The Vectors Consortium

Some of the most effective anti-viral vaccines developed over the past century have been made from live but attenuated versions of the viruses they target—versions, in other words, that are highly unlikely to cause disease. But, for reasons having to do with safety, AIDS vaccines cannot be made this way. Indeed, most of the AIDS vaccine candidates under development today are constructed by inserting genes encoding HIV antigens into a unrelated and modified virus—or vector—often one that does not typically cause disease in humans. As an added measure of safety, such vectors are often rendered incapable of multiplying.

Viral vectors: Such vaccines consist of a weakened virus that is unrelated to HIV, into which HIV gene(s) have been inserted. The virus delivers HIV gene(s) to human cells.

In IAVI’s view, too little research has been done to broaden the capabilities of such vehicles of vaccine delivery. The Vectors Consortium (VEC), which started up in 2006, seeks to develop safe vectors that retain the ability to replicate in the human body. Researchers suspect that such vectors may be more likely to stimulate an effective immune response. We are particularly interested in developing replicating vectors likely to colonize the tissues of the gut, where HIV usually establishes a beachhead in the earliest stages of infection. A vaccine that trains specialized immune cells at these sites to recognize HIV could foil the virus in the earliest phases of its invasion.

Though still a young consortium, the VEC has made progress on several fronts. It has, in particular:

• Established a comprehensive program to design and systematically evaluate novel replicating vaccine vectors
• Is in the process of designing and constructing vectors derived from a number of viruses, most of which do not infect humans
• Developing and evaluating several adjuvants—materials often added to vaccines that are crucial to supporting a strong immune response
• Negotiated several agreements with companies for access to vectors, know-how and delivery devices to expedite the development of novel AIDS vaccine candidates

The VEC links leading academic labs to IAVI’s product development expertise to move novel vaccine concepts into development as swiftly as possible. Prototype vaccines will be assessed within the framework of a rigorous prioritization system that balances the potential efficacy and safety of each candidate with those of every other. Those that pass muster will be funneled into clinical trials conducted by IAVI’s global network of collaborating research centers.