ViroLogic announces launch of ‘viral fitness’ assay for HIV infection

ViroLogic Inc has announced the launch of the first-ever commercial laboratory test to evaluate the “replication capacity” (often referred to as “viral fitness”) of HIV.

ViroLogic’s new Replication Capacity (RC) assay measures the ability of an individual’s HIV to make copies of itself and is designed to provide useful additional information to physicians to select optimal antiretroviral therapy cocktails for their patients.

The RC test will be provided in combination with ViroLogic’s PhenoSense HIV and PhenoSense GTT drug resistance tests, “at no additional charge,” according to the company.

“Successfully treating HIV has become increasingly complex, and having more information about the patient’s individual virus may help in making better treatment decisions,” said Charles Hicks, MD, Associate Clinical Professor of Medicine, Duke University Medical Center. “As HIV drug resistance and treatment failures continue to rise, the role of the replication capacity assay in clinical decision-making may prove to be of considerable value by providing supplemental individualized patient information.”

Replication capacity is a central component of viral fitness – the ability of a patient’s virus to survive and spread in the body. When a patient is on antiretroviral therapy, HIV often mutates to become resistant to the drugs in the treatment regimen. Although these mutations decrease the efficacy of the drugs, they can also impair the virus’ replication capacity, and limit the impact of HIV in the body.

ViroLogic’s proprietary technology provides a quantitative measure of replication capacity by comparing the ability of a patient’s virus to replicate with that of a wild-type reference virus. The test result is expressed a single percentage value. The replication capacity of wild-type virus is set at 100%, while patient results range from 0% (the virus is unable to replicate) to well over 100% (the virus can replicate more effectively than wild-type HIV).

Recent research studies suggest that replication capacity data, in combination with drug resistance information, viral load and CD4 count, may help physicians make a more informed prediction of HIV disease progression.

For example, using ViroLogic’s RC assay, physicians can identify situations in which the replication capacity of a patient’s virus is impaired because of resistance caused by exposure to antiretroviral drugs. In these cases, even though the antiretroviral drugs are no longer fully controlling replication of the virus, a physician may choose to maintain the regimen in order to keep the mutated, less “fit” strain of HIV in the patient’s body, especially if the patient has few or no other treatment options.