GVI's Adjuvanted HIV Vaccine Program
Human immunodeficiency virus (HIV) is the most challenging vaccine target of our lifetime. All traditional approaches have been unsuccessful so far, as have many innovative new approaches. Recently, a Phase III trial combining two approaches, which had failed in individual trials, gave some indication of success. This involved a first inoculation with a poxvirus vaccine that had been engineered to express HIV proteins, and a second inoculation with a purified HIV protein. If the results are analyzed in the most favorable light, protection against infection reached statistical significance in about 30% of the subjects, but the protection lasted only 3-6 months. Nevertheless, decades after discovery of HIV, and the investment of untold time, money and research careers, even this modest indication that a protective vaccine might be possible was a very welcome result.
We feel that the GVI adjuvant could contribute significantly to improvement of this vaccination strategy. The capacity of the adjuvant to enhance antibody induction would be supplemented by its ability to induce cellular and mucosal immunity. Given that most HIV transmission globally is by heterosexual contact, the mucosal immunity aspect of the adjuvant may be of critical importance.
Live attenuated vaccines historically have been the most effective intervention in the fight to prevent infectious diseases. Such vaccines have eliminated smallpox from the entire globe and polio from the western hemisphere. In addition to their efficacy, live attenuated vaccines are relatively inexpensive to produce. However, there is an extremely low but finite risk with all of these vaccines that they can revert to being virulent (disease-causing) again.
In the case of HIV, we have licensed a technology that allows directed molecular construction of live attenuated virus vaccines using a genetic component from one virus and the antigenic elements from the virus targeted by the vaccine. These chimeric vaccines are predicted to be safe, very unlikely to revert, and highly efficacious. Additionally, the chimeric vaccine approach should be applicable to other diseases, such as hepatitis C, where chronic infection by the virulent virus would preclude development of a live attenuated vaccine.
More information on our HIV chimeric virus vaccine program can be found here.
This program has been supported by the International AIDS Vaccine Initiative (IAVI) and through IAVI, the Bill & Melinda Gates Foundation’s Collaboration for AIDS Vaccine Discovery (CAVD).