Study confirms VirtualPhenotype™ can predict response to HIV therapy from genetic resistance information

September 19, 2000

Test may fulfill need for standardized interpretation

TORONTO, ONTARIO, September 20, 2000 - Results presented today at the 40th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) indicate that the VirtualPhenotype™, Virco's new automated HIV drug resistance test, can predict response to therapy from genetic information with comparable results to a panel of international experts.

"This study confirms that genotypic resistance information with sophisticated interpretation, such as that provided by the Virtual Phenotype or our panel of expert clinicians, is a useful predictor of response to therapy and significantly better than relying on the treatment history, which can be misleading," commented lead investigator Dr. Victoria Johnson of the University of Alabama, Birmingham, in collaboration with the University of Alabama HIV database program under the direction of Dr. Michael Saag. "This adds to the growing weight of evidence supporting the clinical utility of resistance testing."

In the study, the use of interpreted genotypic resistance information was highly predictive of the patient's response to therapy. This contrasted with use of the treatment history of each patient (the information on which treatment decisions have been made prior to the development of HIV drug resistance testing), which was found not to be predictive of treatment response.

The study compared the "proportional hazard" of virologic failure if the expert or VirtualPhenotype™ predicted susceptibility to the drug in question. The results for each of the experts, for all combined and for VirtualPhenotype™ were 0.71, 0.70, 0.75, 0.65, 0.67 and 0.69 respectively. All except Expert 3 were significantly predictive of outcome (p<0.05).

The study also revealed differences between the interpretation of different experts, highlighting the need for standardization of genotypic interpretation to ensure optimal treatment decision-making.

"Given the complexity of HIV drug resistance, only a relatively small number of experts can undertake interpretation of genotypic information with real confidence and the virtual phenotype represents a viable and reliable alternative for standardized interpretation of genotypic information," adds Dr. Johnson.

HIV genotyping involves reading the genetic code to detect where mutations have occurred that could confer resistance to one or more of the 15 HIV drugs currently available. The chief limitation of this approach is that there are over 100 mutations that can interact and counteract one another in highly complex ways to cause resistance. This makes the interpretation of raw genotypic resistance information extremely difficult, which underscores the need for standardization of the interpretation.

Historically, the only alternative to genotyping has been phenotyping where the virus is derived from the patient's blood sample and grown in the presence of varying concentration of all the available drugs in the laboratory. This is more complex to perform and requires more time than genotyping.

Virco's solution to this is a new, third approach to HIV drug resistance monitoring - the VirtualPhenotype™. First the genetic code is read and all the resistance mutations detected. These data are then entered into Virco's computerized system that searches the World's largest database of approximately 100,000 genotypes and phenotypes for samples with the same patterns of mutations. Once these are found, the system retrieves the corresponding phenotypes for these samples (typically thousands per drug) and calculates the average resistance score for each drug. The VirtualPhenotype™ provides the highest quality of interpretation with a quantitative estimate of resistance to each drug available to all physicians.

Data presented earlier this year demonstrated that the VirtualPhenotype™ is highly predictive of actual phenotypic drug resistance and of treatment response, and superior to other current interpretation systems that interrogate simplified resistance tables or 'rules' to predict resistance.
-end-
Virco is a multinational biotechnology company with facilities in the United States, the United Kingdom, Belgium and Ireland. It applies the most advanced technologies in molecular biology, automation, ultra high-throughput screening and electronic data processing to the diagnosis and management of HIV, other infectious diseases and cancer. Virco is the only company to provide genotyping, phenotyping and the new, unique VirtualPhenotype™for testing HIV drug resistance. The company believes it provides the most sophisticated and comprehensive portfolio of HIV drug resistance monitoring and decision support tools for physicians treating HIV infected patients.

Virco sells its testing services via Laboratory Corporation of America Holdings (LabCorp), SRL in Japan, as well as directly to HIV/AIDS centres in Europe, Canada, Australia and other countries around the world. Virco has a two-year agreement with Gilead Sciences for the promotion of Virco Resistance Monitoring Services to US HIV prescribers by the Gilead sales force. For further information, please visit Virco's website: http://www.vircolab.com.




Cooney Waters Group, Inc.

Related Genetic Information Articles from Brightsurf:

Genetic information can predict predisposition to rare and common blood diseases
Two large-scale genetic studies have identified the bulk of genetic variation that influences medically-important characteristics of our blood cells.

Biomedical research may miss key information by ignoring genetic ancestry
A new study of Black residents of four distinct US cities reveals variations in genetic ancestry and social status that underscore the inadequacy of using skin color as a proxy for race in research.

Combining genetic information with EMRs to pinpoint childhood epilepsies
A team of researchers further bridged the gap between genomic information and clinical outcome data by systematically linking genetic information with electronic medical records, focusing on how genetic neurological disorders in children develop over time.

New imaging method gives insights into how bacteria move and exchange genetic information
Scientists have made a pivotal breakthrough in advancing our understanding of how bacteria move and perform genetic exchange -- that could potentially lead to the development of new antimicrobial drugs.

New tool helps gather useful genetic information obtained from blood, skin tissues
Hoping to refine the usefulness of RNA sequencing, a team of researchers reviewed a database of RNA sequencing results in non-clinically-accessible tissues from organs like the brain and heart.

Computational human cell reveals new insight on genetic information processing
Researchers have developed the first computational model of a human cell and simulated its behavior for 15 minutes -- the longest time achieved for a biological system of this complexity.

Calculating genetic links between diseases, without the genetic data
In a new study, data scientists from the University of Chicago estimated heritability and mapped out relationships among thousands of diseases using data from electronic health records.

Foraging for information: Machine learning decodes genetic influence over behavior
Mice scurry around while foraging for food, but genetics may be the unseen hand controlling these meandering movements.

Bringing information into the cell
Researchers at the Paul Scherrer Institute PSI have elucidated an important part of a signal pathway that transmits information through the cell membrane into the interior of a cell.

Researchers find new genetic information behind urogenital track anomalies
Researchers at the University of Helsinki have developed a new mouse model of congenital anomalies of kidney and urinary tract and disease progression.

Read More: Genetic Information News and Genetic Information Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.