"Our results show this new vaccine is capable of inducing the kind of powerful immune response that we and others believe will be critical for controlling HIV infection," says Hildegund C.J. Ertl, M.D., professor and immunology program leader at The Wistar Institute, and senior author on the new study.
Given the history of HIV, Ertl emphasize the lengths to which she and her colleagues have gone to ensure that the new vaccine is completely safe. To eliminate the possibility of any contaminant - an HIV-like stowaway, for example - the vaccine is derived in the laboratory from a set of genetic instructions. Importantly, too, the genes that would be needed by the viral vaccine to replicate are deleted from those instructions.
The vaccine is based on a chimpanzee adenovirus. In chimpanzees and humans, adenoviruses are a common cause of respiratory-tract infections. Immunologists have understood for some time that human adenoviruses can be retooled in the laboratory to serve as the basis for vaccines against an array of viral diseases. They easily enter human cells and stimulate a vigorous, long-lasting immune response. A number of vaccines based on human adenoviruses, including some against HIV, are now in development.
An unaddressed concern with these vaccines, however, is the question of pre-existing immunity. Adenoviruses are nearly ubiquitous among humans, so much so that more than 45 percent of the population has neutralizing antibodies circulating in the blood able to impair any vaccine based on a common human adenovirus. But the new chimpanzee adenovirus vaccine possesses the immunological
Contact: Franklin Hoke
The Wistar Institute