RESEARCHERS TRACK HEPATITIS C, AIDS EPIDEMICS THROUGH CHINA

SEATTLE -- By genetically fingerprinting the AIDS and hepatitis C viruses,
researchers from China and New York have shown that the world's
most-populous nation is suffering from distinct epidemics of these
blood-borne microbes. Separately, another team of researchers showed just
how fast HIV mutates, finding that it evolves far more swiftly than the
influenza virus.

The Yunnan province in the southwest region of China abuts the Golden
Triangle, a major source of heroin . Here, the HIV and hepatitis C
epidemics are driven by injection drug users, who share infected needles.
In this region, a strain of HIV, called subtype C, extends north from
Yunnan along the old Silk Road, which is now used by drug couriers.
Similarly, the hepatitis C virus, called HCV, is dominated in this same
region by a strain called subtype 3.

But in the heartland of China, in the Henan province south of Beijing, the
epidemic has been spread largely by contaminated blood donations. Illegal
blood centers paid donors for blood, and some of these donors were infected
with HIV and HCV. Here, the HIV subtype is predominantly B, and the HCV
subtypes are largely 1 and 2.

Yunnan province is inhabited by some of China's ethnic minorities, and the
region is marked by low incomes and education, said Yunzhen Cao, a
researcher with China's National Center for AIDS Prevention and Control and
a visiting scientist at the Aaron Diamond AIDS Research Center in New York.
In the past, the Chinese government has thwarted prevention programs, such
as needle exchanges, known to slow the spread of HIV among drug users. But
Dr. Cao said the government has recently allowed some pilot needle-exchange
programs to start up, as well as AIDS education for commercial sex workers.
She also said the government has cracked down on illegal blood centers.

The study was presented here at the 9th Conference on Retroviruses and
Opportunistic Infections by Linqi Zhang of the Aaron Diamond Center, which
is laying the groundwork for possible trials of an AIDS vaccine and which
has helped start AIDS treatment trials in China, run by Dr. Cao.

In a separate study, Douglas Richman of the University of California
revealed the startling ability of HIV to mutate its outer envelope. That is
the part of HIV targeted by the immune system's antibodies, which snare
free-floating virus. "We see in six months in one patient what happens to
the influenza virus around the globe in a decade," said Dr. Richman.

That presents a challenge to vaccine makers, who hope to stimulate
antibodies that neutralize HIV by binding to its envelope. But Dr. Richman
saw hope in his study. The fact that HIV mutates rapidly means antibodies
are placing "incredibly strong selective pressure" on the virus, forcing it
to keep changing to elude the immune system's powerful antibodies. But,
said Dr. Richman, if a vaccine could induce such antibodies before the
virus got a foothold inside the body, then maybe they could repel an infection.