Laboratory Medicine | Retrovirus Lab
Faculty
- Max Q. Arens, Ph.D., Co-director h | c
- Gregory A. Storch, M.D., Co-director h | c
Staff
Research Personnel
- Katherine Cavaletti c
- Magda M. Dwidar c
The lab was formed in the fall of 1988 as a support lab for the AIDS
Clinical Trials Unit (ACTU), an NIH-funded activity engaged in
testing of drugs potentially effective against HIV and the
opportunistic infections associated with AIDS. In addition to
testing for various virologic markers, a major part of our function
was and is to process specimens (mainly blood) for storage and/or
shipment to other labs for specialized testing pursuant to ACTU
protocols. Over the past 12 years we have expanded our repertoire
to include testing of clinical specimens for the diagnosis of HIV
infection and prognosis of HIV disease.
As the epidemic and our knowledge of HIV and AIDS have changed, so
have the laboratory tests required to support the physicians
involved in treating infected patients. The tests that we currently
perform are briefly discussed below.
HIV antibody ELISA (Barnes Blood Bank)
This is the "first line" screening assay for
antibodies in an adult that may be infected with HIV.
With today's assays, antibodies are generally detectable
about 21 days after an HIV infection in humans (range of
9 to 34 days). This assay is now performed every day in
the Barnes Blood Bank and specimens that are repeatedly
positive are sent to the Retrovirus Lab for supplemental
testing (Western Blot, see below).
HIV western blot
An antibody test with very high specificity is required
as a supplemental assay when the stakes are high as with
HIV. This assay shows the interpreter precisely which
(if any) HIV antigens have elicited an antibody response
in the patient.
HIV proviral DNA PCR assay
This is a qualitative assay which is capable of
detecting very low levels of proviral DNA in infected
lymphocytes. This assay is generally used for diagnosis
of a neonatal infection since maternal antibodies from
HIV-infected mothers mask the true infection status of
the baby. Once a patient is infected with HIV, the DNA
PCR assay will always be positive (from about day 16
on).
Viral Load (quantitative HIV RNA assay)
Progression of HIV disease is roughly proportional to
the amount of virus circulating in the blood of the
infected person. Effective treatment of HIV infection
is manifested as a decrease in the viral load. The
assay we use is PCR-based and comes in two versions,
regular (detection range = 400 to 750,000 copies of
RNA/ml) and the ultrasensitive assay (detection range =
40 to 75,000 c/ml).
HIV Genotype (sequencing of HIV RNA)
Genetic mutations occur in HIV at a very high rate and
can result in reduced susceptibility to antiretrovirus
drugs if they occur in the gene against which a drug is
directed. Thus, since 15 drugs are FDA-approved, it is
important to monitor the development of mutations so
that drugs which lose their effectiveness can be
replaced with ones that are more effective.
Quantitative HCV RNA
The Retrovirus Lab is diversifying by performing several
assays for HCV. The HCV Quant is very similar to the
above "viral load" assay for HIV. The detection
range of this assay when run on undiluted specimens is
600 to 850,000 International Units/ml. We routinely
dilute specimens 1:10 in order to expand the useful
range of the assay at the higher end and thus we shift
the detection range to 6000 to 8,500,000 IU/ml.
Undiluted specimens will be run by special request at
the time the test is ordered.
Qualitative HCV RNA
The Qualitative HCV RNA assay is used by physicians to
confirm the presence of an active HCV infection in
patients with anti-HCV antibodies (i.e. a positive ELISA
test) and to assess the efficacy of therapy for HCV.
This is the most sensitive test available for HCV RNA
and has a lower limit of detection of about 100 IU/ml.
HCV Genotype
We are now performing the HCV genotype assay (June, 00)
to aid physicians in the prognosis of HCV-positive
patients who are being treated with interferon +
ribavirin. Patients with type 1 require longer
treatment regimens and are less likely to achieve
virologic clearance. For this assay we use the PCR
amplified product from the Roche Amplicor assay in an
Innogenetics reverse hybridization (RH) assay.
The Retrovirus Lab has carefully saved thousands of specimens over
the years and we have taken measures to assure that we can find
these specimens when they are needed. We are confident that these
specimens are properly preserved and are accessible. Part of the
mission of this lab is to foster research related to HIV, HCV and
other infectious diseases that may be relevant to the patients
infected with these viruses. We have been saving specimens and
maintaining databases for this purpose. We will make both available
to interested researchers with proper approval from the Washington
University Human Studies Committee.
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SCHOOL OF MEDICINE
