Genetically Engineered Version Of Virus Can Be Used To Treat People, May Result In Vaccine
Maryland-based Virxsys Corp said tests on monkeys showed its HIV-based vaccine might at least treat infections, if not prevent them, and it is now seeking permission to try it in people. And the privately held company is encouraged by some early results of a gene therapy approach to controlling HIV infection in people.
Neither result, presented to the Conference on Retroviruses and Opportunistic Infections in San Francisco, suggests any immediate change in treating the fatal and incurable virus.
But AIDS research has reached a plateau, with little progress toward making a vaccine that can prevent infection and drugs providing new ways to control the virus coming on the market, but nothing remotely close to a cure.
“I think the vaccine is all the more interesting because it is far more doable in the end,” said Joep Lange, who heads the Amsterdam Institute for Global Health and Development and who is a member of the company’s medical advisory board.
“It doesn’t prevent infection, but it does give good reduction in viral load,” Lange, a former president of the International AIDS Society, said in an interview.
The vaccine, called VRX1023, was tested in 15 monkeys at three different doses, said Gary Mc-Garrity, who heads science at Virxsys. The vaccine is made using a crippled AIDS virus – an approach that has been rejected as unworkable in the past.
While it did not protect the monkeys from infection, it did reduce how much virus circulated in the blood after they were infected, a measure called viral load. In humans, the lower the viral load, usually the healthier the patient is.
McGarrity believes it may work as a so-called therapeutic vaccine – one used to treat people who are already infected, as opposed to one that can prevent infection.
The second product is a gene therapy treatment called VRX496 that involves taking out a patient’s immune cells called CD4 T-cells — which are the cells that HIV infects.
These were treated with an RNA antisense product. RNA is the genetic material used by retroviruses such as HIV and antisense approaches use a type of mirror image of the genetic sequence to block genetic activity. A crippled HIV virus genetically engineered with the antisense sequence is used to infect these T-cells. REUTERS