Human Vaccine Testing: Not Ready for Prime Time
One of the most difficult challenges of the AIDS epidemic has been the search for a vaccine against HIV infection. One group became so frustrated that last week they offered themselves as human guinea pigs for vaccine testing. As a media event it was great theatre, but as a practical matter, no vaccine project is actually at the point of beginning human trials. A couple of projects, however, are poised for human safety testing to see if their vaccine is toxic to people.
Traditional vaccine techniques have exposed a person to a germ, generally dead or weakened, so that the immune system can devise a defense — chemical soldier proteins called antibodies — against the germ. The immune system then “remembers” what the germ was like, and if the real thing is ever encountered, the arsenal is already primed to fight.
A research group from Harvard Medical School has been quite successful with monkeys and SIV, the monkey equivalent of HIV. Their traditional technique, if applied to a crippled but complete HIV, carries some risk of infection, although the risk is believed to be minimal.
A University of Pennsylvania Medical Center research team may have made a major breakthrough in using an unusual vaccine technique in chimpanzee study subjects, as recently announced in the journal Natural Medicine. The chimp results have been so promising that they have launched a preliminary human safety trial.
Working with the biotech firm Apollon, the Penn group has used just genes from an HIV instead of an actual virus. The genes enter the chimpanzee’s cells and cause the cells to make the germ. The immune system then makes antibodies to kill those germs, while killer t-cells eliminate the infected cells. This type of technology is already being tested with herpes and flu viruses with very positive early results.
Having received the HIV genes, the chimps were then exposed to massive quantities of actual HIV. Their immune systems reacted exactly as intended, and more than a year later the chimps still show no sign of infection. While this small animal trial is certainly not conclusive, it is one of the most successful innovations in HIV vaccine research yet.
Having effective vaccines certainly will be an important step for the developed world. But for poorer developing countries, which cannot afford the expense of current treatments, forestalling infection with a vaccine is the only way to curtail this speeding epidemic.
— Sandy Bartlett, Information/Education Coordinator
AIDS Services of Austin
ASA Info Line: 458-AIDS
This article appears in October 3 • 1997 and October 3 • 1997 (Cover).