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

12th World AIDS Conference

Abstracts 42120-42124 797

HIV prevalence among blood donors showed that the positivity proportion range
from 0 to 0.7%. The highest rates were found in eastern and southern parts of
the country bordering Thailand and China.
Conclusions: There is a need to develop and introduce the consensus guidelines for transfusion safety in health facilities. We need to have a cost sharing
mechanism to obtain test kits for the universal safety of blood supply system.
There is need to have more in-depth studies regarding the HIV/AIDS related risk
behaviours among the blood donors in the country. There is an urgent need to
develop best practice models for donor recruitment, education and retaining the
recruited donors for ready supply of safe blood transfusions.
42120 Incidence of HIV infection among apparently healthy
blood donors in Saudi Arabia (1985-1997)
Iman Al-Sheikh1, S.E. Fathalla2. 1PO. Box 4103, Assistant Professor Faculty of
Medicine, Dammam 31491; 2Cons. Virologist Dammam Regional Labs & B. BK
Dammam, Saudi Arabia
Objective: Kingdom of Saudi Arabia (KSA)- [a west-Asian Middle-east country
with population around 10 millions] is known for its big oil business which attracts
more than 2 millions expatriates. KSA, being a Muslim conservative country
represents an example of the effect of culture on HIV prevalence. Our aim of this
study was to find the prevalence rate of HIV infection among healthy population
in this country under their cultural environment.
Design: 134 599 blood serae were collected from healthy volunteer blood
donors for a period of 12 years (1985-1997).
Methods: * Screening tests: We used one of these ELISA kits (depending
on the then available kits): HIV-1/HIV-2 recombinant synthetic peptide antigen,
Abbott's 3 rd generation-plus EIA Assay Kits, Abbott's Germany. And/or Rapid
Elavia Mixt kits of Sanofi Diagnostics Pasteur, France.
* Confirmatory Western Blot Assay (WB): The repeatedly reactive (RR) ELISA
screened specimens were confirmed by these WB kits (depending on the then
available kit): HIV Blot 2.2 Diagnostics Biotechnology, Singapore.or/ New Lav
Blot, Sanofi Diagnostics Pasteur, France.
Results: The positive Western Blot specimens were taken as the basis of this
study

No of specimens
134,599

+ve% 95% Confidence Interval
10(0.007%) 0.0028-0.012

Conclusion: HIV prevalence rate in (KSA) was (0.007%) which is one of the
lowest world rates. This finding could reflect the cultural effect of HIV epidemiology. In which commercial sex and drug addiction play a role in HIV transmission,
both of which are culturally unaccepted inKSA. However, the blood bank services
are safe one since HIV-screening was implemented in October 1985.
S42121 Use of Murex HIV recombinant and anti-HIV-2 assays to
distinguish between HIV-1 and HIV-2 infections
Richard Bristow, J. James, R.J.S. Duncan. Murex Biotech Ltd, Central Road,
Dartford, Kent, UK
Background: Experiments were performed to determine whether the Murex HIV
recombinant (VK56) and anti-HIV-2 (GE22) assays could be used together to
differentiate between infections with HIV-1 and HIV-2. Murex HIV recombinant is
a competitive format EIA used to detect antibodies to HIV-1 and also, like most
competitive anti-HIV-1 assays, may show some reactivity with samples which
are strongly HIV-2 reactive. Murex anti-HIV-2 is a peptide-based EIA which is
intended for use only on samples which are known to be HIV-reactive.
Methods: A panel of sera from Ivory Coast (448 HIV negative, 359 HIV-1, 317
HIV-2 and 303 dually reactive by a peptide strip EIA then in use in the laboratory)
was tested using the Murex HIV recombinant and Murex anti-HIV-2 assays. An
algorithm was developed from the data to allow the Murex assays to be used
together to distinguish between infection with HIV-1 and HIV-2 and determine
likely dual infections. Discrepant results between the routine assay and the Murex
assays were investigated using alternative assays.
Results: The Murex assays gave concordant results with the routine assay
for 448/448 HIV negative sera, 359/359 HIV-1 sera, 313/317 HIV-2 sera and
263/303 dually reactive sera (as determined by the routine assay). Of the 44
discrepant samples, 41 were further tested by alternative assays (Western blot,
RIBA and InnoLIA). In the majority of cases Western blots were dually reactive
(38/40), concurring with the routine assay, whereas the majority of RIBA and
InnoLIA results concurred with the Murex assays (21/25 and 16/27 respectively).
However, Western blotting showed poor correlation with the other assays in distinguishing between single and dual infection: 68% of singly infected samples,
as determined by all of the other methods, were dually reactive in Western blots.
The Murex assay results indicated 448 HIV negative, 379 HIV-1, 333 HIV-2
and 267 dually reactive samples using the algorithm developed. Reagent costs
were also significantly lower using the Murex assays than using the routine
assay.
Conclusion: Whilst no serological test can give 100% assurance of the type of
HIV infection involved with a particular sample, the use of Murex HIV Recombinant and anti-HIV-2 assays together may allow infections with HIV-1 and HIV-2 to
be cheaply and rapidly distinguished. Because both assays use different formats
from those commonly used for screening kits they also may be used together
within WHO guidelines as part of an algorithm to confirm infection with HIV.

S42122 Medmira rapid HIV screen as a supplemental test for
rapid confirmation of EIA-based HIV positive screen
result
Sam Ratnam, Carol Head, E. Oates, V. Moulton, F. Stead. Newfound Public
Health Laboratory, PO. Box 8800, St. John's, Canada
MedMira Rapid HIV Screen (MedMira Laboratories, Hantsport, NS, Canada) is a
membrane-based immunodot assay for rapid detection of HIV-1/HIV-2 antibodies
in human serum, plasma or whole blood. This test utilizes a mixture of synthetic
peptides corresponding to conserved regions of HIV-1 and HIV-2 env genomes
as capture antigens, which are coated onto a membrane matrix. The test reaction
is visualized through a colloidal gold immunoconjugate. Studies were carried out
to determine the potential application of the MedMira test for rapid confirmation
of EIA-based HIV positive screen results, using both repository and fresh clinical
specimens. The repository panel included 256 HIV-1 positive sera (Abbott HIVAB
rDNA EIA), of which 210 were true positive (Western blot confirmed) and the
remaining 46 EIA falsely positive. With this panel, the MedMira test showed a
sensitivity of 99.6% (209/210), and specificity of 100% (46/46). Of 13,693 fresh
sera tested in a routine clinical setting, 31 sera tested positive by the Abbott EIA.
Of this, 8 were true positive (Western blot confirmed) and the remaining 23 EIA
falsely positive. In this series, the MedMira test showed a sensitivity of 100% (8/8),
and specificity of 100% (23/23). Western blot yielded indeterminate results with
half of the EIA falsely positive sera, where as the MedMira test gave a clear cut
negative results in all instances. Also, with 5 commercial seroconversion panels,
the MedMira test detected HIV antibody as early as or earlier than the reference
EIA and Western blot tests. The MedMira test required no specialized laboratory
aids, and could be completed within a minute or so.
MedMira Rapid HIV Screen is a simple reliable test. This test has the potential
to serve as a supplemental test for rapid confirmation of EIA-based HIV positive
screen results in routine clinical practice; it could be useful even in large central
laboratory settings where Western blot confirmation tends to delay the overall turn
around time. Rapid tests of this nature could be highly useful and cost effective
in many settings, and could contribute to HIV control and prevention programs.
42123 Alternative strategies for screening and confirmation of
HIV-1 antibodies in Honduras
Rita Isabel Meza. 1Laboratorio Central, 3rd Nivel Centro De Salud Alonso Svazo
Tegucigalpa, Honduras
Introduction: Standard algorythims for detection of HIV-1 antibodies are carried
out by using enzyme immuna assyas (EIA) as screening test and a more specific
test, such as Western blot (WB), for confirmation. This kind of algorythms are
difficult to perform in developing countries due to the high cost of reagents and -
lack of equipment.
Objective: to evaluate altenative algorythms to stablish cheaper and faster
diagnosis with high sensitivity and specificity.
Material and Methods: different rapid and simple tests were evaluated for
sensitivity and specificity as well as standard EIAs. Combination of these assays
were compared with the EIA/WB algoryth.
Results: Test were found to have 99% sensitivity, increasing sensitivity and
specificity up to 100% by using a combined strategy. Thus, the Ministery of
Health of Honduras decided to use one screening test, such as an EIA (Abboth
3rd generation plus) or an agglutination assay (Retrocell, Abbolt) depending the
complexity or the needs of each laboratory and an immunodot ((Multispot, Sanofi
Pasteur) for confirmartion of results. The algorythm chosen applies to WHO
strategies I and II.
Conclusions: Combined screening assays vs EIA/WB strategy lowered costs,
decreased timeconsuming to reach a diagnosis without lack of sensitivity and
specificity.
S42124 Evaluation of HIV-1 RNA assays for diagnosis and
quantitation of perinatal HIV in Thailand
Sodsai Tovanabutra1, V. Gulgolgarn2, S. Niyomthai2, K. Loryont2,
K. Junsiriyotin2, M. De Souza3, M. Robb4. 1Research Institute For Health
Sciences PO. Box 80 CMU Chiang MAI, 50202; 2Lampang Hospital, Lampang,
Thailand; 3Henry M Jackson Foundation, Bethesda MD; 4 Walter Reed Army
Institute of Research, Rockville MD, USA
Background: Early and accurate diagnosis of perinatal HIV transmission is crucial
to proper management. The importance of HIV RNA measurement in diagnosis
is less well defined, particularly in non-clade B populations. In this study we
compare the sensitivity and specificity of two viral burden methods to DNA PCR
diagnosis and provide preliminary data on the range of viral burden in 2 month
old HIV infected infants.
Methods: Dried blood spot (DBS) at 2 and 4 or 6 months old and ACD plasma
from 2 months were obtained from infants enrolled in the cohort of HIV infected
mother-infant pairs in Lampang Thailand. DNA was extracted from DBS and

subjected to DNA-PCR and plasma viral load was performed by using Nuclisense
(Organon Teknika) and Roche Amplicor HIV-1 monitor version 1.5.
Results: 13 infants have diagnostic results available for this analysis with a
transmission rate of 29.5%. The Nuclisense Assay with plasma input volume at
50 l and with an increased volume (200 pl) identified 12/44 and 13/44 infected
infants without false positive results. Roch Amplicor with plasma input volume at
10 I was able to identify infected infants. Levels of RNA assayed by Nuclisense