Research team moves toward clinical trials of HIV vaccine

Although it could be more than a decade before it can be used in clinical practice, researchers at Oregon Health & Science University’s (OHSU) Vaccine and Gene Therapy Institute have developed a vaccine that may be able to reprogram immune cells to combat early HIV infection.

The vaccine is based on cytomegalovirus, which has been engineered to carry a protein that mimics one found in the HIV virus. Cytomegalovirus is a common virus that is often asymptomatic in those it infects, but keeps the immune system on “high alert,” according to Marcel Curlin, MD, an infectious disease specialist at OHSU who has been working on the vaccine.

By using a weakened version of the cytomegalovirus programmed with bits of HIV-like genetic material, the research team has been able to initiate never-before-seen immune reactions that train killer T-cells to identify cells infected with HIV.

Unlike other HIV studies currently in progress that use antibodies to attack the HIV virus, Curlin said this vaccine reprograms the immune system at the cellular level.

”It’s not really creating antibodies, rather it’s training cells to recognize infected cells,” Curlin told Medical Economics.

The reaction of the immune system to the engineered virus has been very surprising, and could be applied to other infections, as well, like tuberculosis, malaria, or cancer, he said.

“It sorts of violates the normal rules of immunology and creates immune responses that are completely unconventional,” Curlin said. “For whatever reason, it’s taking the classic pathway in all immunology and switching it all around.”

In animal studies, the research team has been able to clear 50% to 60% of early Simian immunodeficiency virus (SIV) infection in primates. The team hopes efficacy could increase in humans, since SIV is more potent than HIV.

The team is already moving toward Phase I clinical trials for the vaccine, which Curlin said could begin next year. During Phase I, individuals not infected with HIV will be given the vaccine to test its effects in a healthy body. Studies will initially focus on individuals not already infected with cytomegalovirus, then move on to those who already carry the virus who have natural immunity.

In later trials, the team hopes to test the vaccine in high-risk populations to see if infections rates decrease.

“It will really be the first time this kind of vector is tried in humans,” Curlin said.

Researchers are now recruiting for a safety study to learn more about individuals that already have cytomegalovirus, but no vaccine will be administered. Each phase of the trials will take several years, Curlin said, and the safety trial is expected to last three years alone.

Curlin said he hopes the trials will spur further research into whether the vaccine could be used to fight other diseases.