


INVESTORS CONTACT:  PAMELA SHERRY
                    336.584.5171, EXT. 4855

MEDIA CONTACT:      HAYLEY SOFFER, MS&L     SARRA SCHAAB, MS&L
                    212.213.7067            212.213.7056





                    HIV DRUG RESISTANCE TESTING PROCEDURES
                      NOW AVAILABLE IN THE  UNITED STATES
            --CLINICAL TRIALS INDICATE RESISTANCE TESTING PREDICTS
                        EFFECTIVENESS OF DRUG THERAPY--

Burlington, NC, July 20, 1998 - Laboratory Corporation of America-Registered
Trademark-Holdings (LabCorp-Registered Trademark-) (NYSE:LH) and VIRCO, today
announced that the Antivirogram-Trademark- and the VircoGEN-Trademark, two new
diagnostic testing procedures enabling physicians to evaluate resistance of
HIV to antiretroviral drugs, are now available for commercial use exclusively
from LabCorp facilities in the U. S.  These new testing systems are an
important advance in optimizing treatment choices in the fight against
HIV/AIDS.

"Testing resistance in the clinical setting empowers physicians and patients
to make rational decisions about drug therapy," said John Mellors, M.D.
director of the AIDS Program, University of Pittsburgh Medical Center.
"Knowing which medications are most likely to be effective against the HIV
virus prior to treatment permits us to make better informed choices."

Data shows a promising indication of the testing systems' ability to predict
response to therapy.  In outcomes studies using the Antivirogram-Trademark- 
and VircoGEN-Trademark-, physicians were able to predict antiviral response
in antiretroviral experienced patients.  One study done in collaboration with
the British Columbia Centre for Excellence in HIV/AIDS of 84 patients with
extensive prior nucleoside experience, found that patients with "sensitive"
virus, as indicated by phenotypic testing, (sensitivity being defined as the
ability of drugs to inhibit the virus) were twelve times more likely to
respond to ritonavir/saquinavir therapy.

-more-
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Patients whose virus was classified "sensitive" by genotypic testing, were
four times more likely to respond to the therapy.  The study included protease
inhibitor (PI)-experienced patients that were switching to the PI combination
ritonavir/saquinivir alone or in combination with other antiretroviral therapy
as salvage therapy.  Phenotyping and genotyping were conducted on isolates
from these patients using the Antivirogram-Trademark- and VircoGEN-Trademark-.

"Since the partnership between VIRCO and LabCorp was announced, our team of
scientists have been working diligently to bring the Antivirogram-Trademark-
and VircoGEN-Trademark- to market," said Dr. Myla Lai-Goldman, Executive Vice
President, Chief Scientific Officer and Medical Director of LabCorp.  "The
data validates the clinical importance of these systems and we are committed
to continuing our ongoing work to assess their broad capabilities."

To further substantiate the value of these testing procedures, a large study
of 1500 isolates collected from the patients provided an impressive data set
to correlate genotypic resistance patterns with phenotypic resistance
profiles.  While genotyping examines the drug resistance mutations accumulated
by the virus and may give an important indication of the possible evolution of
resistance, phenotyping measures virus growth in the presence of a drug.  When
used together, physicians can now assess how each patient is going to respond
to given therapy, thus allowing physicians to make more informed decisions
when selecting potent therapeutic regimens.

Turnaround time for the VicoGEN-Trademark- is five to 10 working days and
three to four weeks for the Antovirogram-Trademark-. LabCorp customer service
is available to provide additional information by calling 800-533-0567.

ABOUT THE COMPANIES
-------------------
Laboratory Corporation of America-Registered Trademark- Holdings (LabCorp-
Registered Trademark-) is a national clinical laboratory organization with
revenues of $1.5 billion in 1997.  The Company operates primary testing
facilities nationally, offering more than 1,700 different clinical assays,
from routine blood analyses to more sophisticated technologies.  LabCorp
performs diagnostic tests and procedures for physicians, managed-care
organizations, hospitals, clinics, long-term facilities, industrial companies,
and other clinical laboratories.

VIRCO is a privately-held high tech/molecular biology company that was founded
in 1995 by Rudi Pauwels, Ph.D. and Paul Stoffels, M.D. in Belgium, and Brendan
Larder, Ph.D. in the U.K.  VIRCO specializes in genomics and bioinformatics
applied to disease management and is at the forefront of the development and
implementation of complex technologies to monitor HIV drug sensitivity in
infected persons.  VIRCO's scientists have extensive experience in the field
of antiviral development and drug resistance, having performed phenotypic
resistance testing on more than 8,000 samples.

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