Friday, February 25, 2005

By Daniel J. DeNoon

A vaginal gel has strong HIV- and herpes-blocking action even an hour after use.

The gel is PRO 2000, now in large-scale clinical tests. It's hoped that the
odorless, colorless product  what scientists call a vaginal microbicide  will
slow
the spread of HIV and other sexually transmitted diseases.

The new findings come in a report by Mount Sinai School of Medicine researcher
Marla Keller, MD, at this week's 12th Conference on Retroviruses and
Opportunistic Infections in Boston.

"There is an urgent need for the development of safe and effective vaginal
microbicides," Keller says, in a news release. "While condoms offer protection
against sexually transmitted infections, their effectiveness is limited because
they require partner initiation or consent."

A vaginal microbicide thus offers women a way to protect themselves against HIV
and STDs, even if their sex partner refuses to use a condom.

Keller's team randomly gave PRO 2000  or an identical gel with no active
ingredient  to 20 women with HIV infection. An hour later, they collected
vaginal
fluids from each of the women. In lab studies, they tested whether these vaginal
fluids could prevent HIV or herpes infection of human cells.

PRO 2000 treatment made it nearly 1,300 times harder for HIV to infect cells 
nearly 500 times better than placebo. PRO 2000 also made it 2,600 times
harder for herpes simplex virus (search) to infect cells  about 260 times
better than placebo.

And there's more good news: A microbicide won't do much good if it causes
inflammatory responses that make vaginal tissues redden and swell. Analysis of
PRO 2000-treated fluids showed no sign of the chemical messengers that trigger
these unwanted responses.

The U.S. National Institute of Allergy and Infectious Diseases recently
announced the start of a large trial testing PRO 2000 and another vaginal
microbicide,
BufferGel. Unlike PRO 2000, which contains a virus-blocking agent, BufferGel
boosts the vagina's natural acidity, which hinders the ability of the virus to
infect cells. The 2.5-year trial will take place in Philadelphia, South Africa,
Malawi, Tanzania, Zimbabwe, and Zambia.

PRO 2000 is made by Indevus Pharmaceuticals, in Lexington, Mass. BufferGel is
made by ReProtect Inc., in Baltimore, Md.

By Daniel J. DeNoon, reviewed by Michael W. Smith, MD

SOURCES: Keller, M. 12th Conference on Retroviruses and Opportunistic
Infections, Boston, Feb. 22-25; abstract 535. News release, Mount Sinai School
of
Medicine, Feb. 24, 2005. News release, NIAID, Feb. 11, 2005.