Scientists have developed a vaginal ring embedded with an antiviral drug that could potentially protect women against the virus that causes AIDS.
The plastic cervical ring contains MIV-150, a compound developed and being tested by scientists at the non-profit Population Council.
In experiments with macaques, only two of 17 female monkeys fitted ahead of time with the flexible ring became infected after being exposed to SHIV. That virus combines the genetic material of human immunodeficiency virus, or HIV, and a monkey version called SIV. At the same time, 11 of the 16 macaques with vaginal rings that did not contain any active drug became SHIV positive when exposed to the genetically engineered virus.
The results represent an 83 percent protection against the sexually-transmitted infection.
Melissa Robbiani, director of biomedical HIV research at the Population Council, said the microbicide-containing cervical ring would be simple to use and has advantages over short-term protection methods, such as gels or creams that are placed into the vagina or rectum before sexual intercourse.
“It is not dependent upon someone applying it just before intercourse and, on a daily basis, it would be in there hopefully for a month, two months, three months. That’s hopefully going to help the advantage,” said Robbiani.
The ring is similar to a contraceptive ring that’s currently on the market. Once inserted, it is held in place by muscles in the vaginal canal. The MIV-150 compound, Robbiani believes, acts as a shield in the mucosal tissue at the cellular level, where HIV gains entry into the body.
She said the difference between the drug-infused ring and a topical microbicide may be that the drug delivery device offers continuous protection against the virus with MIV-150, while other microbicides wear off quickly. Testing the monkeys two weeks after exposure to SHIV, researchers found the ring provided significant protection whether it had been inserted two weeks or just 24 hours earlier.
Future experiments will look at how long a ring containing MIV-150 must remain inserted to be fully effective. Researchers also are trying to develop a ring that can be left in place for three months. Robbiani said scientists also are focusing on the drug's formula.
“The next stage would actually be incorporating other antiviral components that would make it even more potent and broader acting. And that would actually be a further strength of this ring,” said Robbiani.
Researchers at the New York-based Population Council describe their work with a vaginal ring to protect against HIV infection in the journal Science Translational Medicine.