Curing AIDS: OHSU doc's HIV vaccine knocks out virus

Oregon doctor's possible cure for AIDS: How does it work?

His vaccine started as a fluke.

Dr. Louis Picker needed a bug to validate a breakthrough immunology test he developed that tracked the response of the body's fighting forces, T cells, to invaders like HIV.

He decided to use cytomegalovirus, a virus that infects up to 80 percent of Americans. The virus sticks around for life but rarely causes symptoms.

The test revealed that cytomegalovirus provoked a surprisingly powerful response from T cells, keeping them armed and on the front lines. No other virus that was largely benign fired up such a strong defense.

He figured that attribute would make it a good candidate for a vaccine against HIV, another virus he worked with at the University of Texas Southwestern Medical Center pathology lab in Dallas in the 1990s.

In 2000, Picker took a job at Oregon Health & Science University to develop his vaccine. Since then he has shown it can eradicate the virus from the body.

Dr. Louis Picker, HIV researcher

The immune system is not naturally trained to fight HIV. But it does stay armed against cytomegalovirus after exposure. So Picker decided to combine the two viruses. Using genetic engineering, HIV genes were inserted into the genome of the cytomegalovirus, creating a vaccine trained the immune system to be ready to attack an HIV-infected cell.

There are various types of T cells. Some sit in the barracks, waiting to be armed and trained for battle. It takes time to get them up to speed. Picker's vaccine marshals killer T cells, the body's shock troops. They can hit HIV fast and hard which is necessary because the virus is a master escape artist. Give it an edge and it will mutate faster than the body can adapt.

But his approach depends on HIV gaining a toehold, something that shocked other researchers when he proposed it. They were trying to develop vaccines that prevented infection in the first place by relying on antibodies, which cloak pathogens so they can't invade cells. Once they do, they turn them into viral factories.

"Louis is really swimming against the entire stream," said Klaus Fruh, senior scientist at OHSU.

Much to the surprise of the field, Picker's vaccine has eradicated the virus in more than 50 percent of the monkeys that have been infected.

Picker says the vaccine might be even more effective in people because he's been testing it against the monkey version of the virus, which is more virulent than HIV.

He just needs to put it to the test.

He'll do that for the first time next year in a clinical trial focused on safety. It will involve about 50 Portland-area men who are HIV negative but infected with cytomegalovirus. The volunteers will be divided into groups, with the first set getting the lowest dose. They'll be monitored for side effects. If everything's fine, the dose will be increased for the next set of volunteers. If they, too, don't experience adverse effects, the cycle will be repeated with a higher dose. And if still there are no side effects, a final group will get an even higher dose.

Picker expects the trial to take two years to complete.

-- Lynne Terry