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Medical Forum / Diseases and Disorders / AIDS / March 2005

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ELISA and Western Blot two heads from same monster industry

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George DeCarlo - 07 Mar 2005 16:37 GMT
The following are from the ELISA test insert and the insert from the
Western Blot test:

"LIMITATIONS OF THE PROCEDURE (of ELISA)

The (Abbot Laboratories) [Abbot] HIVAB HIV-1 EIA antibody procedure and
the Interpretation of Results must be followed closely when testing for
the presence of antibodies to HIV-1 in plasma or serum from individual
subjects. Because the EIA was designed to test individual units of
blood or plasma, most data regarding its interpretation were derived
from testing individual samples. Insufficient data are available to
interpret tests performed on other body specimens, pooled blood or
processed plasma, and products made from such pools: testing of these
specimens is not recommended.

Abbot HIVAB HIV-1 EIA detects antibodies to HIV-1 in blood and thus is
useful in screening blood and plasma donated for transfusion and
further manufacture, in evaluating patients with signs or symptoms of
AIDS, and in establishing prior infection with HIV-1. Clinical studies
continue to clarify and refine the interpretation and medical
significance of the presence of antibodies to HIV-1. For most uses it
is recommended that repeatably reactive specimens be investigated by an
additional more specific, or supplemental test. A person who has
antibodies to HIV-1 is presumed to be infected with the virus and
appropriate counseling and medical evaluation should be offered. Such
an evaluation should be considered an important part of HIV-1 antibody
testing and should include test result confirmation on a freshly drawn
sample.

AIDS and AIDS-related conditions are clinical syndromes and their
disgnosis can only be established clinically. EIA testing alone cannot
be used to disgnose AIDS, even if the recommended investigation of
reactive specimens suggests a high probability that the antibody to
HIV-1 is present. A negative test result at any point in the
investigation of individual subjects does not preclude the possibility
of exposure to or infection with HIV-1. The risk of an asymptomatic
person with a repeatably reactive serum sample developing AIDS or an
AIDS-related condition is not known.

Data obtained from testing persons both at increased and at low risk
for HIV-1 infection suggest that repeatably reactive specimens with
high absorbance on EIA are more likely to demonstrate the presence of
the HIV-1 antibodies by additional more specific, or supplemental
testing. Reactivity at or only slightly above the cut-off value is more
frequently nonspecific, especially in samples obtained from persons at
low risk for HIV-1 infection; however, the presence of antibodies in
some of these specimens can be demonstrated by additional more
specific, or supplemental testing."

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Now from the test to confirm the above test. CONFIRM?!

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"LIMITATIONS OF THE PROCEDURE (of Western Blot)

1. The assay must be performed in strict accordance with these
instructions to obtain accurate, reproducible results.

2. Although a Positive result may indicate infection with the HIV-1
virus, a diagnosis of Acquired Immunodeficiency Syndrome (AIDS) can be
made only if an individual meets the case definition of AIDS
established by the Centers for Disease Control. A repeat test on an
independent sample should be considered to control for sample mix-up or
operator error, and to verify a positive test result.

3. Individuals with HIV-1 infection may present incomplete patterns due
to the natural history of AIDS or other immunodeficiency states, e.g.:

a. AIDS patients may lose antibody reactions to p24 & p31;

b. Infected infants may fail to seroconvert;

c. Individuals who have recently seroconverted may display incomplete
band patterns;

d. Infected patients with malignancies and individuals receiving
immunosuppressive drugs may fail to develop a Positive result;

e. Individuals infected with HTLV-I/II or HIV-2, may exhibit incomplete
cross-reactivity.

4. Since reactivity of any degree with any of the virus-specific
proteins identified on the strip is possible evidence of antibodies to
HIV-1, all samples interpreted as Indeterminate should be repeated
using the original specimen. Do not use this kit as the sole basis of
disgnosis of HIV-1 infection. In addition, it is recommended that
samples interpreted as Indeterminate be retested after six months,
using a fresh specimen.

A Negative result does not exclude the possibility of HIV-1 infection.
Antibody testing should not be used in lieu of donor self-exclusion by
blood collection establishments."
PaulKing - 19 Mar 2005 09:59 GMT
AS OF 1999, IT WOULD SEEM THE ROCHE AMIPLICOR HIV-1
MONITOR TEST IS THE MOST POPULAR PCR "VIRAL LOAD" TEST.

"The Roche Amplicor HIV-1 Monitor(TM) test kit,  approved by the FDA, was
used by more than 70% of  the laboratories reporting results."

http://www.phppo.cdc.gov/MPEP/pdf/rna/9902rnaa.pdf

The test kit list: http://www.fda.gov/cber/products/testkits.htm 

AMPLICOR HIV-1 MONITOR(TM) TEST

"The AMPLICOR HIV-1 MONITOR Test is not intended to be used  as a
screening test for HIV or as a diagnostic test to confirm
the presence of HIV infection."

http://www.fda.gov/cber/pma/p9500054.htm
http://www.fda.gov/cber/PMAlabel/P9500054LB.pdf 

NucliSens(R) HIV-1 QT -- HIV QT Nov. 13, 2001

"The NucliSens(R) HIV-1 QT assay is not intended to  be used as a
screening test for HIV-1 nor is it to  be used as a diagnostic test to
confirm the presence  of HIV-1 infection."
http://www.fda.gov/cber/pma/p0100010.htm
http://www.fda.gov/cber/pmalabel/P0100010LB.pdf 

COBAS AmpliScreen HIV-1 Test, version 1.5
Approval Date: 12/19/2003

"This test is not intended for use as an aid in diagnosis."

http://www.fda.gov/cber/products/hiv1roc121903.htm
http://www.fda.gov/cber/label/hiv1roc121903LB.pdf 

Procleix(R) HIV-1/HCV Assay -- IN0076-01, Rev. A
Approval Date: 6/4/2004

"The Procleix HIV-1 Discriminatory Assay may be used as an  aid in the
diagnosis of HIV-1 infection." 

http://www.fda.gov/cber/products/hivhcvgen060404.htm
http://www.fda.gov/cber/label/hivhcvgen060404LB.pdf

GENETIC SYSTEMS (TM) rLAV EIA

"The rLAV EIA is intended to be used as a screening test for  donated
blood or plasma and as an aid in the diagnosis of  infection with HIV-1."

http://www.fda.gov/cber/products/hiv1gen062998.htm
http://www.fda.gov/cber/sba/hiv1gen062998S.pdf

VIRONOSTIKAT(R) HIV-1 PLUS O MICROELISA SYSTEM

"System is intended for use as an aid in diagnosis of  infection with
HIV-1. It is not intended for use in  screening blood donors."

http://www.fda.gov/cber/pma/P020066.htm
http://www.fda.gov/cber/pmalabel/P020066LB.pdf

THE CAMBRIDGE BIOTECH HIV-1 WESTERN BLOT KIT

"Accurate diagnosis of HIV-1 infection is important  in determining an
individual's risk for  developing AIDS. Accuracy is complicated by
false-positive and false-negative (EIA) results. It  would appear that in
some limited infections, a  compartmentalized response occurs in which
expression of HIV-1 or its respective Immune  response is limited to a
restricted number of organs  and tissues.(17)"

"Slight ambiguities exist in the designation of the  molecular weights of
the HIV-I antigens. The designations  listed in Figure 1 have been
established by both internal  testing with known markers and consensus of
published
literature.(5-10)"

"Although a blot POSITIVE for antibodies to HIV-1  indicates infection
with the virus..."
"POSITIVE blot results using any specimen type  (serum, plasma, or urine)
should be followed with  additional testing. Such testing may rely on
alternative test methods or specimen types. The  clinical implications of
antibodies to HIV-1 in an  asymptomatic person are not known."

"The sensitivity ... using urine was evaluated by  comparing the urine
results to the results obtained  from testing paired serum specimens
collected from  individuals who were HIV-1 seropositive and from
individuals clinically diagnosed as AIDS patients."

http://www.fda.gov/cber/products/hiv1cam052898.htm
http://www.fda.gov/cber/label/hiv1cam052898Lb.pdf 

OraSure(R) HIV-1 Western Blot Kit

"The OraSure HIV-l Western Blot Kit is an in vitro  qualitative assay for
the detection of antibodies to  individual proteins of the Human
Immunodeficiency  Virus Type 1 (HIV-l) in human oral fluid specimens
obtained with the OraSure HIV-l Oral Specimen  Collection Device.

The OraSure HIV-l Western Blot Kit is not intended  for use with blood,
serum/plasma or urine specimens,  or for screening or reinstating
potential blood donors."
http://www.fda.gov/cber/pma/P950004.htm
http://www.fda.gov/cber/pmalabel/P950004Lb.pdf 

Reveal(TM) Rapid HIV -1 Antibody Test
"The Reveal" Rapid HIV -1 Antibody Test is intended for  use as a
point-of-care test to aid in the diagnosis of  infection with HIV -1. This
test is suitable for use in  multi-test algorithms designed for
statistical validation of rapid HIV test results."

http://www.fda.gov/cber/pma/p000023.htm
http://www.fda.gov/cber/pmalabel/P000023LB.pdf
 
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