Although only tested for prevention in monkeys, the experimental drug protected the animals from infection in two studies reported at an AIDS conference on Tuesday.
"This is the most exciting innovation in the field of HIV prevention that I've heard recently," said Robert Grant, an AIDS expert at the Gladstone Institutes, a foundation affiliated with the University of California, San Francisco.
"Both groups are showing 100 percent protection" with the drug, Grant said of the two groups of researchers. "If it works and proves to be safe, it would allow for HIV to be prevented with periodic injections, perhaps every three months."
The two studies indicate shots may be a practical alternative:
- A study by the Centers for Disease Control and Prevention tested the shots on 12 monkeys. Six received shots of the drug and six others received dummy shots. All were exposed to the virus twice a week for 11 weeks, but only those that got the dummy shots were infected. The results mirror a CDC study on Truvada, a daily pill currently used to prevent HIV.
- A study by Chasity Andrews and others at Aaron Diamond AIDS Research Center at Rockefeller University in New York gave eight monkeys two shots of the drug, four weeks apart, and dummy shots to eight others. The animals were exposed to the virus weekly for eight weeks. Again, all animals given the fake treatment were quickly infected and those on the drug were all protected. To see how long a single shot would last, they did a second study. The single shot protected 12 monkeys for about 10 weeks on average.
"This is really promising," said Judith Currier, an infectious disease specialist at the University of California, Los Angeles. The research "supports moving this forward" into human testing, she said.
A mid-stage trial testing the long-acting shots in people as a treatment, not a prevention, is already underway, Grant said.
The Associated Press contributed to this report