New version of HIV vaccine could soon be ready for clinical trials

A promising vaccine that clears an HIV-like virus from monkeys is closer to human testing after a new, weakened version has been shown to provide similar protection to its original version.

Two recently-published papers have described how the vaccine – which uses a form of the common herpes virus cytomegalovirus (CMV) – was live-attenuated so CMV couldn’t spread as easily. The new version still managed to eliminate SIV, the monkey version of HIV, in 59 percent of vaccinated rhesus macaques.

That result is similar to earlier findings involving the vaccine’s original, non-attenuated version. The immunity generated by the attenuated vaccine was also long-lasting, as nine of 12 vaccinated monkeys could still fight off SIV infection three years later.

“This research, using rhesus CMV, provides potentially important insights into the design of a human CMV-based HIV vaccine,” said Dr Klaus Früh, a corresponding author on one of the papers. “We significantly attenuated CMV and still got the same type of immune responses as with the wild version of this vaccine.”

“These papers are important because they recapitulate the previously reported unique CMV vector efficacy with a genetically modified vector that is highly attenuated and therefore potentially safer for clinical use,” added Louis Picker, a corresponding author on both papers. “In addition, this new work demonstrates most vaccinated rhesus macaques that are protected against SIV can also be protected against a second challenge years after initial vaccination. This is a level of durability that would be very important for a human HIV vaccine”.

Picker and Früh are professors at Oregon Health & Science University’s Vaccine and Gene Therapy Institute and affiliated faculty in the OHSU School of Medicine’s department for molecular microbiology and immunology.

The CMV vaccine platform has been licensed by Vir Biotechnology Inc which plans to lead a clinical trial with a human version of the CMV-based HIV vaccine. The same platform is also expected to be used for vaccines being developed to fight tuberculosis.

The papers were published in Science Translational Medicine.