ViroLogic's Entry Assay May Accelerate HIV Vaccine Development According to Study

SOUTH SAN FRANCISCO -- ViroLogic, Inc. today announced that results of a study published in this week's issue of the Proceedings of the National Academy of Sciences (PNAS) suggest that its novel, proprietary PhenoSense HIV Entry assay could significantly accelerate the development of HIV vaccines.

"The study's key finding, which is that antibodies generated in response to HIV infection play a more crucial role in the body's effort to fight the virus than previously recognized, is one of the most important scientific discoveries made to date using our technology," said Dr. Christos Petropoulos, vice president of research and development at ViroLogic and co-author of the study. "Before the introduction of our PhenoSense HIV Entry assay for vaccines, it would have taken years to generate the data for this study using conventional assays. We believe ViroLogic's rapid entry assay will play a significant role in vaccine development as researchers and developers seek to capitalize on the implications of this study."

The study revealed that antibodies actively work to suppress HIV following infection, failing only when the virus mutates into antibody-resistant forms. As new antibodies are produced to fight the mutated virus, HIV continues to mutate to again evade the new antibodies. The result is a constantly evolving population of HIV and anti-HIV antibodies in which the virus inevitably outpaces the antibodies, until the virus eventually depletes the body's immune response (or virus fighting cells). These findings suggest that HIV-specific antibodies play a much greater role in virus suppression than previously appreciated.

This appreciation for the role of antibodies may have important implications for HIV vaccine research, which in recent years has focused on vaccine candidates that stimulate the body's cellular immune response to defend itself against infection. The study raises the prospect that a vaccine that stimulates an antibody response to a broad range of HIV variants may be a useful component of an effective vaccine strategy.

"These data suggest that if we can develop a vaccine that stimulates a wide range of antibody responses prior to HIV exposure, the body may be better able to defend itself from infection," said Dr. Douglas Richman of the VA San Diego Healthcare System and head of the research team. "I'm hopeful that these findings and the widespread availability of this innovative entry assay will help move AIDS vaccine development forward more quickly by facilitating clinical evaluation of vaccine candidates."

According to the AIDS Vaccine Advocacy Coalition, nearly a dozen biopharmaceutical companies are currently engaged in HIV vaccine research, as well as the National Institutes of Health, the Department of Defense and numerous academic research centers.

The study published in PNAS examined plasma samples from 14 recently infected patients. Antibodies and HIV were extracted from samples taken at 2-4 month intervals over an average of 18 months and analyzed using the entry assay, which measured the ability of each patient's antibodies to suppress the virus. By examining the evolution of each patient's virus and antibody response to their own virus over time, the researchers were able to identify clear patterns suggesting a significant selective pressure of antibodies on the virus.

ViroLogic is a biotechnology company advancing individualized medicine by discovering, developing and marketing innovative products to guide and improve treatment of serious viral diseases such as AIDS and hepatitis. The company's products are designed to help doctors optimize treatment regimens that lead to better patient outcomes and reduced costs. ViroLogic's technology is also being used by numerous biopharmaceutical companies to develop new and improved antiviral therapeutics and vaccines targeted at emerging drug-resistant viruses.

Source: ViroLogic, Inc.