therapy, respectively. Among 150 paired
semen and plasma, 94 had detectable semen VL by either PCR or NASBA. Of
these 94, 5 (5%) had detectable semen VL when plasma VL < 200, 17 (11%)
when plasma VL was 200-10,000, and 72 (48%) when plasma VL was >10,000.
The probability of detectable semen VL was significantly associated with plasma
VL, both with and without adjustment for antiretroviral treatment (p <.001). Six
seroconverters had confirmed STDs at enrollment (3 rectal GC, 1 rectal CT, 2
syphilis) and 25 participants reported an interim STD at follow-up. However, there
was no association between semen VL and STDs, although power was limited
given no confirmed urethral STDs at enrollment and the temporal difference in
semen collection for VL testing vs. date of self-reported STDs.
Conclusions: Semen viral load in the first 1 | years after seroconversion is
moderately correlated with plasma viremia, both when individuals were and were
not on antiretroviral therapy. NASBA appears to be a more sensitive assay for
detection of virus in semen. Viral load in cervicovaginal samples will also be presented. With the small number of confirmed genital tract infections at the time of
semen collection, STDs were not associated with semen viral load. Importantly for
counseling patients about potential transmission risk, plasma viral load correlates
poorly with undetectable semen viral load.
S42142 Evaluation of laboratory performance in determining
HIV-1 RNA levels present in CDC performance evaluation
samples
Sharon Blumer1, W.O. Schalla2, T.L. Hearn2, R.J. Fehd2. 14770 Buford HWY
NE/Mailstop G23 Atlanta, Georgia 30341-3724; 2Centers for Disease Control &
Prevention Atlanta GA, USA
Objective: To monitor the quality of HIV-1 ribonucleic acid (RNA) determinations.
Methods: Replicate panels of five uniquely coded plasma samples from individual HIV-infected or HIV-uninfected donors were mailed in June, 1997 and
February, 1998 to approximately 150 laboratories enrolled in the Centers for
Disease Control and Prevention (CDC) Model Performance Evaluation Program
(MPEP). Duplicate samples from an HIV-infected donor were included in each survey panel. Prior to shipment, the CDC tested plasma samples from each donor
with HIV nucleic acid amplification kits manufactured by Chiron Diagnostics,
Organon Teknika, and Roche Diagnostic Systems. Laboratories were requested
to test these samples for HIV RNA as they would routinely test clinical specimens
and report their results to CDC on forms designed to collect data on method used
(manufactured kit or in-house procedure), lot numbers, controls used, and test
results for controls and for panel samples.
Results: The overall analytic sensitivity and specificity of the results reported for
HIV RNA determinations exceeded 97%. The median number of RNA copies/ml,
determined from results reported, varied widely depending on which manufactured kit was used. For each HIV-infected donor the median number of RNA
copies/ml varied 4-fold to 5-fold depending which manufactured kit was used.
The median RNA copies/ml, grouped by kit, was reproducible within 0.5 loglo
difference for the duplicated sample in each panel.
Conclusion: Analysis of testing results from approximately 150 MPEP laboratories suggests a need for ongoing external quality assurance for HIV RNA
determinations.
|42143 Multi-center evaluation of the ultra sensitive Roche
Amplicor HIV-1 Monitor' assay
James W. Bremer1, D. Brambilla2, C. Michels3, B. Staes1, P. Reichelderfer4.
1Rush Medical Center, 1653 Est Congrss Parkway, Chicago, IL 60612; 2New
England Research Institute, Watertown, MA; 3Data Works Development, Seattle,
WA; 4NIH/NIAID/DAIDS, Bethesda, MD, USA
Background: Recent reports in the literature have suggested that plasma viral
loads down to 50 copies/mL should be used in the clinical management of the
HIV-positive patient. This study was designed to evaluate the Ultra Sensitive
Roche Amplicor HIV-1 Monitor Assay when used under multi-center clinical trials
conditionS.
Methods: A test panel consisting of replicates of serial dilutions of normal
plasma spiked with whole HIV was sent to 9 virology laboratories participating in
the AIDS Clinical Trials Group as well as to the manufacturer and the DAIDSVirology Quality Assurance (VQA) Laboratory. HIV concentrations ranged from
25 to 500 copies/mL. Negative plasma was also included in duplicate. The ultra-sensitive Roche method was run according to manufacturer's instruction. Data
were analyzed for HIV detectability and descriptive statistics were determined.
Results: Data were collected from all 11 laboratories. There were no false positives. HIV was detected in 64% of specimens at 25 copies/mL and in 93-100%

of samples containing 50 copies/mL or higher (see table). Descriptive statistics
revealed the median standard deviation for specimens containing 50 copies/mL
or more was 0.14 but 0.27 at 25 copies/mL. Values below detection level were
treated as censored to generate the standard deviations.
Conclusion: The ultra-sensitive Roche Amplicor HIV Monitor assay is highly
sensitive and reproducible at HIV RNA levels down to 50 copies/mL. We concluded that the assay would be usable for batch testing plasma specimens in
multi-center clinical trials.
42144 1Effect of processing delay, anticoagulant and assay
(bDNA, RT-PCR) on plasma HIV RNA decay
Lynn Kirstein1, J.W. Mellors2, J.V. Giorgi3, J.B. Margolick1, J.P. Phair4,
J.S.G. Montaner5, A. Munoz1. 1Johns Hopkins School of Public Health, Room
E7012, 615 N Wolfe Street, Baltimore, MD; 2University of Pittsburgh, Pittsburgh,
PA; 3UCLA School of Medicine, Los Angeles, CA; 4Northwestern School of
Medicine, Chicago, IL, USA; 5University of British Columbia, Vancouver, BC,
Canada
Objectives: To determine the potential influence of delays in blood processing, heparin anticoagulation, and assay method on HIV RNA values in plasma
samples from the Multicenter AIDS Cohort Study (MACS).
Methods: In a first study, heparin- and EDTA-anticoagulated blood samples
were collected from 83 HIV+ individuals with detectable plasma HIV RNA and processed to plasma after delays of approximately 2, 6 and 18 hours. HIV RNA was
measured in each set of 6 samples using both bDNA (v2.0) and RT-PCR (v1.0)
assays. A second study compared HIV RNA levels, adjusted for CD4+ count and
assay method, in samples from two large HIV+ cohorts: 1,604 participants from
the MACS and 1,304 in the Vancouver study. HIV RNA values in MACS samples
(heparinized blood, collected in 1985, -6 hr processing delay, bDNA assay) were
compared to those in the Vancouver study (EDTA-anticoagulated blood, collected
in 1996-97, <6 hr delay, RT-PCR assay) after adjusting for CD4+ count. To allow
direct data comparison, MACS bDNA values were converted to those expected
by RT-PCR (Mellors et.al., 1997). P-values were based on the two-sample and
paired t-tests.
Results: HIV RNA decay (-loglo cps/ml) in heparinized blood was significant
(<0.05) after 6 hrs (bDNA: --0.12 ~ 0.11; RT-PCR: -0.06 ~ 0.16) and after 18 hrs
(DNA: 0.26 ~ 0.15; RT-PCR: -0.15 ~ 0.16), relative to samples processed within
approximately 2 hrs. Decay in EDTA-anticoagulated blood was not significant
after 6 hrs (bDNA: -0.01 ~ 0.15; RT-PCR 0.03 ~ 0.15) but was after 18 hrs
(bDNA: --0.08 ~ 0.19; RT-PCR: -0.08 ~ 0.17). Only 4.5% of samples processed
after 6 hrs lost 50% of the RNA (0.3 logio), regardless of anticoagulant and assay.
HIV RNA values in samples from the two cohorts were not significantly different
after adjusting for CD4 count and assay type.
Conclusions: The decay of HIV RNA in heparinized blood after 6 hours was
small and within the precision limits of the assay. This minor impact of decay
was confirmed by the similarity of CD4-adjusted HIV RNA values in the two large
cohorts. Our study indicates that no further correction is needed to standardize
heparin samples to what would be expected had EDTA been used.
42145 Gender differences in antiretroviral therapy received in
Ontario: A possible effect of viral load differences
Claudia Brabazon1 2, K.J. Logue2, A. Burchell2, R. Galli2. 1HIV Studies Unit 3rd
Fl Mc Murrich Bldg. 12 Queen's Park CR West Toronto ON; 2University of
Toronto Toronto, Canada
Objectives: To determine whether gender differences exist in viral load and in
the antiretroviral therapy (ART) received by women and men in Ontario.
Methods: Preliminary data in the Ontario Ministry of Health (MOH) Viral Load
Database were analysed. Entries for 666 women (9.7%) and 6218 men (90.3%)
were contained in the database. Preliminary chi-square analysis was done to
examine gender differences in: 1) whether or not ART had been received, 2)
number of drugs used in combination therapy and 3) distribution of viral load.
Results: Distributions of women and men in the viral load strata were:
(1) women: <500 copies/mL: 41.3% (n = 275), 500-1000: 5.4% (n = 36),
1,001-10,000: 21.6% (n = 144), 10,001-100,000: 22.1% (n = 147), > 100,000:
9.6% (n = 64); (2) men: <500 copies: 33.8% (n = 2103), 500-1000: 5.8% (n =
361), 1,001-10,000: 23.5% (n = 1464), 10,001-100,000: 26.6% (n = 1654), >
100,000: 10.23% (n = 636). Distributions of ART by gender were: (1) women: no
therapy 32.5% (n = 199), 1 drug 3.6% (n = 22), 2 drugs 24.6% (n = 151), 3 drugs
37.7% (n = 231), >4 drugs 1.6% (n = 10); (2) men: no therapy 25.1% (n = 1581),
1 drug 2.0% (n = 125), 2 drugs 17.1% (n = 1075), 3 drugs 42.3% (n = 2663),
>4 drugs 3.8% (n = 237). Women were more likely to have viral load below 500
copies/mL (p <.001). Differences in other viral load strata were not significant.
Women were less likely to receive any antiretroviral therapy (p <.02). Difference
in number of ART received in combination was significant (p <.001). Of those on
therapy, men were more likely to receive >3 drugs in combination (p <.02).
Conclusions: Despite universal health care and an indigent drug plan in Ontario, women are less likely to receive ART. This difference could be related to the

higher proportion of women with undetectable virus. Women are also less likely to
receive 3 or more drugs in combination than men. No significant differences exist
in other viral load strata which could account for this disparity. Gender differences
still exist in ART received even when access to care and treatment are not entirely
dependent on income.

HIV Copies/mL # Detected/Total
0 0/22
25 21/33
50 41/44
100 41/44
200 44/44
500 22/22

Percentage
(0%)
(64%)
(93%)
(93%)
(100%)
(100%)